WO2015101666A1

WO2015101666A1 - VLPs, METHODS FOR THEIR OBTENTION AND APPLICATIONS THEREOF

Info

Publication number: WO2015101666A1
Application number: PCT/EP2015/050054
Authority: WO
Inventors: José Francisco Rodríguez Aguirre; Diego Marcelo GUÉRIN AGUILAR
Original assignee: Fundación Biofísica Bizkaia; Universidad Del País Vasco; Consejo Superior De Investigaciones Científicas
Priority date: 2014-01-03
Filing date: 2015-01-05
Publication date: 2015-07-09
Also published as: EP3089755A1

Abstract

The present invention belongs to the field of virus and virus-like particles (VLPs) as is related to VLPs derived from Triatoma virus(TrV) comprising a heterologous polypeptide, a process for obtaining a Triatoma virus VLP modified to express a heterologous protein of interest, polynucleotides comprising the necessary elements for generation of recombinant TrV virions and the process for obtention of said polynucleotides. The invention relates as well to a process for obtaining infectious TrV particles.

Description

VLPs, METHODS FOR THEIR OBTENTION AND APPLICATIONS

THEREOF

FIELD OF THE INVENTION

The present invention belongs to the field of virus and virus-like particles (VLPs) as it relates to VLPs derived from Triatoma virus (TrV) comprising a heterologous polypeptide, a process for obtaining a Triatoma virus VLP modified to express a heterologous protein of interest, polynucleotides comprising the necessary elements for generation of recombinant TrV virions and the process for obtention of said polynucleotides.

BACKGROUND OF THE INVENTION The use of vaccines based on attenuated or inactivated forms of the whole pathogens has been the traditional strategy for inducing human and animal immunization. Alternatively, subunits of pathogens such as proteins, sugars and peptides, has been also employed as vaccines, but due to their poor immunogenicity and in order to stimulate the immune response, vaccines based on small portion of an antigen have to be formulated with adjuvants. Unfortunately, current adjuvants cause toxicity and other side effects such as inflammation.

A more recent and promising method to produce vaccines is to introduce antigen epitopes in VLPs. Although this approach has some technical limitations, like the size and accessibility of the epitope, and unpredictable modifications of the native viral capsid, some remarkable achievements have shown the potency of this technology to the design and production of vaccines. It is also well established that VLPs are potent inducers of immune response for both themselves and also against any antigen displayed on them. The possibility of producing VLPs recombinantly, achieving high yield in a short time, and at low cost of goods, makes this technology for producing vaccines very promising.

Virus-like particles (VLPs) are structures built in an organized and geometrically regular manner from many polypeptide molecules of one or more types. Being comprised of more than one molecule, VLPs can be referred to as being supramolecular. VLPs lack the viral genome and, therefore, are noninfectious. VLPs can be produced in large quantities by heterologous expression and can be easily purified. The geometry of a VLP typically resembles the geometry of the source virus particle. VLPs are being exploited in the area of vaccine production because of their structural properties, their ease in large scale preparation and purification, and their non-infectious nature.

Examples of VLPs include the self-assemblages of capsid or nucleocapsid polypeptides of hepatitis B virus, Sindbis virus, hepatitis C virus, rotavirus, Norwalk virus, retroviruses, retrotransposons and human papilloma virus. Plant-infecting virus capsid polypeptides also self-assemble into VLPs in vitro and in vivo.

The structural components of some VLPs have also proven amenable to the insertion or fusion of foreign antigenic sequences, allowing the production of chimeric VLPs exposing the foreign antigen on their surface. Other VLPs have been used as carriers for foreign antigens, including non-protein antigens, via chemical conjugation.

Methods for generating VLPs linked to antigens through protein-protein interaction have been described in WO 2011057134 Al . Similarly, antigen presenting systems based on VLP particles have been described in the art. WO 1996030523 A2 describes an antigen presentation system based on retrovirus- like particles, WO 2011091279 A2 describes antigen presentation based on calicivirus VLPs, WO 2010118424 A2 describes a VLP based on papilloma virus LI major capsid protein comprising a neutralizing epitope of a papillomavirus L2 protein, WO 2011102900 Al describes VLPs that display one or more truncated, re-engineered or remodeled hemagglutinin molecules on their surface.

However, the insertion of epitopes into particular VLPs remains fairly unpredictable despite some remarkable successes. Major limitations include accessibility of the epitope, size limitations, and perturbation of the structure of the viral protein by the inserted epitope, and enforcement of a non-native structure on the epitope. In addition, some of the viral carriers face major challenges for regulatory approval due to infectivity or presence of DNA and resistance genes.

However, despite the efforts made to date, there still exists a continuing need in the art for novel ways of introducing antigen epitopes in VLPs compounds, as well as developing VLPs useful in eliciting an immune response against particular antigen epitopes.

SUMMARY OF THE INVENTION

The inventors have developed a system for heterologous antigen presentation based on VLPs derived from the insect viral pathogen Triatoma virus (TrV) (Dicistroviridae :Cripavirus, Dicistroviridae family, Cripavirus genus). This antigen presenting system, called TrV-VLP (or TRWLP), allows epitope exposure on the internal or external surface of the VLPs by insertion or substitution of amino acids, thus facilitating their recognition by the immune system and/or increasing their immunogenicity. Furthermore, production of TrV-VLPs bearing different epitopes may occur through the expression in insect cells by infection of recombinant baculoviruses.

In a first aspect, the present invention relates to a VLP comprising

(i) the viral structural proteins VPl, VP2, VP 3 and VP4 of a virus of the

Dicistroviridae family, or the viral structural proteins VPl , VP2, and VPO of a virus of the Dicistroviridae family, or the structural protein precursor (PI) from a virus of the Dicistroviridae family, or a functionally equivalent variant any thereof, and

(ii) a heterologous polypeptide,

wherein said heterologous polypeptide is provided as a fusion protein with at least one of said viral structural proteins.

In a second aspect, the present invention relates to a polynucleotide encoding a fusion protein selected from the group consisting of

(i) a fusion protein comprising a structural protein from a virus of the Dicistroviridae family selected from the group consisting of VPl, VP2, VP3, VP4 and VPO, or a functionally equivalent variant thereof, and a heterologous polypeptide, or

(ii) a fusion protein comprising a structural protein precursor (PI) from a virus of the Dicistroviridae family, or a functionally equivalent variant thereof, and a heterologous polypeptide.

In a further aspect, the invention relates to a vector comprising the polynucleotide encoding a fusion protein as above. In a further aspect, the invention relates to a host cell comprising the polynucleotide encoding a fusion protein or the vector as above.

In a further aspect, the present invention relates to a process for obtaining a Dicistroviridae family virus VLP modified to express a heterologous polypeptide of interest comprising the steps of:

(i) contacting a host cell with a first polynucleotide which encodes a fusion protein comprising a heterologous polypeptide of interest and the structural protein precursor (PI) of a virus of the Dicistroviridae family or a functionally equivalent variant thereof, and

(ii) maintaining the cells under conditions suitable for the expression of the polynucleotide introduced in the cell in step (i).

In a further aspect, the present invention relates to the VLP obtainable by the process above.

In a further aspect, the present invention relates to a vaccine or immunogenic composition comprising the VLP as above.

In a further aspect, the present invention relates to a VLP, to a polynucleotide, or to a vector as mentioned above for use in the treatment of an infectious disease caused by a pathogenic organism and/or an immune reaction caused by an allergen from which the heterologous peptide is derived.

In a further aspect, the present invention relates to a R A polynucleotide comprising in the 5 ' to 3 ' direction:

(i) a first autocatalytic ribozyme capable of cleaving the sequence containing said ribozyme at the 3 ' end of the ribozyme,

(ii) the 5 ' UTR of the TrV virus genome,

(iii) a sequence region encoding the non-structural protein precursor NS of the Triatoma virus or a functionally equivalent variant thereof,

(iv) the intergenic region of the genome of TrV virus,

(v) a sequence region encoding the structural protein precursor PI of the Triatoma virus or a functionally equivalent variant thereof,

(vi) the 3 ' UTR of the TrV virus genome and

(vii) a second autocatalytic ribozyme capable of cleaving the sequence containing said ribozyme at the 5' end of the ribozyme. In a further aspect, the invention relates to a DNA polynucleotide having at least one strand which is complementary to the R A polynucleotide as above, further comprising a transcriptional regulatory region which regulates the expression of said DNA polynucleotide

In a further aspect, the present invention relates to a process for obtaining an infectious Triatoma virus (TrV) comprising the steps of:

(i) contacting a host cell with a polynucleotide as mentioned under conditions suitable for the entry of said polynucleotide into the cell, and

In a further aspect, the invention relates to an infectious Triatoma virus (TrV) obtained by the process above.

In a further aspect, the invention relates to a method for killing insects comprising the administration of an infectious Triatoma virus (TrV) as above.

DESCRIPTION OF THE FIGURES

Figure 1. Negatively stained transmission electron micrograph of TrV VLPs obtained according to the invention (magnification 80,000x). The VLPs are of about 30 nm in diameter and were obtained by means of contacting the host cell with two polynucleotides. The first polynucleotide corresponds to the sequence encoding the TrV structural proteins (PI), and the second polynucleotide comprises the sequence encoding for the non- structural protein precursor of TrV (NS).

Figure 2. Negatively stained transmission electron micrograph of TrV VLPs obtained according to the invention (magnification 80,000x). The VLPs are of about 50 nm in diameter and were obtained by means of contacting the host cell with only one polynucleotide sequence encoding for the TrV structural protein precursor PI .

Figure 3. Immuno-stimulatory properties of TrV VLPs. Mouse spleen cells were immunized in vitro with TrV, empty TrV and recombinant TrV VLPs. The data showed that the recombinant VLP has good immunostimulatory properties. Figure 4. Accessibility of reactive groups on the TrV VLPs external surface. Fluorescein is conjugated to Lys residues exposed on the surface of the VLP.

DETAILED DESCRIPTION OF THE INVENTION

The authors of the present invention have developed VLPs based on the Triatoma virus (TrV), an insect virus of the Dicistroviridae family, wherein said VLPs comprise a heterologous polypeptide of interest, such as an epitope or a biotin acceptor peptide (BAP). Since TrV is an insect virus, the VLPs according to the present invention are adequate to be produced in high yield using insect cells in a baculo virus expression system. It is known that the TrV capsid resists very acidic conditions. Therefore, since a vaccine based on the VLPs according to the present invention is likely resist acidic environments, vaccines based on the TrV- VLP platform are considered to be suitable for oral administration.

Definitions

The term "5 '-end" designates the end of a nucleotide strand that has the fifth carbon in the sugar-ring of the deoxyribose at its terminus.

The term "3 '-end" designates the end of a nucleotide strand that has the hydroxyl group of the third carbon in the sugar-ring of the deoxyribose at its terminus.

The term "biotin acceptor peptide" or "BAP", as used herein, relates to a peptide with the capacity to bind to biotin or to an analog thereof (e.g. 2-iminobiotin, etc.). Illustrative, non- limiting, examples of BAP are mentioned in EP711303 (incorporated in its entirety in this description as a reference). Many biotinylated ligands are commercially available or can be prepared by standard methods. Processes for coupling a biomolecule, e. g. a protein molecule, to biotin are well known in the art (Bayer and Wilchek 1992 Methods in Mol Biol 10, 143).

The term "biotin-binding molecule", as used herein, relates to a member of a binding pair that binds to biotin. Particularly, the biotin-binding molecule is avidin, streptavidin (SA) or SA or avidin fragments which retain substantial binding activity for biotin, such as at least 50 percent or more of the binding affinity of native SA. As used herein, the term "avidin" refers to a glycoprotein found in egg whites and in tissues of birds, reptiles and amphibians protein and which has the capacity to bind to biotin with high affinity as well as any expressed or engineered form of the avidin biotin-binding molecule, such as streptavidin, neutravidin and the like. The term avidin includes both avidin found naturally in the eggs of Gallus gallus (NCBI accession numbers NM_205320.1 / GL45384353en, release as of 14 May 2013) as well as the orthologues of said protein in other species. Streptavidin, corresponding to the protein from Streptomyces avidinii (accession number CAA00084.1 in GenBank, release as of 28 January 1993), as well as the orthologues, homologues and fragments of streptavidin defined in the same manner as avidin. Streptavidin comprises 4 subunits each of which contains a binding site for biotin. Streptavidin (SA) or avidin fragments which retain substantial binding activity for biotin, such as at least 50 percent or more of the binding affinity of native SA or avidin, respectively, may also be used. Preferably, the affinity of the avidin variant for biotin is of at least 10¹⁵ M^"1, 10¹⁴ M^"1, 10¹³ M^"1, 10¹² M^"1, 10¹⁰ M^"1 or 10⁹ M^"1.

Avidin and estreptavidin variants suitable for use in the present invention include, without limitation:

"Core streptavidin" ("CSA"), which is a truncated version of the full-length streptavidin polypeptide which may include streptavidin residues 13-138, 14- 138, 13-139 and 14-139. See, e.g., Pahler et al, (J. Biol. Chem. 1987, 262: 13933-37).

Truncated forms of streptavidin and avidin that retain strong binding to biotin (See, e.g. Sano et al, (J Biol Chem., 1995, 270: 28204-09) (describing core streptavidin variants 16-133 and 14-138) (U.S. Pat. No. 6,022,951). Mutants of streptavidin and core forms of streptavidin which retain substantial biotin binding activity or increased biotin binding activity. See

Chilcoti et al, Proc Natl. Acad. Sci. USA. Feb. 28, 1995;92(5): 1754-8; Reznik et al, Nat Biotechnol. August 1996;14(8): 1007-1 1.

Mutants with reduced immunogenicity, such as mutants mutated by site- directed mutagenesis to remove potential T cell epitopes or lymphocyte epitopes,. See Meyer et al, Protein Sci. 2001 10: 491-503.

Mutants of avidin and core forms of avidin which retain substantial biotin binding activity or increased biotin binding activity also may be used. See Hiller et al, J. Biochem. (1991) 278: 573-85; Livnah et al. Proc. Natl. Acad. Sci. USA (90: 5076-80 (1993).

Variants resulting from the chemical modification of avidin such as those resulting from the complete or partial modification of glycosylation and fragments thereof as well as the completely deglycosylated avidin variant known as neutravidin.

- Avidin mutants as described in WO05047317A1

- Avidin- like proteins as described in WO06045891 ,

Recombinant avidin as described in WOO 198349,

- Avidin variants as described in WO0027814,

Monomeric streptavidin as described in WO06084388,

Modified streptavidin dimers such as those described in WO06058226, The protein with biotin binding capacity as described in WO04018509, Streptavidin having a higher affinity for biotin as described in WO9840396, - The modified streptavidin and avidin molecules as described in

WO9640761,

The streptavidin mutants as described in W09711183,

The streptavidin with modified affinity as described in WO9624606. For convenience, in the instant description, the terms "avidin" and "streptavidin" as used herein are intended to encompass biotin-binding fragments, mutants and core forms of these binding pair members. Different avidin variants are commercially available, such as Extravidin (Sigma-Aldrich), NeutrAvidin (Thermo Scientific), NeutrAvidin (Invitrogen) and NeutraLite (Belovo). Moreover, the nucleic acid sequences encoding streptavidin and avidin and the streptavidin and avidin amino acid sequences can be found, for example, in GenBank Accession Nos. X65082; X03591; NM --205320; X05343; Z21611; and Z21554.

The expression "capable of interacting specifically" or "specific interaction", as used herein in the context of the first and second members of a binding pair, describes the interaction between a first species and a second species characterized in that the nature of the binding is such that a an antibody, a receptor or a nucleic acid binding protein binds to its corresponding binding partner but does not substantially bind to other species. Likewise, as used herein, the term "binding" or "binding to" means the physical association between a first species and a second species, for example, the binding of a ligand by a receptor, the binding of an antigen by an antibody, the binding of a nucleic acid by a nucleic acid binding protein, etc.

The term "cleavage" or "cleavage activity", as used herein, relates to R A cleavage performed by a ribozyme in specific RNA sites. In a particular embodiment, the ribozyme is an autocatalytic ribozyme.

The term "Dicistroviridae family", as used herein, relates to a family of Group IV (positive sense single stranded RNA) arthropod-infecting viruses, particularly insect- infecting viruses. Some insects commonly infected by dicistro viruses include, without limitation, aphids, leafhoppers, flies, bees, ants, crickets, triatomines and silkworms. Viruses of this family are characterized by the location of their structural protein genes at the 3' end of the genome, and by having two genomic segments. The Dicistroviridae family includes Aparavirus and Cripavirus genuses. In a particular embodiment, the insect from the Dicistroviridae family is an insect from the Cripavirus genus, more particularly a Triatoma virus (TrV) or a Cricket paralysis virus (CrPV), preferably TrV.

The term "epitope" as used herein, refers to that portion of a given immunogenic substance that is the target of, i.e., is bound by, an antibody or cell-surface receptor of a host immune system that has mounted an immune response to the given immunogenic substance as determined by any method known in the art. Further, an epitope may be defined as a portion of an immunogenic substance that elicits a humoral or cellular, response, in particular an antibody response or a T-cell response in an animal, as determined by any method available in the art (see, for example, Geysen et al, Proc Natl Acad Sci (1984) Vol.81 3998-4002). An epitope can be a portion of any immunogenic substance, such as a protein, polynucleotide, polysaccharide, an organic or inorganic chemical, or any combination thereof. The term "epitope" may also be used interchangeably with "antigenic determinant" or "antigenic determinant site".

The term "expression cassette", as used herein, refers to a nucleic acid construct, generated recombinantly or synthetically, with a series of specified nucleic acid elements, which permit transcription of a particular nucleic acid in a target cell.

The term "fusion protein" as used herein, relates to proteins generated by gene technology which consist of two or more functional domains derived from different proteins. A fusion protein may be obtained by conventional means (e.g. by means of gene expression of the nucleotide sequence encoding for said fusion protein in a suitable cell). The fusion protein of the invention comprises a heterologous polypeptide of interest and at least one viral structural protein, in particular at least one viral structural protein of the Triatoma virus selected from the group comprising VPO, VP1, VP2, VP3 and VP4.

The term "GK1", as used herein, relates to a synthetic antigen peptide that is comprised by the S3pvac vaccine against Porcine cysticercosis, altogether with peptides KETcl and KETcl2.

The term ' 'haematophagous", as used herein in relation to insects, relates to bloodsucking insects, in particular flying insects, which are commonly attracted to a potential living blood source, such as mammals. Haematophagous insects include, without limitation, mosquitoes, phlebotomine sand flies, simuliid black flies, horse flies and midges. In a particular embodiment, the haematophagous insect is a member of the genus Cimex, including Cimex lectularius (commonly known as bed bug), Cimex pipistrelli, Cimex pilosellus, and Cimex adjunctus. In an alternative particular embodiment, the haematophagous insect is a member of the Culicidae family (a mosquitoe). In an alternative particular embodiment, the haematophagous insect is a member of the Reduviidae family, particularly of the Triatominae subfamily, more particularly Triatoma infestans, Triatoma dimidiata, Triatoma protracta and Rhodnius prolixus.

The term "heterologous polypeptide", as used herein, relates to any polypeptide which is to be present in a VLP or virion according to the present invention, including, without limitation, an antigen, a toxin or an enzyme.

Non-limiting illustrative examples of antigens which can be used as heterologous polypeptides of interest in the present invention include:

^■ Peptides or proteins capable of (suitable or designed for) inducing an immune response against an infectious disease, such as an infectious disease in animals caused by pathogenic microorganisms of animals, including humans, for example, virus, bacteria, fungi and infectious parasites, relevant in human or animal health.

The proteins or peptides capable of inducing an immune response can be recombinant proteins or peptides, identical or similar to the natural antigens of a specific microorganism. Non- limiting illustrative examples of infectious virus include virus of the families: Arteriviridae, Retroviridae, Picornaviridae, Calciviridae, Togaviridae, Flaviridae, Coronoviridae, Rhabdoviradae, Filoviridae, Paramyxoviridae, Orthomyxoviridae, Bungaviridae, Arenaviridae, Reoviridae, Birnaviridae, Hepadnaviridae, Parvoviridae (parvovirus), Papovaviridae, Adenoviridae, Herpesviridae, Poxviridae, Iridoviridae, etc. Examples of antigens which can be used according to the present invention include but are not limited to HIV antigens, gpl20 antigen, hepatitis B surface antigen, rotavirus antigens such as VP4 and VP7, influenza virus antigens such as hemagglutinin or nucleoprotein, thymidine kinase herpes simplex antigen, etc.

Non- limiting illustrative examples of bacteria include both Gram positive bacteria, e.g., Pasteurella sp., Staphylococcus sp., Streptococcus sp., etc., and Gram negative bacteria, e.g., Escherichia coli, Pseudomonas sp., Salmonella sp., etc. Specific examples of infectious bacteria include: Helicobacter pylori, Borelia burgdorferi, Legionella pneumoplailia, Mycobacteria sp. (e.g., M. tuberculosis, M. avium, M. intracellular, M. kansaii, M. gordonae), Staphylococcus aureus, Neisseria gonorrhoeae, Neisseria meningitidis, Listeria monocytogenes, Streptococcus pyogefaes (Streptococcus Group A), Streptococcus agalactiae (Streptococcus Group B), Streptococcus (viridans group), Streptococcus faecalis, Streptococcus bovis, Streptococcus (anaerobic species), Streptococcus pneumoniae, Campylobacter sp., Enterococcus sp., Haemophilus influenzae, Bacillus aratracis, Corynebacterium diphtheriae, Corynebacterium sp., Erysipelothrix rhusiopathiae, Clostridium perfringers, Clostridium tetani, Enterobacter aerogenes, Klebsiella pneumoniae, Pasturella multocida, Bacteroides sp., Fusobacterium nucleatum, Streptobacillus moniliformis, Treponemapallidium, Treponema pertenue, Leptospira, Rickettsia, Actinomyces israelii, Chlamydia, etc.

Non-limiting illustrative examples of infectious fungi include Cryptococcus neoformans, Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis, Chlamydia trachomatis and Candida albicans.

By way of non-limiting illustration, protozoa are included among the infectious parasites, such as Plasmodium sp., protozoa causing malaria, e.g. P. falciparum, P. malariae, P. ovale, P. vivax, etc., Leishmania sp., protozoa causing leishmaniasis, e.g., L. major, L. donovani, L. infantum, L. braziliensis, L. panamensis, L. mexicana, etc., Toxoplasma gondii, Schistosoma sp., etc., as well as parasitic nematodes, such as Dirofilaria immitis, protozoa causing the Chagas disease, e.g. Tripanosoma cruzi, protozoa causing African trypanosomiasis, e.g. Tripanosoma brucei, etc. Examples of antigens for these parasites include Plasmodium spp. circumsporozoite antigen; Plasmodium spp. merozoite surface antigen; Leishmania spp. gp63, etc.

^■ Peptides or proteins associated with tumors or cancers ("tumor markers") capable of (suitable or designed for) inducing an immune response against a tumor or cancer cell therefore the heterologous polypeptide of interest can be used in the treatment of cancers by means of the stimulation of an antigen-specific immune response against a tumor antigen.

Non-limiting illustrative examples of cancers which could be potentially treated according to the teachings of the present invention include bile duct cancer, brain cancer, breast cancer, cervical cancer, choriocarcinoma, colon cancer, endometrial cancer, esophageal cancer, stomach cancer, intraepithelial neoplasias, lymphomas, liver cancer, lung cancer (e.g., small and non-small cell lung cancer), melanoma, neuroblastomas, mouth cancer, ovarian cancer, pancreatic cancer, prostate cancer, rectal cancer, sarcomas, skin cancer, testicular cancer, thyroid cancer and renal cancer, as well as other carcinomas and sarcomas.

A person skilled in the art can select tumor antigens or antigenic determinants for the treatment of cancers in view of the state of the art [Renkvist et al., Cancer Immunol. Immunother. 50:3-15 (2001)], said antigens and antigenic determinants being included within the scope of the present invention. Representative examples of said antigens or antigenic determinants include: Her2 (breast cancer); GD2 (neuroblastoma); EGF-R (malignant glioblastoma); CEA (medullary thyroid cancer); CD52 (leukemia); human melanoma gplOO protein; human melanoma melan- A/MART- 1 protein; tyrosinase; NA17-A nt protein; MAGE-3 protein; p53 protein; HPV16E7 protein; and antigenic fragments of said peptides or proteins.

^■ Peptides or proteins capable of (suitable or designed for) inducing an immune response against an allergen. As it is used in this description, the term "allergen" relates to a peptide or protein to which a subject is sensitive and causes an immune reaction, for example, allergen extracts of pollens, allergen extracts of insects, allergen extracts of food or food products, components present in saliva, insect claws or stings which induce a sensitivity reaction in a subject, components present in plants which induce a sensitivity reaction in a subject, etc. Non-limiting illustrative examples of allergens include protein extracts of pollens, e.g., of Lolium perenne, Poa pratense, Phleum pratense, Cynodon dactylon, Festuca pratensis, Dactylis glomerata, Secale cereale, Hordeum vulgare, Avena sativa, Triticum sativa, Artemisia vulgaris, Chenopodium album, Plantago lanceolata, Taraxacum vulgare, Parietaria judaica, Salsola kali, Urtica dioica, Olea europea, Platanus sp., Cupressus sp., etc.; protein extracts of insects, e.g., of Dermatophagoides pteronyssinus, Dermatophagoides farinae, Acari such as Acarus siro, Blomia tropicalis, Euroglyphus maynei, Glyciphagus domesticus, Lepidoglyphus destructor, Tyrophagus putrescentiae, etc.; protein extracts of fungi or of animal dander, e.g., Penicillium sp., Alternaria alternata, Cladosporium herbarum, dog dander, cat dander, horse dander, etc.; protein extracts of food or food products, etc.

^■ Peptides or proteins capable of (suitable or designed for) inducing a improved response against an autoantigen. As it is used herein, the term "autoantigen" relates to peptides or proteins encoded by the DNA of the subject and products generated by proteins or RNA encoded by the DNA of the subject. Examples of autoantigens are described in WO 02/56905.

The term "host cell", as used herein, refers to a cell into which a nucleic acid of the invention, such as a polynucleotide or a vector according to the invention, has been introduced. The terms "host cell" and "recombinant host cell" are used interchangeably herein. It should be understood that such terms refer not only to the particular subject cell but to the progeny or potential progeny of such a cell. Because certain modifications may occur in succeeding generations due to either mutation or environmental influences, such progeny may not, in fact, be identical to the parent cell, but are still included within the scope of the term as used herein. The term "intergenic region" or IGR, as used herein, relates to a stretch of non- coding DNA and R A sequences located between genes.

The term "immunogenic composition", as used herein, refers to a composition that elicits an immune response in a subject that produces antibodies or cell-mediated immune responses against a specific immunogen. The term "antigenic composition" refers to a composition that can be recognized by a host immune system. For example, an antigenic composition contains epitopes that can be recognized by humoral or cellular components of a host immune system.

The term "infectious disease", as used herein, relates to diseases caused by pathogens such as viruses, bacteria, fungi, protozoa, and parasites. Infectious diseases may be caused by viruses including adenovirus, cytomegalovirus, dengue, Epstein-Barr, hanta, hepatitis A, hepatitis B, hepatitis C, herpes simplex type I, herpes simplex type II, human immunodeficiency virus (HIV), human papilloma virus (HPV), influenza, measles, mumps, papova virus, polio, respiratory syncytial virus, rinderpest, rhinovirus, rotavirus, rubella, SARS virus, smallpox, viral meningitis, and the like. Infectious diseases may also be caused by bacteria including Bacillus antracis, Borrelia burgdorferi, Campylobacter jejuni, Chlamydia trachomatis, Clostridium botulinum, Clostridium tetani, Diptheria, E. coli, Legionella, Helicobacter pylori, Mycobacterium rickettsia, Mycoplasma nesisseria, Pertussis, Pseudomonas aeruginosa, S. pneumonia, Streptococcus, Staphylococcus, Vibria cholerae, Yersinia pestis, and the like. Infectious diseases may also be caused by fungi such as Aspergillus fumigatus, Blastomyces dermatitidis, Candida albicans, Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum, Penicillium marneffei, and the like. Infectious diseases may also be caused by protozoa and parasites such as chlamydia, kokzidioa, leishmania, malaria, rickettsia, trypanosoma, and the like.

The term "KETcl", as used herein, relates to a synthetic antigen peptide originally identified in a Taenia crassiceps cDNA library, and that is comprised by the S3pvac vaccine against Porcine cysticercosis, altogether with peptides GK-1 and KETcl2.

The term "KETcl2", as used herein, relates to a synthetic antigen peptide that is comprised by the S3pvac vaccine against Porcine cysticercosis, altogether with peptides GK-1 and KETcl . The term "ligand", according to the present invention, does not involve any particular size or another structural technical feature different from that of said ligand being capable of interacting and binding to the heterologous polypeptide present in the VLP and/or the infective virions of the invention; therefore, said ligand contains a region of interaction with the specific binding domain which is present in the heterologous polypeptide contained in the VLP or the virion of the invention. By way of illustration, the "heterologous polypeptide"-"ligand" pair acts as a specific binding pair, e.g., of the type of biotin-avidin, epitope-antibody or functional fragment thereof (e.g., a Fab or F(ab')2 fragment, an scFv (single-chain antibody), a chimeric antibody, etc.), etc., in which each of said peptide insert and ligand form the members of said specific binding pair, each of them containing the binding domains or the corresponding regions of interaction; thus, depending on the heterologous polypeptide present in the VLP or virion of the invention the ligand which must be present in the product of interest will be chosen, and, vice versa, depending on the ligand which is to be bound to the VLP or virion of the invention, the heterologous polypeptide which must be present in said VLP or virion will be chosen.

In a particular embodiment, the binding of the ligand to the heterologous polypeptide is performed directly. In this case, for its use in the present invention, a product of interest with the capacity to bind to said polypeptide present in the VLP or virion of the invention will be used, such that said heterologous polypeptide and product of interest form a specific binding pair. By way of non-limiting illustration, when said heterologous polypeptide comprises an amino acid tag (e.g., a histidine tag (his-tag), an arginine tag (arg-tag), etc.); likewise when said peptide insert comprises a peptide epitope which can be recognized by an antibody (e.g., c-myc-tag, etc.), the product of interest is an antibody or a functional fragment thereof; etc.

Alternatively, the binding of said ligand to the heterologous polypeptide can be performed indirectly, i.e., by means of using a "linker", or molecule comprising, on one hand, a first region of interaction with the binding domain contained in the heterologous polypeptide present in the VLP or virion and, on the other hand, a second region of interaction (binding domain) with a region of interaction present in the ligand. Thus, the product of interest binds to the VLP or virion through a structure of the type: heterologous polypeptide -linker-ligand-product of interest. Illustrative non-limiting examples of this embodiment include the use of avidin or an analog thereof (linker) when the heterologous polypeptide present in the VLP or virion comprises a BAP; etc. As used herein, the term "avidin" includes any avidin, of a eukaryotic or prokaryotic origin, and its variants which maintain the capacity to bind to biotin; in a particular embodiment, the ligand present in the conjugate of the invention comprises a monomeric variant of avidin (mAV).

The term "non-structural protein", as used in the context of the present invention in relation to a virus of the Dicistroviridae family, in particular to a Triatoma virus, relates to proteins encoded by the viral genome which do not form the capsid of said virus. The dicistrovirus genome has two open reading frames, namely ORF1 and ORF2, which encodes the non-structural protein precursor (NS) and the structural protein precursor (PI), respectively. Dicistrovirus, in particular TrV, non-structural proteins include the viral polymerase, the viral protease and the viral helicase.

The term "non-structural protein precursor" or "NS", as used in the present invention in relation to a virus of the Dicistroviridae family, in particular to a Triatoma virus, relates to the non-structural polyprotein precursor encoded by the 5' ORF1 viral genome and, particularly, corresponding to the region 549-5936 of Triatoma virus complete RNA genome according to the sequence NC 003783.1 (NCBI database as of April 28^th, 2010), to the region 549-5936 of the sequence AF 178440 from the non- structural and capsid protein precursors (NCBI database as of April 14^th, 2010), and according to Czibener C et al. 2000 J Gen Virology 81 : 1149-1154. The amino acid sequence of the TrV non-structural polyprotein precursor is located in NCBI database under accession number NP_620562.1 (1795 aa, NCBI database as of April 28^th, 2010). From this non-structural protein precursor, a RNA helicase, a peptidase and a RNA- dependent RNA polymerase (which catalyzes the synthesis of the RNA strand complementary to a given RNA template) are produced.

The term "polynucleotide", as used herein, relates to a polymer formed by a variable number of monomers wherein the monomers are nucleotides, including ribonucleotides as well as deoxyribo nucleotides. The polynucleotides include monomers modified by methylation as well as unmodified forms. The terms "polynucleotide" and "nucleic acid" are used indiscriminately in the present invention and include mRNA, cDNA and recombinant polynucleotides. As used in the present invention, polynucleotides are not limited to polynucleotides as they appear in nature, and also include polynucleotides where unnatural nucleotide analogues and inter- nucleotide bonds appear. Non- limitative examples of this type of unnatural structures include polynucleotides wherein the sugar is different from ribose, polynucleotides wherein the phosphodiester bonds 3 '-5' and 2'-5' appear, polynucleotides wherein inverted bonds (3 '-3' and 5 '-5') appear and branched structures. Also, the polynucleotides of the invention include unnatural inter-nucleotide bonds such as peptide nucleic acids (PNA), locked nucleic acids (LNA), C1-C4 alkylphosphonate bonds of the methylphosphonate, phosphoramidate, C1-C6 alkylphosphotriester, phosphorothioate and phosphorodithioate type.

The term "polypeptide", as used herein, refers to polymers of amino acids of any length. The polymer may be linear, cyclic, or branched. The polymer may comprise modified amino acids, and it may be interrupted by non-amino acids. The terms also encompass amino acid polymers that have been modified, for example, via sulfonation, glycosylation, lipidation, acetylation, phosphorylation, iodination, methylation, oxidation, proteolytic processing, phosphorylation, prenylation, racemization, selenoylation, transfer-RNA mediated addition of amino acids to proteins such as arginylation, ubiquitination, or any other manipulation, such as conjugation with a labeling component. As used herein the term "amino acid" refers to either natural and/or unnatural or synthetic amino acids, including glycine and both the D or L optical isomers, and amino acid analogs and peptidomimetics.

The term "paraflagelar rod protein" or "PFR" relates to a protein identified in T. cruci flagellum and specific to kinetoplastidis. This protein has been isolated in T. brucei and Leishmania species as well. The paraflagellar rod protein 2 (PFR2) gene was first identified in T. cruzi by pre-embedding immunoelectron microscopy with a gold- tagged secondary antibody (Saborio JL et al. 1989 J Biol Chem 264(7):4071-5), and it is believed to be a member of a multi-gene family of nearly 30 protozoan parasites. The protein has a highly organized three-dimensional structure, been found only in kinetoplastids, euglenoids, and some dino flagellates, and is responsible for parasite cell motility (Abdille MH et al. 2008 Exp Parasitol 118: 614-618).

The term "promoter", as used herein, refers to a nucleic acid fragment that functions to control the transcription of one or more genes, located upstream with respect to the direction of transcription of the transcription initiation site of the gene, and is structurally identified by the presence of a binding site for DNA- dependent RNA polymerase, transcription initiation sites and any other DNA sequences, including, but not limited to transcription factor binding sites, repressor and activator protein binding sites, and any other sequences of nucleotides known to one of skill in the art to act directly or indirectly to regulate the amount of transcription from the promoter. A "constitutive" promoter is a promoter that is active under most physiological and developmental conditions. An "inducible" promoter is a promoter that is regulated depending on physiological or developmental conditions. A "tissue specific" promoter is only active in specific types of differentiated cells/tissues. Exemplary suitable promoters according to the invention include, without limitation, polyhedrin (polh) promoter or baculo virus immediate early (iel) promoter, plO promoter or the basic protein promoter.

The term "ribozyme" or "RNA enzyme" or "catalytic RNA" refers to an RNA- based enzyme capable of targeting and cleaving particular base sequences in DNA or, more typically, RNA. According to the invention, preferred ribozymes comprise autocatalytically cleaving ribozymes. Ribozymes according to the invention include, without being limited to, hammerhead ribozyme (HamRz), Varkud satellite (VS) ribozyme, hairpin ribozyme, hepatitis delta virus (HDV) ribozyme (HDVRz) (Been MD & Wickham GS 1997 Eur J Biochem 247: 741-753), mammalian CPEB3 ribozyme, GlmS glucosamine-6-phosphate activated ribozyme and beta-globin co-transcriptional cleavage (CoTC) ribozyme. In a particular embodiment of the invention, the ribozyme is the hammerhead ribozyme (HamRz) or the hepatitis delta virus ribozyme (HDVRz).

The term "structural protein", as used in the present invention in the context of the Triatoma virus proteins, relates to those proteins forming the viral capsid of TrV. The dicistro virus genome has two open reading frames, namely ORF1 and ORF2, which encodes the non-structural proteins (NS) and the structural protein precursor (PI), respectively. TrV structural proteins include VP1, VP2, VP3 and VP4. VPO is the precursor ofVP3 and VP4.

The term "structural protein precursor" or PI, as used in the present invention in relation to Triatoma virus, relates to a protein precursor encoded by the region 6109- 8715 of Triatoma virus RNA genome according to the sequence NC_003783.1 (NCBI database as of April 28 , 2010), by the region 6109-8715 of the sequence AF 178440 from the non-structural and capsid protein precursors (NCBI database as of April 14^th, 2010), and according to Czibener C et al. 2000 J Gen Virology 81 : 1149-1154. The amino acid sequence of the structural protein precursor is located at NCBI database under accession number NP_620563.1 (868 aa, NCBI database as of April 28^th, 2010). The structural protein precursor is processed during viral biogenesis to yield the different polypeptides that form the viral capsid, namely, VP1, VP2, VP3, VP4 and VP0 (see Agirre et al, 2011, Virology, 409: 91-101).

The term "transcription regulatory region" or "transcriptional regulatory sequence", as used herein, refers to a nucleic acid sequence which is capable of governing the expression of another nucleic acid sequence operatively linked thereto, such as a gene of interest. The transcription control sequence, preferably, is a DNA sequence. The transcriptional control sequence comprises a first promoter and, optionally, at least one binding site for a transcriptional repressor wherein said first promoter and said binding site for a transcriptional repressor are arranged so that the binding of the transcriptional repressor to said binding site inhibits the transcriptional activity of the promoter.

The term "Triatoma virus", also referred to as TrV, is a viral pathogen of the blood- sucking reduviid bug Triatoma infestans (Hemiptera:Reduviidae, family Hemiptera, genus Reduviidae), the main transmitter of human Chagas disease (also called American trypanosomiasis), as well as other species of triatomine insects (popularly named kissing bugs). This disease is a major health problem in Latin America, where it is endemic and affects about eight million people, 30-40% of whom develop cardiomyopathy and/or digestive megasyndromes. The aetiological agent of Chagas disease is the protozoan parasite Trypanosoma cruzi, which infects the insect vector, which in turn infects vertebrate hosts during blood meals. TrV is a member of the Cripavirus genus (type: Cricket Paralysis Virus, CrPV) in the Dicistroviridae family, which is a family of small ssRNA(+) viruses of invertebrates. The members of the Dicistroviridae family are non-enveloped positive-sense single-stranded RNA (+ssRNA) viruses pathogenic to beneficial arthropods as well as insect pests of medical importance. The Triatoma virus belongs to the group of RNA viruses requiring a RNA polymerase for its replication, i.e. is a virus the genome of which is formed by an RNA molecule and which, unlike other R A viruses the genome of which first undergoes a reverse transcription to give rise to a DNA which is used as a template for the replication, is replicated as a result of an RNA-dependent RNA polymerase which is encoded by the genome of the virus itself.

The term "triatomine", also known as conenose bugs, kissing bugs, assassin bugs, as used herein, relates to the members of Triatominae, a subfamily of Reduviidae family. Most of the 130 or more species of this subfamily are haematophagous, i.e. feed on vertebrate blood; a very few species feed on other invertebrates. They are mainly found and widespread in the Americas, with a few species present in Asia, Africa, and Australia. These bugs usually share shelter with nesting vertebrates, from which they suck blood. In areas where Chagas disease occurs (from the southern United States to northern and southern Argentina), many of the triatomine species are insect vectors of the Chagas disease parasite Trypanosoma cruzi, but only those species that are well adapted to living with humans are considered important vectors, including Triatoma infestans, which is the main vector of the Chagas disease in Bolivia, and the Chaco region (located among Paraguay, north of Argentina and south-east of Brasil).

The terms "under the operative control" and "operatively linked" are used herein interchangeably to refer to two nucleic acids are either physically linked or are functionally linked so that at least one of the nucleic acids can act on the other nucleic acid. The transcription control sequence of the present invention and a nucleic acid sequence to be expressed, e.g., a gene of interest, are operatively linked if the expression of the nucleic acid sequence can be governed by the said transcription control sequence. Accordingly, the transcription control sequence and the nucleic acid sequence to be expressed may be physically linked to each other, e.g., by inserting the transcription control sequence at the 5 'end of the nucleic acid sequence to be expressed. Alternatively, the transcription control sequence and the nucleic acid to be expressed may be merely in physical proximity so that the transcription control sequence is functionally linked to the nucleic acid sequence to be expressed. The transcription control sequence and the nucleic acid to be expressed are, preferably, separated by not more than 1,500 bp, 500 bp, 300 bp, 100 bp, 80 bp, 60 bp, 40 bp, 20 bp, 10 bp or 5 bp.

The term "untranslated region", as used herein, also known as "UTR region", relates to either of two sections, one on each side of a coding sequence of a strand of mRNA. The "5' UTR region" (or leader sequence) is located at the 5' end of the mRNA, and it may contain elements controlling gene expression by way of regulatory elements (including binding sites for proteins that may affect stability or translation of the mRNA, and sequences that promote or inhibit translation initiation). This region begins at the transcription start site and ends one nucleotide (nt) before the start codon (usually AUG) of the coding region. The "3' UTR region" (or trailer sequence) is located at the 3' end of the mRNA, immediately following the translation termination codon. Regulatory regions within the 3' UTR can influence polyadenylation, translation efficiency, localization, and stability of the mRNA. The 3 'UTR comprises both binding sites for regulatory proteins as well as microRNAs (miRNAs). The 3'-UTR also has silencer regions which bind to repressor proteins and will inhibit the expression of the mRNA. The 3' UTR may comprise as well AU-rich elements (AREs). Proteins bind AREs to affect the stability or decay rate of transcripts in a localized manner or affect translation initiation. Furthermore, the 3' UTR comprises the sequence AAUAAA, that directs addition of several hundred adenine residues called the poly(A) tail to the end of the mRNA transcript.

The term "vaccine", as used herein, relates to an immunogenic composition for in vivo administration to a host, especially a human host, to confer protection against a disease.

The term "vector", as used herein, refers to a nucleic acid sequence comprising the necessary sequences so that after transcribing and translating said sequences in a cell a viral particle is generated. Said sequence is operably linked to additional segments that provide for its autonomous replication in a host cell of interest. Preferably, the vector is an expression vector, which is defined as a vector, which in addition to the regions of the autonomous replication in a host cell, contains regions operably linked to the genome of the invention and which are capable of enhancing the expression of the products of the genome according to the invention. The vectors of the invention can be obtained by means of techniques widely known in the art. See Brown T, "Gene Cloning" (Chapman & Hall, London, GB, 1995); Watson R, et al, "Recombinant DNA", 2nd Ed. (Scientific American Books, New York, NY, US, 1992); Alberts B, et al, "Molecular Biology of the Cell" (Garland Publishing Inc., New York, NY, US, 2008); Innis M, et al, Eds., "PCR Protocols. A Guide to Methods and Applications" (Academic Press Inc., San Diego, CA, US, 1990); Erlich H, Ed., "PCR Technology. Principles and Applications for DNA Amplification" (Stockton Press, New York, NY, US, 1989); Sambrook J, et al, "Molecular Cloning. A Laboratory Manual" (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, US, 1989); Bishop T, et al, "Nucleic Acid and Protein Sequence. A Practical Approach" (IRL Press, Oxford, GB, 1987); Reznikoff W, Ed., "Maximizing Gene Expression" (Butterworths Publishers, Stoneham, MA, US, 1987); Davis L, et al, "Basic Methods in Molecular Biology" (Elsevier Science Publishing Co., New York, NY, US, 1986), Schleef M, Ed., "Plasmid for Therapy and Vaccination" (Wiley- VCH Verlag GmbH, Weinheim, DE, 2001).

The term "viral particle", or "virion" as used herein, refers to a whole viral particle and not to a protein subunit or peptide. Viral particles consist of two or three parts: the genetic material of the virus made from either DNA or RNA; a protein coat that protects these genes; and, in some cases, an envelope of lipids that surrounds the protein coat when they are outside a cell. The shape of the viral particle ranges from simple helical and icosahedral forms to more complex structures, depending on the virus.

The term "virus-like particle", also referred to as "VLP", relates to noninfectious particles resembling viruses that do not contain any viral genetic material. VLPs are the result of the expression of viral structural proteins, such as capsid proteins, and their self-assembly.

Virus-like particles

The authors of the present invention have developed a system for antigen presentation based on VLP derived from the Triatoma virus (TrV).

Thus, in a first aspect, the present invention relates to a virus-like particle (VLP) comprising

(i) the viral structural proteins VPl, VP2, VP 3 and VP4 of a virus of the Dicistroviridae family, or the viral structural proteins VPl, VP2, and VPO of a virus of the Dicistroviridae family, or the structural protein precursor (PI) from a virus of the Dicistroviridae family, or a functionally equivalent variant any thereof, and

(ii) a heterologous polypeptide, wherein said heterologous polypeptide is provided as a fusion protein with at least one of said viral structural proteins.

In a particular preferred embodiment, the virus of the Dicistroviridae family is

TrV.

Structural protein variants of TrV- VLP

A VLP according to the invention is an oligomeric structure resulting from the assembly of a determined number of TrV capsid structural proteins. In a preferred embodiment, the VLPs are formed by the assembly of VPl, VP2, VP3 and VP4. In a still more preferred embodiment, the VLP is a structure of icosahedral symmetry, with a pseudo-triangulation number P = 3, formed by 60 protomers made up of proteins VPl (corresponding to residues 598-868 in Q9QEY5 sequence, 271 aa), VP2 (corresponding to residues 1-255 in Q9QEY5 sequence, 255 aa) and VP3 (corresponding to residues 313-597 in Q9QEY5 sequence, 285 aa), wherein VPl is located around the fivefold axes, and VP2 and VP3 alternate around the threefold icosahedral axes. In a particular embodiment, the VLP according to the invention comprises the structural proteins VPl, VP2, VP3 and VP4 of a virus of the Dicistroviridae family, preferably of a Triatoma virus (TrV), wherein said structural proteins VPl, VP2 and VP3 are in a stoichiometry of 1 : 1 : 1. In a preferred embodiment, the VLP according to the invention comprises 60 units of VPl, 60 units of VP2 and 60 units of VP3. In another preferred embodiment, the VLP is formed by an assembly of the VPl, VP2, VP3 and VP4 polypeptides. In another embodiment, the VP3 and VP4 polypeptides appear as an unprocessed polyprotein known as VPO. Thus, in this case, the VLPs result from the assembly of the VPl, VP2 and VPO polypeptides. In one embodiment, the average size of the VLPs according to the invention is about 30 nm.

In another preferred embodiment, the VLP is is formed by the structural protein precursor PI from a virus of the Dicistroviridae family, preferably of a Triatoma virus (TrV). In this particular embodiment, the average size of the VLPs according to the invention is about 50 nm.

The molecular description of the capsid of TrV is located at Protein Data Bank under accession number 3NAP (Protein Data Bank as released on May 30th, 2013; DOI: 10.2210/pdb3nap/pdb). The amino acid sequence of TrV PI capsid polyprotein precursor comprises 868 residues and is located at UniProt database under accession number Q9QEY5 (UniProt database version 40, as of April 3, 2013). The sequence of the polynucleotide encoding the nonstructural protein precursor and capsid protein precursor of Triatoma virus is located in NCBI database under accession No. AF178440 (as of April 14^th, 2000, 9010 bp). The complete genome of the Triatoma virus is located at NCBI database under accession number NC 003783.1 (as of April 28^th, 2010, 9010 bp).

In a particular embodiment, the VLP according to the present invention may further comprise one or more TrV non-structural proteins, wherein said TrV nonstructural protein is selected from the group comprising a polymerase, a protease and a helicase or a combination thereof.

One or more of the capsid proteins of the VLPs are provided as a fusion protein comprising the sequence of the capsid protein and a heterologous polypeptide. In one embodiment, the fusion protein comprises the viral structural protein and the heterologous polypeptide connected directly or indirectly, wherein the viral structural protein may be located N-terminal to the heterologous protein or wherein the viral structural protein may be located C-terminal to the heterologous protein. In another embodiment, the fusion protein comprises the sequence of the viral polypeptide which in interrupted by one or more copies and at one or more positions by the sequence of the heterologous polypeptide. In one embodiment, the fusion protein is interrupted at one position by a single copy of the heterologous polypeptide. In one embodiment, the fusion protein is interrupted at one position by several copies located in tandem of the heterologous polypeptide. In one embodiment, the fusion protein is interrupted at more than one position by one copy at each position of the same heterologous polypeptide. In one embodiment, the fusion protein is interrupted at several positions and contains at each position a different heterologous polypeptide.

It will be understood that the capsid protein variants forming the VLPs of the present invention are designed so that they are still capable of forming VLPs, i.e. that their assembly properties are not altered by the presence of the one or more copies of the heterologous polypeptide. Methods available in the art for determining whether a capsid protein variant is capable of forming VLPs are well-known in the art. For instance, a polynucleotide encoding a modified PI structural precursor protein comprising one or more modified capsid protein can be transfected into a cell together with the NS precursor protein as described in the examples of the present invention. If the modified capsid protein is capable of forming VLPs, the cell will produce VLPs that can be characterized using any technique known in the art, including the techniques used for the characterization of TrV and described by Agirre et al. {supra , native mass spectrometry (NMS) and atomic force microscopy (AFM) as described by Snidjer et al. (Snidjer J et al. 2013 Nat Chem 5(6): 502-509), techniques such as SDS-PAGE, dynamic light scattering, mass spectrometry, transmission electron microscopy as well as other techniques known in the art for detecting multiprotein assemblies such as co- immunoprecipitation, density gradient centrifugation, non-denaturing gel electrophoresis and the like. Preferably, the capsid protein variants show a viral capsid assembly activity of at least by 60%, preferably by 70%, advantageously by 80%>, more preferably by 90%>, more preferably by 95%, even more preferably by 97% and even more preferably by 98%, advantageously by 99% of the activity obtained with the complete protein. The heterologous polypeptide may have a length which can vary within a wide range, for example, between 1 and 100 amino acid residues; advantageously, said peptide insert has less than 40 amino acid residues, preferably less than 30 amino acid residues, more preferably less than 20 amino acid residues, for example, between 1 and 15 amino acids.

In a particular embodiment, the heterologous polypeptide forming part of the capsid protein variant will be capable of interacting with a polypeptide of interest, so that once the variant capsid protein forms the VLPs, the VLPs will form complexes with the polypeptide of interest. The stoichiometry of the resulting complex will depend on the capsid component which has been modified. In a preferred embodiment, the capsid protein variant is the VP1 , VP2 or VP3 polypeptide. Since the VLPs contain 60 copies of each of these polypeptides, the resulting VLP will contain up to 60 heterologous polypeptides available for binding to a polypeptide of interest. This will lead to protein complexes having a 60: 1 stoichiometry with regard to the polypeptide of interest per VLP. In another embodiment, more than one capsid protein in the VLP is provided as a capsid protein variant. In this case, the resulting complexes between VLPs and polypeptides of interest may have stoichiometries of 120: 1 , 180: 1 or more.

The product of interest can interact directly with the heterologous polypeptide or can be modified by means of the presence of a ligand showing affinity for the heterologous polypeptide such that the product of interest interacts with the heterologous polypeptide through said ligand. Therefore, the VLP of the invention comprises a heterologous polypeptide provided as a fusion protein with at least one of the viral VPO, VP1, VP2, VP3 and VP4 structural proteins, wherein said heterologous polypeptide is a first member of a binding pair.

In a particular embodiment, the heterologous polypeptide is a first member of a binding pair, and said polypeptide comprises an amino acid sequence with the capacity to bind to a second member of a binding pair such as a ligand, and does not involve any particular size or any other structural technical feature different from that of said peptide (which comprises a specific binding domain) being capable of binding to a ligand (which comprises the region of interaction corresponding to said specific binding domain present in the peptide); Therefore, virtually any heterologous peptide with the capacity to bind to a ligand can be used in the present invention. By way of non-limiting illustration, said peptide can be a member of a specific binding pair, for example, an amino acid tag (e.g., a histidine tag (his-tag), an arginine tag (arg-tag), etc.), a peptide epitope which can be recognized by an antibody (e.g., c-myc-tag, etc.), a biotin acceptor peptide (BAP), a linear domain of interaction with another protein or proteins (e.g. SH3 proteins, signal transduction proteins, etc.), a post-translational modification sequence (e.g. myristoylation, methylation, phosphorylation, etc.), a sequence of transport to a cell compartment, etc. In a particular embodiment, the heterologous polypeptide in the VLP of the invention is a first member of a binding pair, particularly a first member of a binding pair selected from the group comprising a biotin acceptor peptide (BAP), a peptide comprising the tripeptide Arg-Gly-Asp, a peptide comprising the sequence XBBXBX (SEQ ID NO:22), wherein X represents any amino acid and B represents Arg or Lys, and a peptide comprising the sequence XBBBXXBX (SEQ ID NO:23), wherein X represents any amino acid and B represents Arg or Lys.

In a particular embodiment, the heterologous polypeptide comprises the RGD motif (Ernst W et al. 2006 J Biotechnol 126: 237-240).

In a particular embodiment, the heterologous polypeptide comprises the XBBXBX motif (SEQ ID NO:22) (Verrecchio A et al. 2000 J Biol Chem 275(11): 7701-7707), wherein X represents any aminoacid and B represent a basic amino acid selected from the group consisting of Arg (R) and Lys (K). In a particular embodiment, the heterologous polypeptide comprises the XBBBXXBX motif (SEQ ID NO:23) (Verrecchio A et al. 2000 J Biol Chem 275 : 7701- 7707) wherein X represents any aminoacid and B represent a basic amino acid selected from the group consisting of Arg (R) and Lys (K).

In a particular alternative embodiment, the first member of the binding pair is the biotin acceptor peptide (BAP). Illustrative, non-limitative, examples of BAP are mentioned in EP71 1303 and include peptides comprising the following amino acid sequence (SEQ ID NO: 24):

LX1X2IX3X4X5X6KX7X8X9X10

wherein Xi is any amino acid; X₂ is an amino acid different from Leu, Val, He,

Trp, Phe, or Tyr; X₃ is Phe or Leu; X₄ is Glu or Asp; X₅ is Ala, Gly, Ser, or Thr; X₆ is Gin or Met; X₇ is He, Met, or Val; X₈ is Glu, Leu, Val, Tyr, or He; X₉ is Trp, Tyr, Val, Phe, Leu, or He; and X₁₀ is any amino acid different from Asp or Glu.

In a specific embodiment, the amino acid sequence of BAP is the following 15 amino acid sequence:

GLNDIFEAQKIEWHE (SEQ ID NO:25)

BAP is recognized by biotin ligase (BL) encoded by Escherichia coli gene BirA. The presence of this peptide in recombinant proteins allows the specific ligation of a biotin molecule to such proteins. This approach has allowed developing systems for purifying soluble proteins and protein complexes.

In an embodiment, the heterologous polypeptide comprises at least one epitope. In a more particular embodiment, the heterologous polypeptide comprises at least one epitope from an antigen selected from the group consisting of a viral antigen, a bacterial antigen, a fungal antigen, an environmental antigen or a tumor antigen. In a particular preferred embodiment, the epitope is selected from the group comprising PFR-2, PFR- 3, RAP-2, RAP-3, KETcl , GK-1 , KETcl2, HSP-70.

Viral antigens susceptible of being included in the VLP according to the invention include, without limitation, the antigens of HIV- 1 , (such as tat, nef, gpl20 or gpl60, gp40, p24, gag, env, vif, vpr, vpu, rev), human herpes virus, (such as gH, gL, gM, gB, gC, gK, gE or gD or derivatives thereof) or immediate early protein such as ICP27, ICP47, ICP4, ICP36 of VHS 1 or VHS2, cytomegalovirus, especially human cytomegalovirus, (such as gB or derivatives thereof), Epstein Barr virus (such as gp350 or derivatives thereof), varicella zoster virus (such as gpl, II, III and IE63), or of a hepatitis virus such as hepatitis B virus (for example surface antigen of hepatitis B or nuclear antigen of hepatitis), hepatitis C virus (for example nuclear antigens, El, NS3 or NS5), of paramyxovirus such as respiratory syncytial virus (such as proteins F and G or derivatives thereof), of parainfluenza virus, of rubella virus (such as proteins El and E2), measles virus, mumps virus, human papilloma virus (for example HPV6, 11, 16, 18, LI, L2, El, E2, E3, E4, E5, E6, E7), flavivirus (for example yellow fever virus, dengue virus, tick-borned encephalitis virus, Japanese encephalitis virus) or influenza virus-infected cells, such as proteins HA, NP, NA or M, or combinations thereof), rotavirus antigens (such as VP7sc and other rotavirus components), and the like (see Fundamental Virology, second edition, eds. Fields, B. N. and Knipe, D. M. (Raven Press, New York, 1991) for additional examples of viral antigens).

Bacterial antigens susceptible of being included in the VLP according to the invention include, without limitation, antigens of Neisseria spp, including N. gonorrhea and N. meningitidis (transferrin-binding proteins, lactoferrin-binding proteins, PilC and adhesins); antigens of S. pyogenes (such as M proteins or fragments thereof and C5A protease); antigens of S. agalactiae, S. mutans; H. ducreyi; Moraxella spp, including M catarrhalis, also known as Branhamella catarrhalis (such as high and low molecular weight invasins and adhesins); antigens of Bordetella spp, including B. pertussis (for example Parapertussis and B. bronchiseptica (such as pertactin, tetanus toxin or derivatives thereof, filamentous hemagglutinin, adenylate cyclase, fimbriae); antigens of Mycobacterium spp., including M. tuberculosis, M. bovis, M. leprae, M. avium, M. paratuberculosis, M. smegmatis; Legionella spp, including L. pneumophila; (for example ESAT6, antigen 85A, -B or -C, MPT 44, MPT59, MPT45, HSPIO, HSP65, HSP70, HSP 75, HSP90, PPD of 19kDa [Rv3763], PPD of 38kDa [Rv0934]); antigens of Escherichia spp, including enterotoxic E. coli (for example colonization factors, thermolabile toxin or derivatives thereof, heat stable toxin or derivatives thereof), antigens of enterohemorrhagic E. coli and enteropathogenic E. coli (for example shiga toxin-like toxin or derivatives thereof); antigens of Vibrio spp, including V. cholera (for example cholera toxin or derivatives thereof); antigens of Shigella spp, including S. sonnei, S. dysenteriae, S. flexnerii; Yersinia spp, including Y. enterocolitica (for example a Yop protein); antigens of Y. pestis, Y. pseudotuberculosis; Campylobacter spp, including C. jejuni (for example toxins, adhesins and invasins); antigens of Salmonella spp, including S. typhi, S. paratyphi, S. choleraesuis, S. enteritidis; Listeria spp., including L. monocytogenes; Helicobacter spp, including H. pylori (for example urease, catalase, vacuolating toxin); antigens of Pseudomonas spp, including P. aeruginosa; Staphylococcus spp., including S. aureus, S. epidermidis; Enterococcus spp., including E. faecalis, E. faecium; Clostridium spp., including C. tetani (for example tetanus toxin and derivative thereof); antigens of C. botulinum (for example botulinum toxin and derivative thereof), antigens of C. difficile (for example Clostridium toxins A or B and derivatives thereof); antigens of Bacillus spp., including B. anthracis (for example anthrax toxin and derivatives thereof); Corynebacterium spp., including C. diphtheriae (for example diphtheria toxin and derivatives thereof); antigens of Borrelia spp., including B. burgdorferi (for example OspA, OspC, DbpA, DbpB); antigens of B. garinii (for example OspA, OspC, DbpA, DbpB), B. afzelii (for example OspA, OspC, DbpA, DbpB), antigens of B. andersonfi (for example OspA, OspC, DbpA, DbpB), antigens of B. hermsii; Ehrlichia spp., including E. equi and the human granulocytic ehrlichiosis agent; Rickettsia spp, including R. rickettsii; Chlamydia spp., including C. trachomatis (for example MOMP, heparin-binding proteins); antigens of Chlamydia pneumoniae (for example MOMP, haparin-binding proteins), antigens of C. psittaci; Leptospira spp., including L. interrogans; Treponema spp., including T. pallidum (for example the uncommon outer membrane proteins), antigens of T. denticola, T. hyodysenteriae; Toxoplasma spp. and T. gondii (for example SAG2, SAGS, Tg34); antigens of M. tuberculosis (such as Rv2557, Rv2558, RPFs: Rv0837c, Rvl884c, Rv2389c, Rv2450, Rvl009, aceA (Rv0467), PstSl, (Rv0932), SodA (Rv3846), Rv2031c of 16 kDal, Tb Ral2, Tb Η9, Tb Ra35, Tb38-1, Erd 14, DPV, MTI, MSL, mTTC2 and hTCCl); antigens of Chlamydia (such as the high molecular weight protein (HWMP), ORF3 (document EP 366 412) and possible membrane proteins (Pmp); antigens of Streptococcus spp, including S. pneumoniae (PsaA, PspA, streptolysin, cho line-binding proteins, the pneumolysin protein antigen, and detoxified mutant derivatives thereof); antigens derived from Haemophilus spp., including H. influenzae type B (for example PRP and conjugates thereof); antigens of non-classifiable H. influenzae (such as OMP26, high molecular weight adhesins, P5, P6, D protein and D lipoprotein, and fimbrin and fimbrin-derived peptides, or multiple copy variants or the fusion proteins thereof).

Fungal antigens susceptible of being included in the VLP according to the invention include, without limitation, fungal antigenic components of Candida; fungal antigens of Histoplasma such as heat shock protein 60 (HSP60) and other fungal antigenic components of Histoplasma; of Pneumocystis spp., including P. carinii; fungal antigens of cryptococci such as capsular polysaccharides and other fungal antigenic components of cryptococci; fungal antigens of coccidia such as spherule antigens and other fungal antigenic components of coccidia; antigens of Candida spp., including C. albicans; of Cryptococcus spp., including C. neoformans; and fungal antigens of Tinea such as tricophitin and other fungal antigenic components of coccidia.

Prokaryotic antigens susceptible of being included in the VLP according to the invention include, without limitation, antigens of Plasmodium spp., such as P. falciparum and antigens derived from Plasmodium falciparum (such as RTS.S, TRAP, MSP1, AMA1, MSP3, EBA, GLURP, PFR-2, PFR-3, RAP1, RAP2, sequestrin, PfEMPl, Pf332, LSA1, LSA3, STARP, SALSA, PffiXPl, Pfs25, Pfs28, PFS27/25, Pfsl6, Pfs48/45, Pfs230 and the analogs thereof in Plasmodium spp.); as well as merozoite surface antigens, sporozoite surface antigens, circumsporozoite antigens, gametocyte/gamet surface antigens, blood type antigen pf, 55/RESA and other plasmoid antigenic components; antigens of Toxoplasma such as SAG-I, p30 and other antigenic components of Toxoplasma; schistosome antigens such as glutathione-S-transferase, paramyosin and other schistosome antigenic components; the antigen of Trichomonas spp., including T. vaginalis; antigens of Entamoeba spp., including E. histolytica; Babesia spp., including B. microti; the antigen of Leishmannia and other antigens of Leishmania such as gp63, lipophosphoglycan and their associated-protein and other antigenic components of Leishmania; antigens of Giardia spp., including G. lamblia; and antigens of Trypanosoma cruzi such as the 75-77-kDa antigen, the 56 kDa-antigen and other antigenic components of Trypanosoma.

Allergens or environmental antigens susceptible of being included in the VLP according to the invention include, without limitation, an antigen derived from allergens produced naturally such as pollen allergens (pollen allergens of trees, herb, undergrowth and grass), insect allergens (inhaled allergens, allergens from saliva and from posion), allergens from the dander and hair of animals, and food allergens. Important pollen, tree, grass and herb allergens originate from taxonomic ordes of Fagales, Oleales, Finales and Platanaceae including among other birch (Betula), alder (Alnus), hazel (Corylus), hard beam (Carpinus) and olive (Olea), cedar (Cryptomeria and Juniperus), banana (Platanus), the order of Poales including, among others, grasses of the genera Lolium, Phleum, Poa, Cynodon, Dactylis, Holcus, Phalaris, Secale and Sorghum, the orders of Asterales and Urticales including among others herbs of the genera Ambrosia, Artemisia and Parietaria. Other allergenic antigens which can be used include the allergens from house dust mites of the genera Dermatophagoides and Euroglyphus, storage mites for example Lepidoglyphys, Glycyphagus and Tyrophagus, allergens from cockroaches, midges and fleas for example Blatella, Periplaneta, Chironomus and Ctenocepphalides, allergens from mammals such as cat, dog and horse, birds, allergens from poison including those originating from bites or stings of insects such as those of the taxonomic order of Hymenoptera including bees (superfamily Apidae), wasps and ants (superfamily Formicoidae). Other allergenic antigens which can be used include allergens from the inhalation of fungi such as those of the genera Alternaria and Cladosporium.

Tumor antigens susceptible of being included in the VLP according to the invention include, without limitation, MAGE, MART-l/Melan-A, gplOO, dipeptidyl peptidase IV (DPPIV), adenosine deaminase-binding protein (ADAbp), cyclophin b, colorrectal-associated antigen (CRC)-0017-1A/GA733, carcinoembryonic antigen (CEA) and its antigenic epitopes CAP-1 and CAP-2, etv6, amll, prostate-specific antigen (PSA) and its antigenic epitopes PSA-1, PSA-2, and PSA-3, prostate-specific membrane antigen (PSMA), T-cells /CD3-C, strand receptor, MAGE family of tumor antigens (for example, MAGE-A1, MAGE-A2, MAGE -A3, MAGE-A4, MAGE-A5, MAGE-A6, MAGE-A7, MAGE-A8, MAGE-A9, MAGE-A10, MAGE-A11, MAGE- A12, MAGE-Xp2 (MAGE-B2), MAGE-Xp3 (MAGE-B3), MAGE-Xp4 (MAGE-B4), MAGE-Cl, MAGE-C2, MAGE-C3, MAGE-C4, MAGE-C5), GAGE family of tumor antigens (for example, GAGE-1, GAGE-2, GAGE-3, GAGE-4, GAGE-5, GAGE-6, GAGE-7, GAGE-8, GAGE-9), BAGE, RAGE, LAGE-1, NAG, GnT-V, MUM-1, CDK4, tyrosinase, p53, MUC family, HER2/neu, p21ras, RCAS1, -fetoprotein, E- cadherin, -catenin, 13-catenin, -catenin, pl20ctn, gplOOPmel 117, PRAME, NY-ESO-1, cdc27, adenomatous colon polyposis (ACP) protein, fodrin, conexin 37, Ig idiotype, pl5, gp75, gangliosides GM2 and GD2, viral products such as proteins of the human papillomavirus, Smad family of tumor antigens, lmp-1, PI A, EBV encoded nuclear antigen (EBNA)-l, brain glycogen phosphorylase, SSX-1, SSX-2 (HOM-MEL-40), SSX-3, SSX-4, SSX-5, SCP-1 and CT-7, and c-erbB-2, acute lymphoblastic leukemia (etv6, amll, cyclophin b), B-cells lymphoma (Ig idiotype), glioma (E-cadherin, a- catenin, 13-catenin, 7-catenin, pl20ctn), bladder cancer (p21ras), gall bladder cancer (p21ras), breast cancer (family MUC, HER2/neu, c-erbB-2), uterine cervix carcinoma (p53, p21ras), colon carcinoma (p21ras, HER2/neu, c-erbB-2, family MUC), colorrectal cancer (colorrectal-associated antigen (CRC)-0017-1A/GA733, ACP), coriocarcinoma (CEA), epithelial cell cancer (cyclophin b), stomach cancer (HER2/neu, c-erbB-2, glycoprotein ga733), hepatocellular cancer, Hodgkins's lymphoma (lmp-1, EBNA-1), lung cancer (CEA, MAGE-3, NY-ESO-1), lymphoid cell-derived leukemia (cyclophin b), melanoma (protein pl5, gp75, oncofetal antigen, gangliosides GM2 and GD2, Melan- A/MART- 1 , cdc27, MAGE-3, p21ras, gplOOPmel 117), myeloma (family MUC, p21ras), non-small cell lung carcinoma (HER2/neu, c-erbB-2), nasopharyngeal cancer (lmp-1, EBNA-1), ovarian cancer (family MUC, HER2/neu, c-erbB-2), prostate cancer (prostate-specific antigen (PSA) and its antigenic epitopes PSA-1, PSA-2 and PSA-3, PSMA, HER2/neu, c-erbB-2, glycoprotein ga733), kidney cancer (HER2/neu, c-erbB- 2), uterine cervix and esophageal squamous cell cancers (viral products such as proteins of the human papillomavirus), testicular cancer (NY-ESO-1) and T-cell leukemia (epitopes of HTLV-1).

In a particular preferred embodiment of the invention, the epitope is selected from the group comprising epitopes from PFR-2, PFR-3, RAP-2, RAP-3, KETcl, GK- l, KETcl2, HSP-70.

In a particular embodiment, the heterologous polypeptide is a PFR-2 epitope. The PFR-2 epitope is selected from sequences:

- PFR2^19"28: AVPEVTDVTL (SEQ ID NO: l),

- PFR2^156"163: KLEKIEDEL (SEQ ID NO:2), and

- PFR2^449"457: RLYKTLGQL (SEQ ID NO:3),

In a particular embodiment, the heterologous polypeptide is a PFR-3 epitope. The PFR-3 epitope is selected from sequences: - PFR3⁴^-^4Jb: FVSCCGELTV (SEQ ID NO:4),

- PFR3^475"482: DIIEQMKGV (SEQ ID NO:5), and

- PFR3^481"489: GVSGVINAL (SEQ ID NO:6).

In a particular embodiment, the heterologous polypeptide is a RAP-2 epitope. The RAP-2 epitope is selected from sequences:

- RAP-2 HABP 26220: NHF S S ADELIKYLEKTNINT (SEQ ID NO:07),

- RAP-2 HABP 26225 : IKK PFLRVLNKASTTTHAT (SEQ ID NO:08),

- RAP-2 HABP 26235: FLAEDFVELFDVTMDCYSRQ (SEQ ID NO:09), and

- RAP-2 HABP 26229: RSV NVISK KTLGLRKRSS (SEQ ID NO: 10).

In a particular embodiment, the heterologous polypeptide is a RAP-3 epitope. The RAP3 epitope comprises a sequence that is selected from sequences:

- RAP-3 HABP 33860: FNHF SN VDE AIE YLKGLNIN (SEQ ID NO: 11), and

- RAP-3 HABP 33873: KNRTYALPKVKGFRFLKQLF (SEQ ID NO: 12). In a particular embodiment, the heterologous polypeptide is a KETcl epitope which comprises the sequence APMSTPSATSVR (SEQ ID NO: 17).

In a particular embodiment, the heterologous polypeptide is a GK-1 epitope which comprises the sequence GYYYPSDPNTFTAPPYSA (SEQ ID NO: 18).

In a particular embodiment, the heterologous polypeptide is a KETcl 2 epitope which comprises the sequence GNLLLSCL (SEQ ID NO: 19).

In a particular embodiment, the heterologous polypeptide is a HSP70 epitope which comprises a sequence selected from TLLTIDGGI (SEQ ID NO:20) and TLQPVERV (SEQ ID NO:21).

In a particular embodiment, wherein the capsid variant proteins contain a first member of the binding pair, the resulting VLP is bound to a second member of a binding pair via interaction of said second member of a binding pair with the first member of a binding pair comprised by the VLP. In a particular embodiment, the first member of the binding pair is the biotinylated BAP and the second member of the binding pair is a molecule comprising a biotin-binding region. Molecules comprising a biotin-binding region according to the invention include, without limitation, avidin, an avidin analog, streptavidin, and streptavidin analog. As previously mentioned, the VLP according to the invention comprises a heterologous polypeptide, wherein said polypeptide allows the formation of complexes between the VLP and a product of interest. This product of interest can interact directly with the heterologous polypeptide or can be modified by means of the presence of a ligand showing affinity for the heterologous polypeptide such that the product of interest interacts with the heterologous polypeptide through said ligand.

As used herein, the term "product of interest" includes any molecule with biological activity in its broadest sense, i.e., any substance which, when administered to a subject, interacts with its receptor in the site of action and exerts a determined effect. The product of interest can be of a peptide (protein) nature or a non-peptide nature, for example, a protein, an antibody or a functional fragment thereof, a hormone, an enzyme, a lipid, a sugar, a non-peptide drug, a nucleic acid, etc.

Illustrative non-limiting examples of products of interest include any type of bioactive molecules such as synthetic molecules (e.g., acetylsalicylic acid, paracetamol, tranexamic acid, metoprolol, etc.), natural products (e.g., taxol, taxane derivatives, paclitaxel, epibatidine, atropine, etc.), oligonucleotides (e.g., augmerosen), aptamers (e.g., pegaptanib), proteins (e.g., interleukins, interferons, erythropoietins, coagulation factors, insulins, etc.), antibodies (e.g., erbitux, rituxan, herceptin, avastin, remicade, humira, xolair, etc.), peptides (e.g., calcitonins, vasopressin analogs (e.g., arginine vasopressin, desmopressin acetate, etc.), insulin polypeptides (e.g., humulin, insulin aspart, etc.), growth hormones (e.g., somatotropin, sermorelin, recombinant growth factor, etc.), gonadotropin polypeptides (e.g., urofollitropin, recombinant follicle- stimulating hormone, etc.), gonadotropins (e.g., chorionic gonadotropins), thyrotropic hormone analogs, somatostatin analogs (e.g., octreotide, lanreotide acetate, etc.), parathyroid hormone polypeptides (e.g., teriparatide acetate, recombinant parathyroid hormone (1-84), etc.), alpha-atrial natriuretic peptide, brain natriuretic peptide (e.g., nesiritide, etc.), thyroid hormone (e.g., thyrotropin, etc.), luteinizing hormone polypeptides (e.g., lutropin alfa, etc.), glucagon-like peptide-1 (GLP1) analogs (e.g., exenatide, etc.), corticotropin polypeptides (e.g., corticotropin, etc.), corticotropin release factor, gastrin analogs, peptides for radiation treatment (e.g., lanreotide, etc.), peptide vaccines (e.g., malaria, cancer, HIV, HVB, multiple sclerosis, etc.), hormones, enzymes, lipids, sugars, nucleic acids (DNA, RNA, PNA, etc.), e.g., oligonucleotides, polynucleotides, genes, interfering RNA, etc.

In a particular embodiment, said product of interest is of a peptide nature; in this case, its size can vary within a wide range, from a few amino acids to hundreds of amino acids. Said peptide product of interest can be virtually any peptide, regardless of its origin (eukaryotic, prokaryotic, viral, etc.), which can be recombinantly expressed, for example, a peptide antigen, such as a viral, bacterial, microbial, tumor antigen, etc., against which an immune response is to be induced in a subject (such as an animal, including humans); an enzyme, such as an enzyme intended to supplement a function in which an organism is deficient; a peptide drug intended to prevent or treat a pathological condition in a subject; an antibody or a functional fragment thereof; etc. Therefore, in a particular embodiment, said peptide product of interest is a peptide useful in vaccination, therapy or diagnosis, such as an epitope or antigenic determinant capable of inducing an immune response in a subject (e.g., animals, including humans) against diseases caused by viruses, bacteria, parasites or any other type of microorganism, or against tumor diseases, or is a peptide useful in therapy (prevention and/or treatment) of other pathologies, for example, heparin, a cell growth factor, an interleukin, an interferon, a protein of interaction with a membrane receptor, a peptide of interaction with a specific cell marker, etc.

In another particular embodiment, said product of interest is a product of a non- peptide nature. Said product of interest of a non-peptide nature can be virtually any compound of a non-peptide nature, for example, a polynucleotide, a non-peptide antigen, such as allergens, viral, bacterial, microbial, tumor antigen, etc., against which an immune response is to be induced in a subject (such as an animal, including humans); a non-peptide drug intended to prevent or treat a pathological condition in a subject; a lipid with the capacity to interact with a molecule of interest; a sugar with the capacity to interact with a molecule of interest; etc. Therefore, in a particular embodiment, said non-peptide product of interest is a compound useful in vaccination, therapy or diagnosis, such as a non-peptide antigenic determinant capable of inducing an immune response in a subject (e.g., animals, including humans) against diseases caused by viruses, bacteria, parasites or any other type of microorganism, or against tumor diseases, or is a compound useful in the therapy (prevention and/or treatment) of pathologies of another type.

Alternatively, the product of interest can interact with the heterologous polypeptide of the VLP of the invention through a ligand.

As used herein, the term "ligand" relates to a molecule which is capable of interacting specifically and binding to the heterologous polypeptide insert present in the VLPs of the invention. The product of interest can be of a peptide (protein) nature or a non-peptide nature.

As used herein, the expression "capable of interacting specifically" or "specific interaction" describes the interaction between a first species and a second species characterized in that the nature of the binding is such that an antibody, a receptor or a nucleic acid binding protein binds to its corresponding binding partner but does not substantially bind to other species. Likewise, as used herein, the term "binding" or "binding to" means the physical association between a first species and a second species, for example, the binding of a ligand by a receptor, the binding of an antigen by an antibody, the binding of a nucleic acid by a nucleic acid binding protein, etc.

The term "ligand" does not involve any particular size or another structural technical feature different from that of said ligand being capable of interacting and binding to the heterologous polypeptide present in the VLP of the invention; therefore, said ligand contains a region of interaction with the specific binding domain which is present in the heterologous polypeptide contained in the VLP of the invention. By way of illustration, the "heterologous polypeptide"-"ligand" pair acts as a specific binding pair, e.g., of the type of biotin-avidin, epitope-antibody or functional fragment thereof (e.g., a Fab or F(ab')2 fragment, an scFv (single-chain antibody), a chimeric antibody, etc.), etc., in which each of said peptide insert and ligand form the members of said specific binding pair, each of them containing the binding domains or the corresponding regions of interaction; thus, depending on the heterologous polypeptide present in the VLP of the invention the ligand which must be present in the product of interest will be chosen, and, vice versa, depending on the ligand which is to be bound to the VLP of the invention, the peptide insert which must be present in said VLP will be chosen.

In a particular embodiment, the binding of the ligand to the heterologous polypeptide insert is performed directly. In this case, for its use in the present invention, a product of interest with the capacity to bind to said heterologous polypeptide present in the VLP of the invention will be used, such that said polypeptide insert and product of interest form a specific binding pair. By way of non-limiting illustration, when said polypeptide insert comprises an amino acid tag (e.g., a histidine tag (his-tag), an arginine tag (arg-tag), etc.); likewise when said polypeptide insert comprises a peptide epitope which can be recognized by an antibody (e.g., c-myc-tag, etc.), the product of interest is an antibody or a functional fragment thereof; etc.

Alternatively, the binding of said ligand to the peptide insert can be performed indirectly, i.e., by means of using a "linker", or molecule comprising, on one hand, a first region of interaction with the binding domain contained in the heterologous polypeptide present in the VLP and, on the other hand, a second region of interaction (binding domain) with a region of interaction present in the ligand. Thus, the product of interest binds to the VLP through a structure of the type: heterologous polypeptide- linker-ligand-product of interest. Illustrative non-limiting examples of this embodiment include the use of avidin or an analog thereof (linker) when the peptide insert present in the VLP comprises a BAP; etc. As used herein, the term "avidin" includes any avidin, of a eukaryotic or prokaryotic origin, and its variants which maintain the capacity to bind to biotin; in a particular embodiment, the ligand present in the conjugate of the invention comprises a monomeric variant of avidin (mAV).

In an alternative or additional embodiment, the invention also contemplates that the VLP comprises a heterologous polypeptide easily detectable including, without limitation, luciferase, (green/red) fluorescent protein and variants thereof, such as EGFP (enhanced green fluorescent protein), RFP (red fluorescent protein, such as DsRed or DsRed2), CFP (cyan fluorescent protein), BFP (blue green fluorescent protein), YFP (yellow fluorescent protein), β-galactosidase or chloramphenicol acetyltransferase, and the like.

Alternatively or additionally, the heterologous polypeptide can be a polypeptide of therapeutic interest such that the VLPs of the present invention can be used for the in vitro expression of said polypeptide or for the treatment of diseases requiring the expression of said polypeptide. Examples of sequences of therapeutic interest which can be incorporated in the VLP of the invention include but are not limited to those polypeptides encoded by genes or cDNAs encoding erythropoietin (EPO), leptins, corticotropin-releasing hormone (CRH), growth hormone-releasing hormone (GHRH), gonadotropin-releasing hormone (GnRH), thyrotropin-releasing hormone (TRH), prolactin-releasing hormone (PRH), melatonin-releasing hormone (MPvH), prolactin- inhibiting hormone (PIH), somatostatin, adrenocorticotropic hormone (ACTH), somatotropin or growth hormone (GH), luteinizing hormone (LH), follicle- stimulating hormone (FSH), thyrotropin (TSH or thyroid-stimulating hormone), prolactin, oxytocin, antidiuretic hormone (ADH or vasopressin), melatonin, Mullerian inhibiting factor, calcitonin, parathyroid hormone, gastrin, cholecystokinin (CCK), secretin, insulin-like growth factor type I (IGF-I), insulin-like growth factor type II (IGF-II), atrial natriuretic peptide (ANP), human chorionic gonadotropin (HCG), insulin, glucagon, somatostatin, pancreatic polypeptide (PP), leptin, neuropeptide Y, renin, angiotensin I, angiotensin II, factor VIII, factor IX, tissue factor, factor VII, factor X, thrombin, factor V, factor XI, factor XIII, interleukin 1 (IL-1), interleukin 2 (IL-2), tumor necrosis factor alpha (TNF- a), interleukin 6 (IL-6), interleukin 8 (IL-8 and chemokines), interleukin 12 (IL-12), interleukin 16 (IL-16), interleukin 15 (IL-15), interleukin 24 (IL-24), interferons alpha, beta, gamma, CD3, ICAM-1, LFA-1, LFA-3, chemokines including RANTES l , MIP- l , ΜΙΡ-Ιβ, nerve growth factor (NGF), platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-beta), bone morphogenetic proteins (BMPs), fibroblast growth factors (FGF and KGF), epidermal growth factor (EGF and related factors), vascular endothelial growth factor (VEGF), granulocyte colony-stimulating factor (GM-CSF), glial growth factor, keratinocyte growth factor, endothelial growth factor, alpha 1 -antitrypsin, tumor necrosis factor, granulocyte-macrophage colony- stimulating factor (GM-CSF), cardiotrophin-1 (CT-1), oncostatin M (OSM), amphiregulin (AR), cyclosporine, fibrinogen, lactoferrin, tissue-type plasminogen activator (tPA), chymotrypsin, immunoglobins, hirudin, superoxide dismutase, imiglucerase, β-Glucocerebrosidase, alglucosidase-a, a-L-iduronidase, iduronate-2- sulfatase, galsulfase, human a-galactosidase A, a-1 proteinase inhibitor, lactase, pancreatic enzymes (lipase, amylase, protease), adenosine deaminase, immunoglobulins, albumin, botulinum toxins type A and B, collagenase, human deoxyribonuclease I, hyaluronidase, papain, L-asparaginase, lepirudin, streptokinase, cell transforming factor beta (TGF-β) inhibitor peptides such as those described in WO0331155, WO200519244 and WO0393293, the content of which is incorporated in the present invention by reference, expression cassettes suitable for the transcription of interference R A molecules (shRNA, siRNA, miRNA, RNA of modified Ul ribonucleoproteins) .

The invention contemplates also VLPs wherein the TrV VP1, VP2, VP3, and VP4, capsid proteins are not the native proteins as they appear in the TrV in nature but functionally equivalent variants thereof.

In the context of the invention, "functionally equivalent variant" of a structural protein of the Triatoma virus is understood as any sequence having additions, substitutions, deletions or combinations thereof in its amino acid sequence and/or which has been chemically modified with respect to said sequence and which substantially maintains the function of said structural protein, particularly the capacity of assembling into a viral capsid. Suitable assays for determining viral capsid assembly capacity are known by the skilled person and include electron microscopy, criomicroscopy, etc. as disclosed for example in Bottcher B et al. 1998 EMBO J 17(23):6839-45; and Yadav SS et al. 2012 Virology 429(2): 155-162. Preferably, the functional equivalent variants of the structural proteins of the Triatoma virus show the aforementioned viral capsid assembly activity at least by 60%, preferably by 70%, advantageously by 80%>, more preferably by 90%>, more preferably by 95%, even more preferably by 97% and even more preferably by 98%, advantageously by 99%.

In the context of the invention, "functional equivalent variants" of the nonstructural protein precursor NS of the Triatoma virus show the helicase, peptidase and/or RNA-dependent RNA polymerase activities at least by 60%, preferably by 70%, advantageously by 80%, more preferably by 90%, more preferably by 95%, even more preferably by 97% and even more preferably by 98%, advantageously by 99%.

The VLP according to the present invention may or may not contain a product of interest bound to the heterologous polypeptide present in said VLP through a ligand with the capacity to bind to said heterologous polypeptide, or alternatively, through a dual linker, i.e., with two different binding domains, one with the capacity to bind to said heterologous polypeptide and another one with the capacity to bind to said ligand to which the product of interest is bound.

Location of the heterologous polypeptide in the structural protein The heterologous polypeptide insert can be found in any position with respect to the structural protein, in particular TrV structural protein, to which it is fused. Thus, the invention contemplates a fusion protein comprising the structural protein the C-terminus of which is fused to the N-terminus of the heterologous polypeptide, as well as a fusion protein comprising the structural protein the N-terminus of which is fused to the C- terminus of the heterologous polypeptide.

In another embodiment, the heterologous polypeptide is inserted inside the amino acid sequence of at least one viral structural protein, wherein said viral structural protein is TrV VP1, VP2, VP3, VP4 or VPO. The introduction of said heterologous polypeptide in said at least one TrV structural protein must be performed such that it does not substantially alter the self-assembly capacity of said structural protein; and, furthermore, said heterologous polypeptide must be located in a region of said capsid structural protein accessible to the solvent in the oligomeric structures formed after the self-assembly of the capsid.

In this particular embodiment, given that the heterologous polypeptide is inserted inside the amino acid sequence of at least one TrV structural capsid protein, the fusion protein maintains the amino and carboxyl termini of said structural capsid protein and the heterologous polypeptide is included inside the amino acid sequence of said structural capsid protein, for example, between two contiguous amino acids of said capsid protein or, alternatively, replacing one or more amino acids of said capsid protein. By way of illustration, in a particular embodiment, said heterologous polypeptide is located between 2 contiguous amino acids of the structural capsid protein, i.e., between the "x" residue and the "x+1" residue of the amino acid sequence of said structural capsid protein; whereas, in another particular embodiment, due to the strategy followed for the introduction of the heterologous polypeptide, one or more residues located in the regions adjacent to the point of insertion can be lost. Furthermore, given that the heterologous polypeptide must be located in a region of said structural capsid protein accessible to the solvent in the VLPs formed according to the invention, the heterologous polypeptide must be inserted in a suitable region. Particularly suitable regions of the structural protein for introducing the peptide insert are the loops present in said structural capsid proteins, particularly those loops which, in the oligomeric structures that they form, are exposed to the solvent. To choose the suitable site of insertion of the heterologous polypeptide of interest according to the invention in a TrV structural capsid protein it is convenient to know the atomic structure of the capsid protein to be genetically modified. The atomic structure of a structural protein can be determined by means of using X-ray diffraction. The use of suitable computer programs, such as the UCSF Chimera program (http://www.cgl.ucsf.edu/chimera/) for example, allows locating the regions of the protein under study which can potentially be genetically modified. These merely theoretical predictions initially serve to: i) discard regions that are not exposed to the solvent; and ii) identify regions the modification of which could cause a serious alteration in the secondary structure of the protein. Once the atomic structure of the capsid protein is known, a strategy can be designed to incorporate the peptide insert in the suitable site, for example, in a loop of said capsid protein which is exposed to the solvent when said structural protein is assembled with the rest of the structural proteins of the TrV and forms the oligomeric structure.

In a particular embodiment, said structural protein for the insertion of the heterologous polypeptide of interest is selected from the group comprising VPl, VP2, VP3, VP4, VPO and variants thereof. Sequences of VPl, VP2 and VP3 are located under Accession No. Q9QEY5 (UniProt database version 40, as of April 3, 2013, residues 1-255 corresponding to VP2, residues 313-597 corresponding to VP3 and residues 598-868 corresponding to VPl) and VP4 sequence is described in Agirre J et al. 2011 Virology 409: 91-101 (residues 256-312 in Q9QEY5). In this case, for the purpose of designing the strategy for introducing the heterologous polypeptide in the suitable region, an in-depth study of the atomic structure of said TrV capsid proteins, which has already been described (Squires G et al. 2013 Acta Cryst D69: 1026-1037) can be followed.

In a particular embodiment, the heterologous polypeptide of interest is inserted inside the amino acid sequence of at least one TrV structural protein, is bound to the amino terminal end of at least one TrV structural protein and/or is bound to the carboxy terminal end of at least one TrV structural protein wherein said at least one TrV structural protein is the same TrV structural protein or is a different TrV protein.

In a particular embodiment, regions for insertion/substitution in TrV structural proteins include the following regions: 1) in VPl protein

- from Ala681 to Trp688 according to Q9QEY5 Uniprot sequence (UniProt database version 40, as of April 3, 2013) (corresponding to Ala84 to Trp91 in VPl sequence): stretch of 9 amino acid long located between two structural β-strands Pro 675-Tyr679 according to Q9QEY5 Uniprot sequence (Pro78-Tyr82 in VPl sequence).

- from Asp841 to Thr854 according to Q9QEY5 Uniprot sequence (Asp244 to Thr257 in VPl sequence): stretch of 19 amino acids long located between two structural a-helixes Ala836-Arg840 in Q9QEY5 (Ala239-Arg243 in VPl sequence), and Phe855- Leu860 in Q9QEY5 (Phe258-Leu263 in VPl sequence).

- from Leu860 in Q9QEY5 sequence (Leu263 in VPl sequence): stretch at the protein C-terminal end (aa chain is unstructured from Ser861 (Ser264 in VPl sequence)). This region is preceded by an a-helix Thr854-Tyr859 (Thr257-Tyr262 in VPl sequence).

2) in VP2 protein:

- from Thr97 to Lysl03 according to Q9QEY5 Uniprot sequence: stretch between two structural β-strands (Phe89-Asn96, and Glul04).

- from Ala251 according to Q9QEY5: C-terminal region pointing to the capsid exterior and after a structural β - strand (Ala230-Leu245 according to Q9QEY5).

3) in VP3 protein:

- from Thr498 to Gln531 according to Q9QEY5 (Thrl86 to Gln219 in VP 3 sequence): stretch between two structural β-strands Thr486-Val492 in Q9QEY5 (Thrl74-Vall80 in VP3 sequence), and Gly535-Ala541 in Q9QEY5 (Gly223-Ala229 in VP3 sequence),

- from Glu586 according to Q9QEY5 (Glu274 in VP3 sequence): C-terminal region located after a structural β-strand Ser583-Glu586 (Ser271-Glu274 in VP 3 sequence), and aa chain with unknown structure after Pro588 (Pro276 in VP3 sequence).

Therefore, in a particular embodiment, the heterologous polypeptide is located in VPl structural protein, replacing the VPl region from Ala681 to Trp688, replacing the VPl region from Asp841 to Thr854 and/or by after Leu860 in

VPl protein, according to Q9QEY5 Uniprot sequence, in VP2 structural protein, replacing the VP2 region from Thr97 to Lysl03, and/or after Ala251 in VP2 protein, according to Q9QEY5 Uniprot sequence,

in VP3 structural protein, replacing the VP3 region from Thr498 to Gln531, and/or after Glu586 in VP3 protein, according to Q9QEY5 Uniprot sequence, and/or

in VP4 protein, in any region of its aminoacid sequence.

In another particular embodiment, said heterologous polypeptide is bound to the amino or carboxyl terminus of at least one TrV capsid structural protein. Therefore, in a particular embodiment, said heterologous polypeptide is bound to the amino terminus of said TrV capsid protein, whereas, in another particular embodiment, said heterologous polypeptide is bound to the carboxyl terminus of said TrV capsid protein. In another particular embodiment, the TrV capsid protein comprises two heterologous polypeptide bound to said protein, wherein each of said heterologous polypeptide is bound to each of the amino and carboxyl termini of said capsid protein.

In another particular embodiment, the VLP of the invention comprises more than one heterologous polypeptide, wherein said more than one heterologous polypeptide is provided as a fusion protein with one or more TrV structural proteins. In a particular embodiment, the VLP of the invention comprises several heterologous polypeptides, wherein said several heterologous polypeptides are provided as fusion proteins with one or more TrV structural proteins.

Polynucleotide encoding a fusion protein (first polynucleotide of the invention). Vectors and host cells thereof

In a further aspect, the present invention relates to a polynucleotide (first polynucleotide of the invention) encoding a fusion protein, wherein said fusion protein comprises

(i) a structural protein from a virus of the Dicistroviridae family selected from the group consisting of VP1, VP2, VP3, VP4 and VP0, or a functionally equivalent variant thereof, and a heterologous polypeptide, or (ii) a structural protein precursor (PI) from a virus of the Dicistroviridae family, or a functionally equivalent variant thereof, and a heterologous polypeptide.

In a particular preferred embodiment, the virus of the Dicistroviridae family is the TrV.

The structural proteins of viruses of the Dicistroviridae family, particularly TrV, have been previously described in the context of the VLP of the invention and include VP1, VP2, VP3, VP4 and VPO. In a particular embodiment, the polynucleotide of the invention encodes a fusion protein comprising the complete Triatoma virus structural protein precursor PI, or a functional equivalent variant thereof. TrV structural proteins precursor PI is encoded by the TrV ORF2 viral genome (nucleotides 6109-8715, according to Czibener C et al. 2000 J Gen Virology 81 : 1149-1154, and GenBank accession number AF 178440). In a more particular embodiment, the polynucleotide of the invention further comprises a nucleotide sequence encoding the non-structural protein NS of the Triatoma virus according to GenBank accession number AF 178440 or a functionally equivalent variant thereof. TrV polyprotein precursor of non- structural proteins is encoded by the 5' ORF1 TrV viral genome (nucleotides 549-5933, according to Czibener C et al. 2000 J Gen Virology 81 : 1149-1154, and GenBank accession number AF 178440). TrV non- structural proteins include the viral polymerase, the viral protease and the viral helicase.

In a particular embodiment, the heterologous polypeptide comprised by the fusion protein encoded by the first polynucleotide of the invention is inserted inside the amino acid sequence of at least one TrV structural protein, is bound to the amino terminal end of at least one TrV structural protein and/or is bound to the carboxy terminal end of at least one TrV structural protein wherein said at least one TrV structural protein is the same TrV structural protein or is a different TrV protein.

In a particular embodiment, the heterologous polypeptide comprised by the fusion protein encoded by the polynucleotide of the invention is located at a position selected from the group consisting of:

in VP1 structural protein, replacing the VP1 region from Ala681 to Trp688, - in VP1 structural protein, replacing the VP1 region from Asp841 to Thr854 in VP1 structural protein, after Leu860,

in VP2 structural protein, replacing the VP2 region from Thr97 to Lysl03, in VP2 structural protein, after Ala251 ,

in VP3 structural protein, replacing the VP3 region from Thr498 to Gln531 , in VP3 structural protein, after Glu586, and/or

in VP4, in any region of its amino acid sequence.

Heterologous polypeptides according to the invention have been previously described in the context of the VLP of the invention. In a particular embodiment, the heterologous polypeptide is a first member of the binding pair. In an alternative particular embodiment, the heterologous polypeptide comprises at least one epitope.

Binding pairs according to the invention have been described previously as well. In a particular embodiment, the first member of the binding pair is selected from the group consisting of a biotin acceptor peptide (BAP), a peptide comprising the tripeptide Arg-Gly-Asp, a peptide comprising the sequence XBBXBX (SEQ ID NO:22), wherein X represents any aminoacid and B represents Arg or Lys, and a peptide comprising the sequence XBBBXXBX (SEQ ID NO:23), wherein X represents any aminoacid and B represents Arg or Lys.

In a particular embodiment, the heterologous polypeptide comprises a sequence comprising the RGD motif (Ernst W et al. 2006 J Biotechnol 126: 237-240), that comprises the tripeptide arginyl-glycyl-aspartic acid (Arg-Gly-Asp).

In a particular embodiment, the heterologous polypeptide comprises the XBBXBX motif (SEQ ID NO:22) (Verrecchio A et al. 2000 J. Biol. Chem. 275(11): 7701-7707), wherein X represents any aminoacid and B represent a basic amino acid selected from the group consisting of Arg (R) and Lys (K).

In a particular embodiment, the heterologous polypeptide comprises the XBBBXXBX motif (SEQ ID NO:23) (Verrecchio A et al. 2000, J. Biol. Chem. 275(11): 7701-7707) wherein X represents any aminoacid and B represent a basic amino acid selected from the group consisting of Arg (R) and Lys (K).

In a particular embodiment, the epitope is selected from an antigen selected from the group comprised by a viral antigen, a bacterial antigen, a fungal antigen, an environmental antigen or a tumor antigen.

In a particular embodiment, the epitope is selected from the group comprising epitopes from PFR-2, PFR-3, RAP-2, RAP-3, KETcl, GK-1, KETcl2 and HSP-70. In a particular embodiment, the PFR-2 epitope of the VLP of the invention comprises a sequence that is selected from sequences:

- PFR2^{19 28}: AVPEVTDVTL (SEQ ID NO:01),

- PFR2^156"163: KLEKIEDEL (SEQ ID NO:02), and

- PFR2^449"457: RLYKTLGQL (SEQ ID NO:03),

In a particular embodiment, the PFR-3 epitope of the VLP of the invention comprises a sequence that is selected from sequences:

- PFR3^{428 436}: FVSCCGELTV (SEQ ID NO:04),

- PFR3^{475 482}: DIIEQMKGV (SEQ ID NO:05), and

- PFR3^481"489: GVSGVINAL (SEQ ID NO:06).

In a particular embodiment, the RAP-2 epitope of the VLP of the invention comprises a sequence that is selected from sequences:

- RAP-2 HABP 26220: NHF S S ADELIKYLEKTNINT (SEQ ID NO:07),

- RAP-2 HABP 26225 : IKK PFLRVLNKASTTTHAT (SEQ ID NO:08), - RAP-2 HABP 26235: FLAEDFVELFDVTMDCYSRQ (SEQ ID NO:09), and

- RAP-2 HABP 26229: RSVNNVISKNKTLGLRKRSS (SEQ ID NO: 10).

In a particular embodiment, the RAP-3 epitope of the VLP of the invention comprises a sequence that is selected from sequences:

- RAP-3 HABP 33860: FNHF SN VDE AIE YLKGLNIN (SEQ ID NO: 11), and

- RAP-3 HABP 33873: KNRTYALPKVKGFRFLKQLF (SEQ ID NO: 12).

In a particular embodiment, the epitope KETcl of the VLP of the invention comprises the sequence APMSTPSATSVR (SEQ ID NO: 17).

In a particular embodiment, the epitope GK-1 of the VLP of the invention comprises the sequence GYYYPSDPNTFTAPPYS A (SEQ ID NO : 18).

In a particular embodiment, the epitope KETcl2 of the VLP of the invention comprises the sequence GNLLLSCL (SEQ ID NO: 19).

In a particular embodiment, the epitope from HSP70 of the VLP of the invention is selected from sequences TLLTIDGGI (SEQ ID NO:20) and TLQPVERV (SEQ ID NO:21).

The polynucleotide encoding a fusion protein comprising a structural protein from TrV and a heterologous polypeptide according to the present invention may be conveyed in a vector in order to allow adequate propagation of said polynucleotide. Therefore, the invention also contemplates that the polynucleotide encoding a fusion protein comprising a structural protein from the Triatoma virus and a heterologous polypeptide as described above is comprised by a vector (vector of the invention). Thus, in another aspect, the invention relates to a vector comprising a polynucleotide encoding a fusion protein comprising a structural protein from the Triatoma virus and a heterologous polypeptide, wherein said polynucleotide has been described previously.

A person skilled in the art will understand that there is no limitation as regards the type of vector which can be used because said vector can be a cloning vector suitable for propagation and for obtaining the polynucleotides or suitable gene constructs or expression vectors in different heterologous organisms suitable for purifying the conjugates. Thus, suitable vectors according to the present invention include prokaryotic expression vectors (e.g. pUC18, pUC19, Bluescript and their derivatives), mpl8, mpl9, pBR322, pMB9, CoIEl, pCRl, RP4, phages and shuttle vectors (e.g. pSA3 and pAT28), yeast expression vectors (e.g. vectors of the type of 2 micron plasmids), integration plasmids, YEP vectors, centromeric plasmids and the like, insect cell expression vectors (e.g. the pAC series and pVL series vectors), plant expression vectors, such as vectors of expression in plants (e.g. pIBI, pEarleyGate, pAVA, pCAMBIA, pGSA, pGWB, pMDC, pMY, pORE series vectors), and eukaryotic expression vectors based on viral vectors (e.g. adenoviruses, viruses associated to adenoviruses as well as retroviruses and lentiviruses), as well as non-viral vectors (e.g. pSilencer 4.1-CMV (Ambion®, Life Technologies Corp., Carlsbad, CA, US), pcDNA3, pcDNA3.1/hyg pHCMV/Zeo, pCR3.1, pEFl/His, pIND/GS, pRc/HCMV2, pSV40/Zeo2, pTRACER-HCMV, pUB6/V5-His, pVAXl, pZeoSV2, pCI, pSVL and pKS V- 10, pBPV- 1 , pML2d and pTDTl).

Vectors may further contain one or more selectable marker sequences suitable for use in the identification of cells which have or have not been transformed or transfected with the vector. Markers include, for example, genes encoding proteins which increase or decrease either resistance or sensitivity to antibiotics or other compounds (e.g. hyg encoding hygromycin resistance (GenBank accession no. AF025746; or AF025747) and Kan^R (GenBank accession no. U75323), genes which encode enzymes whose activities are detectable by standard assays known in the art (e.g. β-galactosidase or luciferase), and genes which visibly affect the phenotype of transformed or transfected cells, hosts, colonies or plaques such as various fluorescent proteins (e.g. green fluorescent protein, GFP). Alternatively, the vectors of the present invention may carry a non-antibiotic selection marker, including, for instance, genes encoding a catabolic enzyme which enables the growth in medium containing a substrate of said catabolic enzyme as a carbon source. An example of such a catabolic enzyme includes, but is not restricted to, lacYZ encoding lactose uptake and beta- galactosidase (GenBank accession nos. J01636, J01637, K01483, or K01793). Other selection markers that provide a metabolic advantage in defined media include, but are not restricted to, galTK (GenBank accession no. X02306) for galactose utilization, sacPA (GenBank accession no. J03006) for sucrose utilization, trePAR (GenBank accession no. Z54245) for trehalose utilization and xylAB (GenBank accession nos. CAB 13644 and AAB41094) for xylose utilization. Alternatively, the selection can involve the use of antisense mRNA to inhibit a toxic allele, for instance the sacB allele (GenBank accession no. NP 391325).

Vectors according to the invention can also comprise at least one heterologous sequence encoding a cytokine, which is used to elicit augmented host responses to the immunogen vector. The particular cytokine encoded by the vector is not critical to the present invention includes, but not limited to, interleukin-4 (herein referred to as "IL- 4"), IL-5, IL-6, IL-10, IL-12 p40, IL-12 p70, TGFp and TNFa.

Vectors according to the invention can also comprise a promoter region, which can be used to regulate the transcription of the polynucleotide of the invention. Said promoter region can comprise a constitutive promoter, i.e., a promoter which directs the transcription in a basal manner, or an inducible promoter, in which the transcriptional activity requires an external signal. Suitable constitutive promoters for regulating the transcription are, among others, the CMV promoter, the SV40 promoter, the DHFR promoter, the mouse mammary tumor virus (MMTV) promoter, the elongation factor la (EFla) promoter, the albumin promoter, the ApoAl promoter, the keratin promoter, the CD3 promoter, the immunoglobulin heavy or light chain promoter, the neurofilament promoter, the neuron- specific enolase promoter, the L7 promoter, the CD2 promoter, the myosin light chain kinase promoter, the HOX gene promoter, the thymidine kinase promoter, the RNA Polymerase II promoter, the MyoD gene promoter, the phosphoglycerokinase (PGK) gene promoter, the low-density lipoprotein (LDL) promoter, the actin gene promoter. The inducible promoters which can be used in the context of the present invention are preferably those which respond to an inducing agent, which show nil or negligible basal expression in the absence of inducing agent and which are capable of promoting the activation of the gene located in the 3' position. Depending on the type of inducing agent, the inducible promoters are classified as Tet on/off promoters (Gossen, M. and H. Bujard (1992) Proc.Natl.Acad.Sci.USA, 89:5547- 5551; Gossen, M. et al, 1995, Science 268: 1766-1769; Rossi, F.M.V. and H.M. Blau, 1998, Curr. Opin. Biotechnol. 9:451-456); Pip on/off promoters (US6287813); antiprogestin-dependent promoters (US2004132086), ecdysone-dependent promoters (Christopherson et al, 1992, Proc.Natl.Acad.Sci.USA, 89:6314-6318; No et al, 1996, Proc.Natl.Acad.Sci.USA, 93:3346-3351, Suhr et al, 1998, Proc.Natl.Acad.Sci.USA, 95:7999-8004 and W09738117), a metallothionein-dependent promoter (WO8604920) and rapamycin-dependent promoters (Rivera et al., 1996, Nat.Med. 2: 1028-32).

Additionally, the vector can contain additional expression-regulating elements such as start and stop signals, cleavage sites, polyadenylation signal, origin of replication, transcriptional activators (enhancers), transcriptional silencers (silencers), etc. Generally, said elements are chosen depending on the host cells which are to be used.

The vector can additionally contain a transcription terminator sequence, such as the terminator of the bovine or human growth hormone gene, the terminator of the SV40 early genes, the terminators of the beta globin genes.

The polynucleotides and vectors according to the invention may be provided within host cells. Furthermore, the present invention also contemplates a host cell (host cell of the invention) comprising the first polynucleotide of the invention encoding a fusion protein comprising a structural protein from a virus of the Dicistroviridae family, particularly the Triatoma virus, and a heterologous polypeptide as described above as well as a host cell comprising the vector of the invention comprising said polynucleotide as described above.

According to the invention, the host cell can be a bacterium, wherein said bacterium can be a gram negative bacterial cell, this term intended to include all facultative anaerobic Gram-negative cells of the family Enterobacteriaceace such as Escherichia, Shigella, Citrobacter, Salmonella, Klebsiella, Enterobacter, Erwinia, Kluyvera, Serratia, Cedecea, Morganella, Hafhia, Edwardsiella, Providencia, Proteus and Yersinia. In another preferred embodiment, the bacterium is a gram positive bacterial cell of the genus Mycobacteriaceae such as M. bovis- CG, M. leprae, M. marinum, M. smegmatis and M. tuberculosis. In another embodiment, the host cell can be an insect cell including, without limitation, Sf9 cells, SF21 cells, SF+ cells, High- Five cells, or insect larval cells. In a particular embodiment, the host cell is an insect cell, more particularly a High Five (H5) (BTI-TN-5B1-4) insect cell, commercially available from, for example, Invitrogen.

The polynucleotide DNA of interest can be integrated or incorporated into the host cell genome and is referred to as integrated DNA or integrated DNA of interest. As a result, the DNA of interest can be introduced stably into and expressed in a host cell (i.e. production of foreign proteins is carried out from the DNA of interest present in the host cell). Alternatively, the DNA of interest is integrated into the host cell DNA, as a result of homologous recombination. A recombinant plasmid is used for introduction of the DNA of interest into the host cells and for stable integration of the DNA into the host cell genome. The recombinant plasmid used includes: 1) host cell sequences (referred to as plasmid-borne host cell sequences) necessary for homologous recombination to occur (between plasmid-borne mycobacterial sequences and sequences in the mycobacterial genome); 2) DNA sequences necessary for replication and selection; and 3) the DNA of interest (e.g. DNA encoding a selectable marker and DNA encoding a protein or polypeptide of interest). The recombinant plasmid is introduced, using known techniques, into the host cells. Therapeutic methods of the virus-like particle, first polynucleotide and vector of the invention

The VLPs of the invention are particularly useful in the generation of an immune response against the heterologous polypeptide comprised by said VLPs. Therefore, in another aspect, the present invention relates to a vaccine or immunogenic composition comprising a VLP of the invention as described above, the first polynucleotide of the invention as described above, or a vector of the invention as described above. The pharmaceutical compositions according to the present invention comprise vaccines and immunogenic compositions containing the VLP, first polynucleotide, or vector of the invention. In a particular embodiment, said pharmaceutical composition comprises a VLP according to the invention, wherein said VLP comprises a heterologous polypeptide in such a way that an immune response against said antigenic heterologous polypeptide is induced. In another particular embodiment, said pharmaceutical composition comprises a first polynucleotide according to the invention, wherein said polynucleotide encodes a fusion protein comprising a heterologous polypeptide in such a way that an immune response against said antigenic heterologous polypeptide is induced. In another particular embodiment, said pharmaceutical composition comprises a vector according to the invention, wherein said vector encodes a fusion protein comprising a heterologous polypeptide in such a way that an immune response against said antigenic heterologous polypeptide is induced.

Prior to administration to humans as a vaccine, the VLP, first polynucleotide or vector of the invention may be tested according to methods well-known in the art. For example, tests for several variables (e.g. toxicity, virulence, safety) are carried out in suitable animal models (e.g. mice, guinea pigs), some of which are usually immunocompromised. The ability of the vaccine preparations to elicit an immune response is tested likewise in suitable animal models (e.g. mice, non-human primates). In addition, protection studies involving vaccination, boosting and subsequent challenges are also carried out using suitable animal models (e.g. mice, guinea pigs, non- human primates), so that the contribution of the unspecific protection and immunity conferred by the vector can be depicted.

The amount of the VLP, first polynucleotide of vector of the present invention to be administered will vary depending on the species of the subject, as well as the disease or condition that is being treated. Preferably the subject is a mammal. More preferably, the subject is a human.

In another embodiment, the subject to which the VLP, first polynucleotide or vector, and pharmaceutical compositions thereof of the present invention are administered is a non-human mammal. In a preferred embodiment, the subject is a non- human primate, cow, goat, cat, dog, pig, buffalo, badger, possum, deer, or bison. In another aspect, the invention relates to a VLP as described above, to a first polynucleotide as described above, or to a vector of the invention as described above, for use in the treatment of an infectious disease caused by a pathogenic organism and/or an immune reaction caused by an allergen from which the heterologous peptide of the VLP is derived. Alternatively, the invention relates to a method for the treatment of an infectious disease caused by a pathogenic organism that comprises the administration to a subject in need thereof of the VLP of the invention comprising a heterologous polypeptide derived from said pathogenic organism, a first polynucleotide as described above, or a vector of the invention as described above. More alternatively, the invention relates to the use of the VLP of the invention, to a first polynucleotide as described above, or to a vector of the invention as described above, in the manufacture of a medicament for the treatment of an infectious disease caused by a pathogenic organism from which the heterologous peptide of the VLP is derived.

As it has been previously described in the context of the VLPs of the invention, said VLPs comprise a heterologous polypeptide, wherein said polypeptide is an epitope of a viral antigen, a bacterial antigen, a fungal antigen, an allergen or environmental antigen or a tumor antigen. Therefore, diseases that may be treated or prevented by using the VLPs and pharmaceutical compositions of the present invention include without limitation diseases involving viruses, bacteria, fungi or any other agent comprising said antigens and including as well, without limitation, diseases affecting non-human mammals such as bovine tuberculosis, porcine reproductive respiratory syndrome, coccidiosis, leptospirosis, infectious laryngotracheitis, and leishmaniasis.

In a particular embodiment, the heterologous polypeptide of the VLP of the invention is a trypanosoma immunogen, in which case the VLP of the invention and/or compositions thereof are used for the treatment of trypanosomiasis. In a particular embodiment, the heterologous polypeptide of the VLP of the invention is a Trypanosoma cruzi immunogen, in which case the VLP of the invention and/or compositions thereof are used for the treatment and/or prevention of Chagas disease.

In another particular embodiment, the heterologous polypeptide of the VLP of the invention is a plasmodium immunogen, in which case the VLP of the invention and/or compositions thereof are used for the treatment and/or prevention of malaria. Suitable plasmodium antigens which may be used in the present invention are sporozoite surface protein 2 (TRAP/SSP2), liver-stage antigen (LSA in particular LSA3), Pf exported protein 1 (Pf Expl)/Py hepatocyte erythrocyte protein (PyHEP17), and Pf antigen 2 (where Pf represents Plasmodium falciparum and Py represents Plamsodium yoelii), sporozoite and liver stage antigen (SALSA), sporozoite threonine and asparagines-rich (STARP), circumsporozoite protein (CSP), merozoite surface protein 1 (MSP2), in particular merozoite surface protein 1 (MSP-1), merozoite surface protein 2 (MSP-2) merozoite surface protein 3 (MSP-3), merozoite surface protein 4 (MSP-4), merozoite surface protein 6 (MSP-6), Ring-infected erythrocyte surface antigen (RES A), Rhoptry associated protein 1 (RAP-1), Apical membrane antigen 1 (AMA-1), erythrocyte binding antigen (EBA-175), erythrocyte membrane-associated giant protein or antigen 332 (Ag332), dnaK-type molecular chaperone, glutamate-rich protein (GLURP), in particular MSP3-GLURP fusion protein, erythrocyte membrane protein 1 (EMP-1), serine repeat antigen (SERA), clustered-asparagine-rich protein (CARP), cirumsporozoite protein-related antigen precursor (CRA), cytoadherence- linked asexual protein (CLAG), acid basic repeat antigen (ABRA) or 101 kDa malaria antigen, Rhoptry antigen protein (RAP-2), Knob-associated histidine-rich protein (KHRP), Rhoptry antigen protein (RAP), cysteine protease, hypothetical protein PFE1325w, protective antigen (MAg-1), fructose-bisphosphate aldolase, ribosomal phosphoprotein PO, P-type ATPase, glucose-regulated protein (GRP78), asparagine and aspartate-rich protein (AARPl), interspersed repeat antigen or PFE0070w. Antigens of the sexual stage which may be used in the present invention are Sexual stage and sporozoite surface antigen, antigen Pfg27/25, antigen QF122, 11-1 polypeptide, gametocyte-specific surface protein (Pfs230) ookinete surface protein (P25), chitinase, multidrug resistance protein (MRP). The antigens may derive from any of the five species of Plasmodium parasites known to infect human: Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, Plasmodium knowlesi and Plasmodium falciparum.

In another embodiment, the heterologous polypeptide of the VLP of the invention is a taenia immunogen, particularly an epitope from Taenia crassiceps (causing murine cysticercosis and that has been shown to protect pigs against T. solium cysticerosis) in which case the VLP of the invention and/or compositions thereof are used for the treatment of porcine cysticercosis. Suitable immunogens include, without limitation, KETcl, GK-1, and KETcl2, as described previously.

In another embodiment, the immunogen is a mycobacteria immunogen, in which case the recombinant mycobacteria is used for the treatment of a disease caused by the mycobacteria infection. Suitable mycobacteria immunogen include, without limitation, the 85A, 85B or 85C antigens from Mycobacterium tuberculosis or Mycobacterium bovis or a variant thereof.

Accordingly, the vaccines and compositions are administered in a manner compatible with the dosage formulation, and in such amount as will be therapeutically effective and immunogenic. The quantity to be administered depends on the subject to be treated, capacity of the subject's immune system to generate a cellular immune response, and degree of protection desired. Precise amounts of active ingredient required to be administered depend on the judgment of the practitioner and are peculiar to each individual. However, suitable dosage ranges are of the order of about one microgram to about one milligram, preferably about 1 microgram and more preferably about 5 micrograms, and more preferably 100 micrograms active ingredient per kilogram bodyweight individual. Suitable regimes for initial administration and booster shots are also variable, but are typified by an initial administration followed in one or two week intervals by a subsequent injection or other administration.

The vaccines of the invention may be specially formulated for administration in solid or liquid form, including those adapted for the following: (a) oral administration, such as drenches (aqueous or non-aqueous solutions or suspensions), tablets, boluses, powders, granules, pastes, mouthwash or hydrogels, (b) parenteral administration, for instance, by subcutaneous, intramuscular or intravenous injection of, for example, a sterile solution or suspension, (c) intracavity administration (e.g. intraperitoneal instillation), intravesical (i.e. urinary bladder) instillation, intrathecal administration, (d) intraorgan administration (e.g. intraprostatical administration), (e) topical application (i.e. cream, ointment or spray applied to the skin), (f) intravaginal or intrarectal administration (e.g. as a pessary, cream, foam, enema or suppository) or (g) aerosol (e.g. as an aqueous aerosol, liposomal preparation or solid particles containing the agent(s)). In vitro assays and animal studies can be used to determine an effective amount of the VLP, first polynucleotide or vector of the invention, or combinations thereof. A person of ordinary skill in the art would select an appropriate amount of each individual compound in the combination for use in the aforementioned assays or similar assays. Changes in cell activity or cell proliferation can be used to determine whether the selected amounts are an effective amount for the particular combination of compounds. The regimen of administration also can affect what constitutes an effective amount. Further, several divided dosages, as well as staggered dosages, can be administered daily or sequentially, or the dose can be proportionally increased or decreased as indicated by the exigencies of the therapeutic situation.

Process for producing a virus-like particle expressing a heterologous polypeptide of interest The TrV- VLP according to the present invention can be obtained by means of the expression of a nucleotide sequence encoding TrV structural proteins VP1, VP2 VP3, VP4, and/or VPO, or a nucleotide sequence encoding TrV structural protein precursor PI, and the nucleotide sequence encoding the fusion protein comprising the heterologous polypeptide of interest and at least one of said TrV structural proteins in suitable host cells. Therefore, the invention relates to a process for obtaining a VLP, comprising culturing a host cell containing a polynucleotide comprising the nucleotide sequence encoding the structural proteins and the nucleotide sequence encoding the heterologous protein of interest, under conditions allowing the expression of said polynucleotide.

Therefore, in another aspect, the present invention relates to a process for obtaining a Dicistroviridae family virus VLP modified to express a heterologous protein of interest, comprising the steps of:

(i) contacting a host cell with a first polynucleotide which encodes a fusion protein comprising a heterologous polypeptide of interest and the structural protein precursor (PI) of a virus of the Dicistroviridae family or a functionally equivalent variant thereof, and (ii) maintaining the cells under conditions suitable for the expression of the polynucleotide introduced in the cell in step (i).

TrV.

Thus, in a first step of the process of the invention for obtaining a modified VLP of a virus of the Dicistroviridae family, a host cell and a polynucleotide are contacted under conditions suitable for the entry of said polynucleotide into the cell, wherein said polynucleotide encodes a fusion protein comprising

(a) a heterologous polypeptide of interest, and

(b) the structural protein precursor (PI) of the virus of the Dicistroviridae family or a functionally equivalent variant thereof.

Suitable polynucleotides for use in the first step have been described in the context of the polynucleotides of the invention and are equally useful for the method for the generation of VLPs according to the present invention.

The conditions suitable for the entry of the polynucleotide in the host cell are well known for the person skilled in the art and include the microinjection of a composition comprising the polynucleotide or, alternatively, contacting the cell with a co-precipitate of the polynucleotide and calcium phosphate or calcium chloride or, alternatively, using transfection techniques such as DEAE-dextran, lipofection, electroporation as well as an entire series of transfection kits based on the previous techniques and which are commercially available. Alternatively, the polynucleotide can form part of a viral vector, in which case the conditions suitable for the entry of the polynucleotide in the cell include contacting the cell with said viral vector. Viral vectors suitable for the introduction of the polynucleotide in the cell include but are not limited to adenoviral vectors, adeno-associated vectors, retroviral vectors, lentiviral vectors, vectors based on herpes simplex or vectors based on alphaviruses. In a preferred embodiment of the invention, the polynucleotide is introduced into the cell using a vector, more preferably using a bacmid vector (baculovirus shuttle vector).

The polynucleotide encoding a fusion protein comprising a heterologous protein of interest and the structural protein precursor (PI) of the Triatoma virus or a functionally equivalent variant thereof may further comprise additional elements for expression of the heterologous protein in an adequate host cell. Therefore, in a particular embodiment, the polynucleotide comprises a promoter region to regulate the transcription of said polynucleotide. Said promoter is selected from a constitutive promoter and an inducible promoter, which have been previously described in the context of the first polynucleotide of the present invention. In a particular embodiment, the polynucleotide comprises a polyhedrin promoter. Additionally or alternatively, the polynucleotide comprises additional expression-regulating elements such as start and stop signals, cleavage sites, polyadenylation signal, origin of replication, transcriptional activators (enhancers), transcriptional silencers (silencers), transcription terminator sequences, etc. Generally, said elements are chosen depending on the host cells which are to be used

The efficiency of the transfection will depend on a series of factors including the type of cell, the number of passages, the state of confluence as well as the transfection conditions (time, form of preparation of the liposomes or of the precipitates, etc.). All these parameters can be determined and adjusted by means of routine experimentation.

In a particular embodiment, the step (i) of the method of the invention further comprises contacting the host cell used in said step (i) with one or more additional polynucleotides, under conditions suitable for the entry of said one or more additional polynucleotides into the cell, wherein said one or more additional polynucleotides comprise the nucleotide sequence encoding the non-structural (NS) protein precursor the Triatoma virus or a functionally equivalent variant thereof.

Suitable heterologous polypeptides have been described previously in the context of the TrV-VLP of the invention.

In a particular embodiment, the heterologous polypeptide comprises a first member of a binding pair. VLPs will thus be obtained in which the capsid will be modified by the presence of multiple copies of said ligand, which will allow the formation of conjugates between the VLPs and a compound of interest which is capable of binding specifically to said encoding sequence, such as a second member of a binding pair. This modification of the VLPs will allow addressing the particles to a target organ or cell of interest having on its surface molecules with the capacity to bind specifically to said heterologous sequence.

In a particular embodiment, said first member of a binding pair is selected from the group consisting of a peptide comprising the tripeptide Arg-Gly-Asp, a peptide comprising the sequence XBBXBX (SEQ ID NO:22), wherein X represents any aminoacid and B represents Arg or Lys, and a peptide comprising the sequence XBBBXXBX (SEQ ID NO:23), wherein X represents any aminoacid and B represents Arg or Lys and a biotin acceptor peptide (BAP).

In a particular embodiment, the heterologous polypeptide is an epitope. In an alternative more particular embodiment, the heterologous polypeptide is an epitope of a viral antigen, a bacterial antigen, a fungal antigen, an allergen or environmental antigen or a tumor antigen. Preferred epitopes according to the invention are selected from the group comprising PFR-2, PFR-3, RAP-2, RAP-3, KETcl, GK-1, KETcl2 and HSP-70. Particular preferred sequences for these epitopes have been described previously.

In another particular embodiment, the heterologous polypeptide is BAP. In a more particular embodiment, the heterologous polypeptide is biotinylated BAP.

According to the process of the invention, the nucleotide sequence encoding the heterologous polypeptide comprised by the fusion protein may be inserted in the nucleotide sequence encoding structural protein precursor PI of the Triatoma virus or functionally equivalent variant thereof at different positions. In a particular embodiment, said nucleotide sequence encoding the heterologous polypeptide is inserted at:

a nucleotide position corresponding to an amino acid inside at least one TrV structural protein derived from P 1 ,

a nucleotide position corresponding to the amino terminal end of at least one TrV structural protein derived from PI, and/or

a nucleotide position corresponding to the carboxy terminal end of at least one TrV structural protein derived from PI,

wherein said at least one TrV structural protein is the same TrV structural protein or is a different TrV structural protein, and/or wherein said heterologous polypeptide is the same polypeptide or is different polypeptide.

In a particular embodiment, the nucleotide sequence encoding the heterologous polypeptide is located between nucleotide positions which result in a fusion protein wherein the heterologous polypeptide is located at a position selected from the group consisting of:

between amino acid positions Ala681 and Trp688 in VP1 structural protein, between amino acid positions Asp841 and Thr854 in VP1 structural protein, after amino acid position Leu860 in VP1 structural protein,

between amino acid positions Thr97 and Lysl03in VP2 structural protein, after amino acid position Ala251 in VP2 structural protein,

- after amino acid positions Thr498 and Gln531 in VP3 structural protein, and/or after amino acid position Glu586 in VP3 structural protein.

Additionally, in a second step of the process of the invention for obtaining a modified VLP of a virus of the Dicistroviridae family, the host cell is maintained under conditions suitable for the expression of the polynucleotide introduced in said cell in the previously described step (i) of the process.

Conditions suitable for the expression of the polynucleotide in the host cell include those conditions that allow the optimal growth of said host cell and those conditions that allow the protein expression in said host cell. Said culture conditions are typically different for each type of host cell. However, those conditions are known by skilled workers and are readily determined. Similarly, the duration of maintenance can differ with the host cells and with the amount of VLP desired to be prepared. Again, those conditions are well known and can readily be determined in specific situations. Additionally, specific culture conditions can be obtained from the examples herein.

According to the method of the invention, the polynucleotide encoding a fusion protein comprising a heterologous polypeptide and a the structural protein precursor (PI) of the Triatoma virus or a functionally equivalent variant and the polynucleotide which comprises a sequence encoding the non-structural protein precursor (NS) of the Triatoma virus or a functionally equivalent variant thereof are provided in the same polynucleotide or in different polynucleotides.

Therefore, in a particular embodiment, the method of the invention comprises, in a first step, contacting a host cell with a polynucleotide under conditions suitable for the entry of said polynucleotide into the cell, wherein said polynucleotide encodes a fusion protein comprising

(a) a heterologous polypeptide of interest, and

(b) the structural protein precursor (PI) of the Triatoma virus or a functionally equivalent variant thereof, and wherein said polynucleotide further comprises a nucleotide sequence encoding the non-structural protein precursor (NS) of the Triatoma virus or a functionally equivalent variant thereof.

In an alternative embodiment, the method of the invention comprises, in a first step, contacting a host cell with polynucleotides under conditions suitable for the entry of said polynucleotides into the cell, wherein a first polynucleotide encodes a fusion protein comprising

(a) a heterologous polypeptide of interest, and

(b) the structural protein precursor (PI) of the Triatoma virus or a functionally equivalent variant thereof,

and wherein at least a second polynucleotide further comprises a nucleotide sequence encoding the non-structural protein precursor (NS) of the Triatoma virus or a functionally equivalent variant thereof.

In particular, sequences necessary for the generation of the VLPs by the process of the invention include the sequences encoding the structural capsid proteins (VP1, VP2, VP3 and VP4; or VP1 , VP2 and VPO). Therefore, it is possible to contact the cell used in step (i) with polynucleotides encoding each of said structural proteins. However, the person skilled in the art will understand that use can be made of the genomic organization itself of the Triatoma virus wherein all the proteins necessary for the formation of the capsids are synthesized in the form of a polyprotein comprising both the aforementioned structural capsid proteins and the non-structural capsid proteins (structural protein precursor PI and the non-structural NS protein precursor) but which are necessary for processing the polyprotein. In that case, the method of the invention would comprise contacting the cell with a polynucleotide comprising the sequence encoding said polyprotein.

The person skilled in the art will understand that the objective of steps (i) and (ii) of the process of the invention for obtaining a Triatoma virus VLP modified to express a heterologous protein of interest is to provide the cell with all the components necessary for the formation of said VLPs, therefore they can be carried out sequentially or simultaneously.

The process of the invention for obtaining a modified Triatoma virus VLP may further comprise a step which comprises recovering the VLPs from the cell culture used in the previous steps. The particles can be recovered from the cells or from the supernatant of the culture medium. In the first case, the step of recovering requires the separation of the cells from the culture medium by any method known by the persons skilled in the art (trypsinization and centrifugation or filtration) and the rupture of said cells in an inert solution (freezing/thawing cycles, homogenization, sonication, cavitation, use of detergents and the like). Subsequently, it is possible to recover the particles from the cell homogenate or from the supernatant of the culture medium using well known methods such as density gradient ultracentrifugation (for example, using CsCl or sucrose) as has been described by Lombardo et al. (J. Virol, 1999, 73:6973- 6983) and by Nick, H., et al. (J. Virol, 1976, 18:227-234), by means of affinity chromatography using anti-VP2 antibodies, by means of filtration using a series of fiberglass filters with a final pore size of 0.2 μιη, as has been described in US2005214316. A preferred method for recovery of the TrV VLPs of the invention is shown in Example 1.5 of the present application.

As previously described, the heterologous polypeptide of interest comprised by the fusion protein is a first member of a binding pair. Therefore, additionally or alternatively, the process of the invention for obtaining a modified Triatoma virus VLP may further comprise a step which comprises contacting the VLPs with a second member of a binding pair under conditions adequate for the interaction between said first and second members of the binding pair to occur. Conditions adequate for interaction such as the temperature, pH, adequate buffers, humidity, time for contact between the both members, binding pair components concentration, particle size, blocking solutions, washing steps, etc. may be adjusted as necessary by the skilled person to obtain an optimal product.

In a particular embodiment, the heterologous polypeptide comprised by the fusion protein is a first member of a binding pair, wherein said first member of a binding pair is biotinylated BAP, and the second member of the binding pair is a molecule comprising a biotin-binding region, wherein said molecule containing a biotin-binding region is selected from the group comprising avidin, an avidin analog, streptavidin, and streptavidin analog. The present invention relates as well to the VLPs obtained by a process for obtaining a VLP of a virus of the Dicistroviridae family, particularly TrV, modified to express a heterologous protein of interest as it has been described above.

The present invention relates as well to vaccine or immunogenic compositions comprising the VLPs as above, wherein said VLPs have been obtained by the process of the invention as previously described.

The present invention relates as well to the VLPs as above, wherein said VLPs have been obtained by the process of the invention as previously described, for use in the treatment of an infectious disease caused by a pathogenic organism and/or an immune reaction caused by an allergen from which the heterologous peptide of the VLP is derived. Alternatively, the invention relates to a method for the treatment of an infectious disease caused by a pathogenic organism and/or an immune reaction caused by an allergen that comprises the administration to a subject in need thereof of the VLP obtained by the process of the invention as previously described. More alternatively, the invention relates to the use of the VLP obtained by the process of the invention as previously described, in the manufacture of a medicament for the treatment of an infectious disease caused by a pathogenic organism and/or an immune reaction caused by an allergen from which the heterologous peptide of the VLP is derived. Second polynucleotide of the invention

(ii) the 5 ' UTR of the TrV virus genome,

(iv) the intergenic region of the genome of TrV virus,

(vi) the 3 ' UTR of the TrV virus genome and (vii) a second autocatalytic ribozyme capable of cleaving the sequence containing said ribozyme at the 5' end of the ribozyme.

Element (i)

Element (i) of the R A polynucleotide of the invention is an R A sequence encoding a first autocatalytic ribozyme capable of cleaving the sequence containing said ribozyme at the 3' end of the ribozyme. In a particular embodiment, the first autocatalytic ribozyme capable of cleaving the sequence containing said ribozyme at the 3' end of the ribozyme (element (i) of the RNA polynucleotide of the invention) is the hammerhead ribozyme (HamRz). In a particular embodiment, the hammerhead ribozyme comprises the sequence corresponding to GenBank accession number L35892.1 (125 nucleotides, NCBI database as of March 7^th, 2000).

Element (ii)

Element (ii) in the RNA polynucleotide of the invention is the 5' UTR of the TrV virus genome. In a preferred embodiment, the 5' UTR of the TrV virus genome comprises the RNA sequence as in region 1-548 of the sequence NC_003783.1. In another embodiment, the 5' -UTR is a functional equivalent variant thereof of the RNA sequence as in region 8716-9010 of the sequence NC 003783.1.

According to the invention, a functional equivalent variant of the untranslated region of the Triatoma virus genome, in particular of the 5' UTR, is understood as any sequence having additions, substitutions, deletions or combinations thereof in its nucleotide sequence and/or which has been chemically modified with respect to said sequence and which substantially maintains the function of the non-translated regulatory sequences, particularly the capacity to promote the replication of the sequences located in the 3' direction mediated by the RNA-dependent RNA polymerase, the capacity to promote the translation of the sequences located in the 3' direction and/or the capacity to promote the encapsidation of nucleic acids containing said regulatory sequences in the VLPs. Suitable assays for determining the capacity of a determined sequence to promote the transcription or the expression of sequences located in the 3' direction are, for example, the assay described by Nagarajan and Kibenge (J. Virol. Methods., 1998 72:51-58). Preferably, the variants of the non-translated 5' region of the Triatoma virus show said capacity to regulate the transcriptional expression of the nucleotide sequence operatively coupled in the 3 ' position at least by 60%, preferably by 70%, advantageously by 80%, more preferably by 90%>, more preferably by 95%, even more preferably by 97% and even more preferably by 98%, advantageously by 99%.

Element (Hi)

Element (iii) of the R A polynucleotide according to the invention is the sequence encoding the non-structural protein precursor NS of the Triatoma virus or a functionally equivalent variant thereof. In a particular embodiment, the sequence encoding the non-structural protein precursor NS of the Triatoma virus or a functionally equivalent variant thereof comprises the RNA sequence as in region 549-5936 of the sequence NC 003783.1 , or a functionally equivalent variant thereof.

In the context of the invention, "functionally equivalent variant" of a nonstructural protein precursor NS of the Triatoma virus is understood as any sequence having additions, substitutions, deletions or combinations thereof in its nucleotide sequence and/or which has been chemically modified with respect to said sequence and which substantially maintains the function of said non- structural protein precursor, particularly the capacity to separate strands of a DNA double helix or a self-annealed RNA molecule using the energy from ATP hydrolysis if the non- structural protein is an helicase, the proteolytic capacity if the non-structural protein is an peptidase, and/or the capacity to catalyze the synthesis of the RNA strand complementary to a given RNA template if the non-structural protein is an RNA-dependent RNA polymerase. Suitable assays for determining helicase activity are known in the art and include, without limitation, electrophoresis (Venkatesan M et al. 1982 J Biol Chem 257: 12426-34; Matson SW et al. 1983 J Biol Chem 258: 14017-24), measure of the sensitization of labeled duplex DNA to single-strand specific nucleases, such as SI or exonuclease I, resulting in the production of ssDNA during unwinding (Palas KM & Kushner SR 1990 J Biol Chem 265:3447-54) and electron microscophy (Runyon GT et al. 1990 Proc Natl Acad Sci. 87:6383-7). Suitable assays for determining peptidase activity are known by the skilled person and include without limitation, fluorescence resonance energy transfer (FRET) assays, spectrophotometric assays and fluorometric assays. Suitable assays for determining RNA-dependent RNA polymerase activity include, without limitation, radioactive assays and fluorometric assays, and are disclosed in, for example, Okazaki T et al. 1964 J Biol Chem 239:259-68; Johanson KO et al. 1980 J Biol Chem 255(22): 10984- 90; US 5635349; Seville M et al. 1996 Biotechniques 21(4): 664-672; and Ma C et al. 2006 Anal Biochem 353(1): 141-3. Preferably, the functional equivalent variants of the non-structural protein precursor NS of the Triatoma virus show the aforementioned helicase, peptidase and/or R A-dependent R A polymerase activities at least by 60%, preferably by 70%>, advantageously by 80%>, more preferably by 90%), more preferably by 95%, even more preferably by 97% and even more preferably by 98%, advantageously by 99%.

Element (iv)

Element (iv) of the RNA polynucleotide according to the invention is the intergenic region of the genome of TrV virus. In a particular embodiment, the intergenic region of the genome of the Triatoma virus comprises the RNA sequence as in region 5937-6108 of the sequence NC 003783.1. In another embodiment, element (iv) is a functionally equivalent variant of the region 5937-6108 of the sequence NC 003783.1.

In the context of the invention, "functionally equivalent variant" of an intergenic region of the Triatoma virus is understood as any sequence having additions, substitutions, deletions or combinations thereof in its nucleotide sequence and/or which has been chemically modified with respect to said sequence and which substantially maintains the function of said intergenic region, particularly the capacity to activate translation of the downstream sequences. Suitable assays for determining whether a given sequence can be seen as a functionally equivalent variant of the intergenic region of the TrV include, for instance, an assay as described in the examples of the present application, wherein a RNA polynucleotide having the above elements is introduced into a cell, determining whether the sequence downstream of the intergenic region is expressed by detecting the protein encoded by said sequence.

Preferably, the functional equivalent variants of intergenic region of the

Triatoma virus show the aforementioned translation promoting activity of at least 60%, preferably 70%, advantageously 80%, more preferably 90%, more preferably 95%, even more preferably by 97% and even more preferably 98%, advantageously 99% of the translation promoting activity of the native intergenic region.

Element (v)

Element (v) of the RNA polynucleotide according to the invention is a sequence encoding the structural protein precursor PI of the Triatoma virus or a functionally equivalent variant thereof. In a preferred embodiment, element (v) comprises the R A sequence as in region 6109-8715 of the sequence NC 003783.1, or a functionally equivalent variant thereof.

In the context of the invention, "functionally equivalent variant" of structural protein precursor PI of the Triatoma virus is understood as any sequence having additions, substitutions, deletions or combinations thereof in its nucleotide sequence and/or which has been chemically modified with respect to said sequence and which substantially maintains the function of said structural protein precursor, particularly the capacity of giving raise to structural proteins able to assemble into a viral capsid and/or allow encapsidation of said structural proteins. Suitable assays for determining viral capsid assembly capacity are known by the skilled person and include electron microscopy, criomicroscopy, etc. as disclosed for example in Bottcher B et al. 1998 EMBO J 17(23):6839-45; and Yadav SS et al. 2012 Virology 429(2): 155-162. Preferably, the functional equivalent variants of the structural protein precursor PI of the Triatoma virus show the aforementioned viral capsid assembly activity at least by 60%, preferably by 70%, advantageously by 80%>, more preferably by 90%>, more preferably by 95%, even more preferably by 97% and even more preferably by 98%, advantageously by 99%.

Element (vi)

Element (vi) in the RNA polynucleotide of the invention is the 3' UTR of the

TrV virus genome. In a preferred embodiment, the 3' UTR of the TrV virus genome comprises the RNA sequence as in region 8716-9010 of the sequence NC 003783.1. In another embodiment, the 5' -UTR is a functional equivalent variant thereof of the RNA sequence as in region 8716-9010 of the sequence NC 003783.1.

According to the invention, a functional equivalent variant of the untranslated region of the Triatoma virus genome, in particular of the 3' UTR, is understood as any sequence having additions, substitutions, deletions or combinations thereof in its nucleotide sequence and/or which has been chemically modified with respect to said sequence and which substantially maintains the function of the non-translated regulatory sequences, particularly polyadenylation, translation efficiency, localization, and stability of the mRNA. Preferably, the variants of the non-translated 3' region of the Triatoma virus show said capacity of polyadenylation, translation efficiency, localization, and stability of the mR A of the nucleotide sequence operatively coupled at least by 60%, preferably by 70%, advantageously by 80%>, more preferably by 90%>, more preferably by 95%, even more preferably by 97% and even more preferably by 98%, advantageously by 99%.

Element (vii)

The R A polynucleotide of the invention comprises as well an R A sequence encoding a second autocatalytic ribozyme capable of cleaving the sequence containing said ribozyme at the 5 ' end of the ribozyme element (vii) of the RNA polynucleotide of the invention). In a particular embodiment, the second autocatalytic ribozyme capable of cleaving the sequence containing said ribozyme at the 5' end of the ribozyme (is the hepatitis delta virus ribozyme (HDVRz).

The hepatitis δ virus ribozyme (HDVRz) is capable of being self-processed such that, once the polynucleotide of the invention has been transcribed, the hepatitis δ virus ribozyme acts on the RNA strand, causing its elimination from the RNA strand. It is thus possible to exactly control the sequence of the terminal 3' region, length of the RNA molecule, since it is enough to include the sequence encoding the hepatitis δ virus ribozyme immediately in the 3 ' position with respect to the nucleotide which is to form the terminal nucleotide of the RNA molecule. In a particular embodiment, the HDVRz comprises the sequence corresponding to positions 1-88 as in the sequence located in GenBank under accession number AY261457 (NCBI database as of March 1^st, 2004).

The RNA polynucleotide according to the invention can be single stranded RNA (ssRNA), or double stranded RNA (dsRNA). Although RNAs can be introduced inside a cell both in vitro and in vivo using the suitable technology, the high sensitivity thereof to RNAses makes it preferable to administer a polynucleotide in the form of DNA. Thus, in another aspect, the invention relates to a DNA polynucleotide comprising at least one strand which is complementary to the RNA polynucleotide of the invention as described above. The DNA polynucleotide of the invention can be single stranded DNA (ssDNA), or double stranded DNA (dsDNA). In a particular preferred embodiment, the DNA polynucleotide of the invention further comprises a transcriptional regulatory region which regulates the expression of said DNA polynucleotide. Therefore, the DNA polynucleotide of the invention comprises at least one strand which is complementary to the RNA sequence encoding the first polynucleotide of the invention.

In the context of the present invention, a "sequence complementary to a determined sequence" is understood as the reverse of a sequence resulting from replacing each nucleotide in said determined sequence by the complementary nucleotide according to the rules established by Watson-Crick. Therefore, two sequences are complementary when they can be bound to one another in an antiparallel direction (the 5' end of one of them with the 3' end of the other one and each A, T(U), G and C of a sequence is paired, respectively, with a T(U), A, C and G. The reverse sequence is understood to mean a nucleic acid sequence in which the order of nucleotides is reversed as compared to the original sequence. For example, reverse sequence to AAGAG is GAGAA. The term "coding strand", as used herein, refers to the DNA strand which is complementary to the template strand. Such coding strand has the same base sequence as the mRNA (although with thymine replaced by uracil) and corresponds to the codons that are translated into protein. The term "template strand", as used herein, refers to the DNA strand that is used as a template for the synthesis of mRNA. Such template strand has a complementary sequence to the mRNA sequence. By "hybridize" is meant pair to form a double-stranded molecule between complementary polynucleotide sequences, or portions thereof.

The conditions under which completely complementary nucleic acid strands hybridize are referred to as "very severe hybridization conditions" or "sequence-specific hybridization conditions". Nevertheless, substantially complementary stable nucleic acid double strands can be obtained under less severe hybridization conditions, generically referred to as "severe hybridization conditions", in which case the tolerated degree of mismatch can be adjusted by means of the suitable adjustment of the hybridization conditions. The person skilled in the art can empirically determine the stability of a duplex by taking into account various variables, such as the length and concentration of base pairs of the probes, the ionic strength and the incidence of the mismatched base pairs, following the guidelines of the state of the art (see, for example, Sambrook et al, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, N. Y. (1989); and Wetmur, Critical Reviews in Biochem. and Mol. Biol. 26 (3/4):227-259 (1991)). By way of illustration, in a particular embodiment, the severe hybridization conditions comprise, for example, a concentration comprised between 0.15 M and 0.9 M of NaCl and a temperature comprised between 20°C and 65°C. In another particular embodiment, the very severe hybridization conditions comprise, for example, a concentration comprised between 0.02 M and 0.15 M of NaCl and a temperature comprised between 50°C and 70°C.

Thus, the DNA polynucleotide of the present invention can be a single stranded DNA (ssDNA), wherein said strand is complementary to the sequence of the RNA polynucleotide as described above, and therefore would have the previously indicated sequence of the Triatoma virus RNA genome read in the reverse direction (3' to 5') and replacing each U, A, C and G of said genome with A, T, G and C, respectively. Thus, when this DNA is copied by an RNA polymerase, the latter inserts in each position the base complementary to that which appears in the template, an RNA molecule is generated the sequence of which coincides with that of the Triatoma virus RNA genome, flanked by the sequences encoding the autocatalytic ribozymes

In another embodiment, the DNA polynucleotide of the present invention is double stranded DNA (dsDNA), wherein said DNA polynucleotide comprises a first strand as above (which is complementary to the sequence of the RNA polynucleotide as above) and a second strand complementary to said first strand.

The second DNA polynucleotide of the invention is under the operative control of a transcription regulatory region, wherein said transcription regulatory region regulates the expression of said DNA polynucleotide. In a particular embodiment, said transcription regulatory region comprises a promoter region.

In a particular embodiment, the DNA polynucleotide of the invention is operatively coupled to the transcription regulatory region. The term "operatively coupled" relates to an ordering of elements wherein each of said elements is arranged such that it performs its usual function. Thus, a gene is operatively coupled to a determined promoter when the promoter is capable of activating the transcription of said gene in the presence of the suitable enzymes. The promoter does not have to be contiguous to the sequence of the gene provided that it maintains the transcription- activating function. Thus, even when non-translated transduction regulatory sequences appear between the promoter and the end of the encoding sequence of the gene, the gene will be considered to be under operative control if its transcription is activated by said promoter.

The promoters which can be used to regulate the transcription of the DNA polynucleotide of the invention can be constitutive promoters, i.e., promoters which direct the transcription in a basal manner or inducible promoters in which the transcriptional activity requires an external signal. Suitable constitutive promoters for regulating the transcription are, among others, the CMV promoter, the SV40 promoter, the DHFR promoter, the mouse mammary tumor virus (MMTV) promoter, the elongation factor la (EFla) promoter, the albumin promoter, the ApoAl promoter, the keratin promoter, the CD3 promoter, the immunoglobulin heavy or light chain promoter, the neurofilament promoter, the neuron- specific enolase promoter, the L7 promoter, the CD2 promoter, the myosin light chain kinase promoter, the HOX gene promoter, the thymidine kinase promoter, the RNA Polymerase II promoter, the MyoD gene promoter, the phosphoglycerokinase (PGK) gene promoter, the low-density lipoprotein (LDL) promoter, the actin gene promoter.

The inducible promoters which can be used in the context of the present invention are preferably those which respond to an inducing agent, which show nil or negligible basal expression in the absence of inducing agent and which are capable of promoting the activation of the gene located in the 3' position. Depending on the type of inducing agent, the inducible promoters are classified as Tet on/off promoters (Gossen, M. and H. Bujard (1992) Pioc.Natl.Acad.Sci.USA, 89:5547-5551; Gossen, M. et al, 1995, Science 268: 1766-1769; Rossi, F.M.V. and H.M. Blau, 1998, Curr. Opin. Biotechnol. 9:451-456); Pip on/off promoters (US6287813); antiprogestin-dependent promoters (US2004132086), ecdysone-dependent promoters (Christopherson et al, 1992, Pioc.Natl.Acad.Sci.USA, 89:6314-6318; No et al, 1996, Proc.Natl.Acad.Sci.USA, 93:3346-3351, Suhr et al, 1998, Proc.Natl.Acad.Sci.USA, 95:7999-8004 and W09738117), a metallothionein-dependent promoter (WO8604920) and rapamycindependent promoters (Rivera et al, 1996, Nat.Med. 2: 1028-32).

In a particular preferred embodiment, the promoter is the polyhedrin promoter. In another embodiment, the second DNA polynucleotide of the invention can contain additional expression-regulating elements such as start and stop signals, cleavage sites, polyadenylation signal, origin of replication, transcriptional activators (enhancers), transcriptional silencers (silencers), transcription terminator sequences, etc. Generally, said elements, are chosen depending on the host cells which are to be used.

In a particular embodiment, the sequence encoding the structural protein precursor PI of the Triatoma virus or the functionally equivalent variant thereof further comprises a polynucleotide sequence encoding a heterologous polypeptide which results in a fusion protein comprising at least one of the structural proteins of the Triatoma virus and the heterologous polypeptide. More particularly, the polynucleotide sequence encoding the heterologous polypeptide is located within the sequence of the sequence encoding the structural protein precursor PI of the Triatoma virus so that, after expression, the heterologous polypeptide is located at a position selected from the group consisting of

- between amino acid positions Thr97 and Lysl03in VP2 structural protein, after amino acid position Ala251 in VP2 structural protein,

after amino acid positions Thr498 and Gln531 in VP3 structural protein, and/or

after amino acid position Glu586 in VP3 structural protein.

Heterologous polypeptides according to the invention have been described previously in the context of the TrV-VLP of the invention.

In a particular embodiment, the heterologous polypeptide comprises a first member of a binding pair. In a particular embodiment, the first member of a binding pair is selected from the group consisting of a polypeptide comprising the tripeptide Arg-Gly-Asp, a peptide comprising the sequence XBBXBX (SEQ ID NO:22), wherein X represents any aminoacid and B represents Arg or Lys, and a peptide comprising the sequence XBBBXXBX (SEQ ID NO:23), wherein X represents any aminoacid and B represents Arg or Lys, and a biotin acceptor peptide (BAP).

In another particular embodiment, the heterologous polypeptide comprises at least one epitope of an antigenic polypeptide. Epitopes according to the invention have been previously described and include epitopes comprised by a viral antigen, a bacterial antigen, a fungal antigen, an environmental antigen and a tumor antigen. Preferably, the antigens are selected from the group comprising PFR-2, PFR-3, RAP-2, RAP-3, KETcl, GK-1, KETcl2, and HSP-70.

In a particular embodiment, the polynucleotide sequence encoding the structural protein precursor PI of the Triatoma virus or the functionally equivalent variant thereof further comprises a polynucleotide sequence encoding a heterologous polypeptide which results in a fusion protein comprising at least one of the structural proteins of the Triatoma virus and the heterologous polypeptide. In a more particular embodiment, the polynucleotide sequence encoding the heterologous polypeptide is located within the sequence of the sequence encoding the structural protein precursor PI of the Triatoma virus so that, after expression, the heterologous polypeptide is located at a position selected from the group consisting of

after amino acid positions Thr498 and Gln531 in VP3 structural protein, and/or

after amino acid position Glu586 in VP3 structural protein.

Process for obtaining recombinant infectious TrV virions

The present invention also contemplates a process for obtaining an infectious Triatoma virus (TrV) based on the second polynucleotide of the invention as described above. Therefore, the present invention relates to a process for obtaining an infectious Triatoma virus (TrV), wherein said process comprises the following steps:

(i) contacting a host cell with the second polynucleotide of the invention under conditions suitable for the entry of said second polynucleotide into the cell, and

Conditions suitable for the entry of this second polynucleotide of the invention into a host cell have been described previously in the context of the process for producing a VLP expressing a heterologous polypeptide of interest. Suitable host cells have been described as well. In a particular embodiment, the host cell is an insect cell, preferably a High Five insect cell.

In a preferred embodiment, step (i) further comprises contacting the host cell with a polynucleotide encoding the NS non-structural protein precursor. This will allow increasing the intracellular concentration of the proteins needed for the replication of the viral genome and for the processing of the PI precursor protein.

In a second step, the host cells are maintained under conditions suitable for the expression of the polynucleotide previously introduced.

Conditions suitable for the expression of said polynucleotide introduced in said host cell have been described previously in the context of the process for producing a VLP expressing a heterologous polypeptide of interest.

In a particular embodiment, the infectious TrV particles are recovered. Methods for recovery of viral particles include those methods for the recovery of VLPs explained above, included the method described in Agirre et al. (supra).

The invention relates as well to those infectious TrV particles which are obtained by this method.

Use of recombinant infectious TrV virions of the invention as insecticide

The invention relates as well to a method for killing insects comprising the administration of an infectious Triatoma virus (TrV) obtained by a process as described previously.

In a particular embodiment, the insects susceptible of being killed by the method of the invention are hematophagous insects, preferably hematophagous insects which are vectors of diseases, more preferably which are vectors of human diseases.

In a particular embodiment, the insects susceptible of being killed by the method of the invention are insects which are susceptible of being infected by an infectious TrV virion obtained by the process of the invention for obtaining recombinant infectious TrV virions. In a particular preferred embodiment, said insect is an hematophagous insect, more particularly an hematophagous insect member of the Triatominae family, preferably a triatome insect, which is a vector of the Chagas disease. In an alternative embodiment, the hematophagous insect susceptible of being killed by the method of the invention is an insect of the Cimicidae family, preferably from Cimex genus, more preferably Cimex lectularius. The following examples illustrate the invention and must not be considered as limiting the scope thereof.

Example 1. Vaccine design based of TrV-VLPs

1.1. Candidate peptide epitopes from T. cruzi

Paraflagellar rod proteins (PFRs), located at the Tripanosoma cruzi flagellum and specific to the kinetoplastids, have been reported as vaccine candidates. PFR-2 and PFR-3 proteins are expressed in the three forms of the parasite. The CD8+ T cells immune response against specific antigens have shown to efficiently control the spread of T. cruzi in murine experimental infection.

Six human leukocyte antigen-A (HLA-A)*02:01-restricted epitopes, which are efficiently processed and presented in the context of the natural infection of T. cruzi, have been identified in the PFR-2 and PFR-3 from T. cruzi. These proteins contain at least six cytotoxic CD8+ T cell epitopes restricted to the HLA-A*02:01 molecule, named PFR219-28, PFR2156-163, PFR2449-457, PFR3428-436, PFR3475-482 and PFR3481-489, which are processed and presented during the natural infection of Chagas disease.

The amino acid sequences of these peptides are (from N-terminal to C-terminal):

1) PFR219-28: AVPEVTDVTL (SEQ ID NO:01)

2) PFR2156-163: KLEKIEDEL (SEQ ID NO:02)

3) PFR2449-457: RLYKTLGQL (SEQ ID NO:03)

4) PFR3428-436: FVSCCGELTV (SEQ ID NO:04)

6) PFR3475-482: DIIEQMKGV (SEQ ID NO:05)

7) PFR3481-489: GVSGVINAL (SEQ ID NO:06)

1.2. Candidate peptide epitopes from Plasmodium falciparum

Several studies have demonstrated the importance of responses mediated by antibodies to rhoptry-associated proteins (RAPs) in protection against malaria. In vitro studies showed that monoclonal antibodies directed against RAP-2 provide substantial inhibition of merozoites in invasion of red blood cells (RBCs). Experimental evidence demonstrated that RAP-2 is a ligand used by merozoites to invade RBCs. This protein has four RBC binding sequences defined by high-activity binding peptides (HABPs) numbered as 26220, 26225, 26229, and 26235 (3). Also, RAP-3 shows two HABPs, and these peptides are named 33860 and 33873.

The amino acid sequences of peptides HABPs are (from N-terminal to C- terminal):

1) RAP-2 HABP 26220: NHF S S ADELIKYLEKTNINT (SEQ ID NO:07)

2) RAP-2 HABP 26225: IKK PFLRVLNKASTTTHAT (SEQ ID NO:08)

3) RAP-2 HABP 26235: FLAEDFVELFDVTMDCYSRQ (SEQ ID NO: 09)

4) RAP-2 HABP 26229: RSVNNVISKNKTLGLRKRSS (SEQ ID NO: 10)

5) RAP-3 HABP 33860: FNHF SN VDE AIE YLKGLNIN (SEQ ID NO: l 1)

6) RAP-3 HABP 33873: KNRTYALPKVKGFRFLKQLF (SEQ ID NO: 12)

1.3. General strategy

The inventors have developed many recombinant TrV mutants carrying selected T. cruzi and P. falciparum epitopes. These epitopes are exposed to the solvent at the external TrV capsid surface. This is done either by inserting one of more peptides on the VP 1-4 structural proteins or by substitution these amino acid portion in the wt TrV sequence (GenBank AF 178440). Depending of the number of insertions, these VLPs will have a minimum of 60 copies of a single epitope, 120 copies by inserting 2 epitopes, and so on.

Regions for the insertion/substitution of the exogenous epitopes are:

- In protein VP 1 :

1) From Ala83 to Trp91 : Stretch of 9 amino acid long located between two structural β- strands (Pro79-Tyr82).

2) From Asp244 to Thr257: Stretch of 19 amino acids long located between two structural a-helixes (Ala239-Arg243, and Phe258 and Leu263).

3) From Leu263: Stretch at the protein C-terminal end (aa chain is unstructured from Ser264). This region is preceded by an a-helix (Thr257-Tyr262).

- In protein VP2:

1) From Thr97 to Lysl04: Stretch between two structural β-strands (Phe89-Asn96, and Glul05). 2) From Ala251 : C-terminal region pointing to the capsid exterior and after a structural β-strand (Ala230-Leu245).

- In protein VP3 :

1) From Thrl86 to Gln220: Stretch between two structural β-strands (Thrl74-Vall80, and Gly223-Ala229).

2) From Glu274: C-terminal region located after a structural β-strand (Ser271-Glu274), and aa chain with unknown structure after Pro276.

- In protein VP4: in any region of its sequence

1.4. Generation of transfer plasmids and recombinant baculoviruses

Production of Triatoma virus-Virus Like Particles (TrV-VLPs) was carried out by expressing the structural protein precursor PI and the non-structural protein precursor NS. Gene fragments encoding PI (nucleotides 6,109 to 8,715 from TrV full- length RNA; NCBI reference sequence: NC_003783) were obtained by RT-PCR using the following primers: 5 -CCGGAATTCATGCTCGCTGTAAATAATGTAAATATG- 3' (SEQ ID NO: 13) and 5 ^'-

ATAAGAATGCGGCCGCC7MAGTAGTGGACTCTGAAGTCG-3' (SEQ ID NO: 14). These primers incorporated EcoRI, and Notl restriction sites (underlined), respectively, ATG initiation codon (bold) and CTA stop codon (italic). Gene fragment encoding NS (nucleotides 549 to 5,933 from TrV full-length RNA; NCBI reference sequence: NC 003783) was also obtained by RT-PCR using the following primers: 5 ^'- AT AAGAATGCGGCCGC ATGGAATTTTTGCGAAAATTCTTAATTCC-3 ' (SEQ ID NO: 15) and 5 -CCGCTCGAGrC4CATAGTCAAGTCCGTAGG-3 ' (SEQ ID NO: 16). These primers incorporated Notl and Xhol restriction sites (underlined), respectively, ATG initiation codon (bold) and CTA stop codon (italic). The PCR products were treated with the corresponding restriction enzymes and cloned under the polyhedrin promoter into different pFastBacl plasmids (Invitrogen). Two recombinant plasmids were obtained: pFastBacl-Pl and pFastBacl-NS.

Recombinant plasmids were transformed into DHlOBac Escherichia coli strain (Invitrogen), in which sequences between Tn7R and Tn7L from the recombinant plasmids were site-specific transposed to the bacmids. These recombinant bacmids (Pl- bacmid and NS-bacmid) were isolated, screened by PCR and used for transfection of High Five (H5) insect cells (Invitrogen). Transfection was carried out by adding the transfection mixture (recombinant bacmid, lipofectamine 2,000 (Invitrogen) and TC- 100 insect medium (Invitrogen)) to a 60% confluent monolayer of H5 cells. Cells were incubated at 28°C for 4 hours and then transfection mixture was replaced by TC-100 medium supplemented with 5% (v/v) fetal crown serum (FCS). Cells were incubated at 28°C for 96 hours and recombinant baculoviruses were harvested by centrifugation and stored at 4°C.

1.5. Expression and purification of TrV-VLPs by co-infection with PI and NS TrV-VLPs were produced by co-infecting 90%> confluent monolayer of H5 cells cultured in TC-100 medium supplemented with 2% (v/v) FCS at 28°C with both PI and NS recombinant baculoviruses at a Multiplicity Of Infection (MOI) of 1 in both cases.

At 48h post-infection, cells were harvested by centrifugation and resuspended in lysis buffer (50mM Tris-HCl pH 7, 500mM NaCl, ImM MgCl₂ and 0.25% (v/v) Igepal CA-630 (Sigma-Aldrich)) supplemented with a Protease Inhibitor Cocktail tablet (Roche). Cells were lysed by incubation in lysis buffer for 20 min and by applying 3 freeze-thaw cycles. The cell lysate was centrifuged at 15,000g for 20 min to pellet cell debris and supernatant was centrifuged through a 20%> (w/v) sucrose cushion in water at 100,000g for 4h. The white pellet was resuspended in lmL of NMT buffer (50mM Tris- HCl pH 7, lOmM NaCl and ImM MgCl₂) and then loaded on the top of a 35mL discontinuous 10-30%) (w/v) sucrose gradient. The centrifugation was carried out at 100,000g for 2h and 30mins.

TrV-VLPs are shown in Figure 1.

1.6. Expression and purification of TrV-VLPs by infection only with PI

TrV-VLPs were also produced by infecting 90% confluent monolayer of H5 cells cultured in TC-100 medium supplemented with 2% (v/v) FCS at 28°C with PI recombinant baculo virus at a Multiplicity of Infection (MOI) of 1. Purification was carried out as described above. TrV-VLPs are shown in Figure 2.

Example 2. Generation of a reverse genetics system to rescue and production of infectious TrV

Expression of the two TrV ORFs, namely NS and PI, using recombinant baculoviruses results in the production of the full protein repertoire expected from the processing of both ORF-encoded polyproteins. Furthermore, the inventors have shown that coexpression of the NS and PI ORFs leads to the assembly of TrV VLP undistinguishable from purified TrV infectious particles when observed under EM. These results strongly support the feasibility of using a recombinant baculovirus (rBV)- based system to produce infectious TrV. To assess this possibility, a recombinant version of the full length TrV genome (NCBI Reference Sequence: NC 003783.1) flanked by the hammerhead ribozyme (HamRz) and the hepatitis delta virus ribozyme (HDVRz) at its 5' and 3' ends, respectively. This construct is synthesized in vitro and cloned into the pFastBac plasmid (Invitrogen) under the control of the BV polyhedrin promoter. The presence of the HamRz and HDVRz elements flanking the TrV genomic sequences is designed to ensure the correct trimming, carried out by the mentioned ribozymes, of the RNAs generated by transcription of the described construct during baculovirus replication to release RNAs with 5 ' and 3 ' identical to those found in the TrV genome. The resulting plasmid (named pFB HmRz-TrV-HDVRz) is used to generate a recombinant baculovirus, BV HmRz-TrV-HDVRz, harboring the described TrV construct by following the Bac-to-Bac protocol (Invitrogen; http://tools.invitrogen.com/content/sfs/manuals/bactobac_man.pdf). The BV HmRz- TrV-HDVRz virus is grown and titrated in HighFive cells using the Bac-to-Bac protocols (Invitrogen).

The BV HmRz-TrV-HDVRz virus is used to infect HighFive cells. At different times post-infection, cells are collected and used to generate the or to assess the presence of: i) TrV RNAs of the expected size by Northern blot analysis using TrV- specific 32P-labeled probes; ii) TrV polypeptides by Western blot analysis using specific antibodies against structural TrV polypeptides; and iii) TrV.

In parallel, a similar set of experiments are carried out to determine whether the overexpression of the TrV NS might improve the efficiency of the rescue protocol. For this, HighFive cells are simultaneously infected with BV HmRz-TrV-HDVRz and with the previously described rBV expressing the TrV ORFl . The expression of TrV RNA, structural proteins, virus particles and infective virus in extracts from coinfected are tested as described above.

Example 3. Immuno- stimulatory properties of TrV VLPs Spleen cells were obtained from female Mus musculus CD1 mice between 5 and 8 weeks of age, without any previous stimulation. 1 x 10⁶ cells were cultured in vitro in RPMI medium, supplemented with 10% of calf fetal serum at 37 °C and with 5 % C0₂.

The following conditions were used to stimulate the cells: Group 1 : PBS; Group 2: NMT buffer; Group 3: 1 μg lipopolysaccharide (LPS) from Escherichia coli; Group 4 : 1 μg of TrV VLPs; Group 5: 1 μg of empty TrV, and Group 6: 1 μg of TrV.

48 hours after stimulation, the levels of IFN- D produced by the cells were analyzed. An ELISA system was used to quantify IFN- D levels (mouse IFN-γ DuoSet ELISA Development System, R&D Systems). Results are shown in Figure 3.

These experiments clearly showed that the VLPs of TrV can elicit a cellular immune response as evaluated in a mice model.

Example 4. Accessibility of reactive groups on the TrV VLPs external surface

In order to evaluate the existence of reactive groups on the outer capsid surface of natural empty particles of TrV (n-VLPs), a commercial dye was conjugated to the

NH2⁺ group of the lysine side-chain. The dye used was Fluorescein (FL).

The experimental conditions were the following:

solutions containing Fluorescein (FL) at different concentrations.

Reactions were quenched by adding 0.1 mL of 1.5 M hydroxyl amine hydrochloride.

n-VLPs + FL samples were purified by size exclusion (Sephadex G25) using PBS buffer at pH 7.2. Fluorescence emission spectra of the samples were registered (Figure 4), showing that emission increases as the dye concentration is rised. No fluorescence was observed in the control sample.

These experiments showed that the TrV VLPs can be decorated with molecules able to react to NH2⁺ groups.

Claims

1. A virus-like particle (VLP) comprising

(i) the viral structural proteins VP1, VP2, VP3 and VP4 of a virus of the Dicistroviridae family, or the viral structural proteins VP1, VP2, and VPO of a virus of the Dicistroviridae family, or the structural protein precursor (PI) from a virus of the Dicistroviridae family, or a functionally equivalent variant any thereof, and

(ii) a heterologous polypeptide,

2. The VLP according to claim 1, wherein the virus of the Dicistroviridae family is the Triatoma virus (TrV).

3. The VLP according to any of claims 1 or 2, wherein the heterologous polypeptide comprises at least one epitope from an antigen selected from the group consisting of a viral antigen, a bacterial antigen, a fungal antigen, an environmental antigen or a tumor antigen.

4. The VLP according to claim 3, wherein the epitope is selected from the group comprising PFR-2, PFR-3, RAP-2, RAP-3, KETcl, GK-1, KETcl2, HSP-70.

5. The VLP according to claim 3, wherein the heterologous polypeptide comprises a first member of a binding pair.

6. The VLP according to claim 5, wherein the first member of a binding pair is selected from the group consisting of a biotin acceptor peptide (BAP), a peptide comprising the tripeptide Arg-Gly-Asp, a peptide comprising the sequence XBBXBX (SEQ ID NO:22), wherein X represents any amino acid and B represents Arg or Lys, and a peptide comprising the sequence XBBBXXBX (SEQ ID NO:23), wherein X represents any amino acid and B represents Arg or Lys.

7. The VLP according to any of claims 5 or 6, wherein the VLP is bound to a second member of a binding pair, said second member being bound to the VLP by interaction with the first member of the binding pair.

8. The VLP according to claim 7, wherein the first member of the binding pair is the biotinylated BAP and the second member of the binding pair is a molecule comprising a biotin-binding region.

9. The VLP according to claim 8, wherein the molecule comprising a biotin-binding region is selected from the group comprising avidin, an avidin analog, streptavidin, and streptavidin analog.

10. The VLP according to any of claims 1 to 9, wherein the heterologous polypeptide is inserted inside the amino acid sequence of at least one TrV structural protein, is bound to the amino terminal end of at least one TrV structural protein and/or is bound to the carboxy terminal end of at least one TrV structural protein wherein said at least one TrV structural protein is the same TrV structural protein or is a different TrV protein.

11. The VLP according to claim 10, wherein the heterologous polypeptide is located in VP1 structural protein, replacing the VP1 region from Ala681 to Trp688, replacing the VP1 region from Asp841 to Thr854 and/or by after Leu860 in VP1 protein,

in VP2 structural protein, replacing the VP2 region from Thr97 to Lysl03, and/or after Ala251 in VP2 protein, and/or

in VP3 structural protein, replacing the VP3 region from Thr498 to Gln531, and/or after Glu586 in VP3 protein, and/or

in VP4 structural protein, in any region of its aminoacid sequence.

12. The VLP according to any of claims 1 to 11, wherein said VLP comprises more than one heterologous polypeptides, which may be the same or different and wherein said each of said heterologous polypeptides are provided as fusion proteins with one or more TrV structural proteins.

13. A polynucleotide encoding a fusion protein selected from the group consisting of

(i) a fusion protein comprising a structural protein from a virus of the Dicistroviridae family selected from the group consisting of VP1, VP2, VP3, VP4 and VP0, or a functionally equivalent variant thereof, and a heterologous polypeptide, or

14. The polynucleotide according to the claim 13, wherein the fusion protein further comprises a non-structural protein (NS) from a virus of the Dicistroviridae family, or a functionally equivalent variant thereof.

15. The polynucleotide according to any of claims 13 or 14, wherein the virus of the Dicistroviridae family is the Triatoma virus (TrV).

16. The polynucleotide according to claim 15, wherein the fusion protein comprises the complete Triatoma virus structural protein precursor PI according to GenBank accession number AF 178440 or a functionally equivalent variant thereof.

17. The polynucleotide according to claim 16, wherein the fusion protein further comprises the non-structural protein NS of the Triatoma virus according to GenBank accession number AF 178440 or a functionally equivalent variant thereof.

18. The polynucleotide according to any of claims 13 to 17, wherein the heterologous polypeptide is located at a position selected from the group consisting of:

in VP1 structural protein, replacing the VP1 region from Ala681 to Trp688, in VP1 structural protein, replacing the VP1 region from Asp841 to Thr854 in VP1 structural protein, after Leu860,

in VP4 structural protein, in any region of its aminoacid sequence.

19. The polynucleotide according to any of claims 13 to 18, wherein the heterologous polypeptide comprises at least one epitope from an antigen selected from the group consisting of a viral antigen, a bacterial antigen, a fungal antigen, an environmental antigen or a tumor antigen.

20. The polynucleotide according to claim 19 wherein the antigen is selected from the group consisting of PFR-2, PFR-3, RAP-2, RAP-3, KETcl, GK-1, KETcl2 and HSP-70.

21. The polynucleotide according to any of claims 13 to 18, wherein the heterologous polypeptide is a first member of a binding pair.

22. The polynucleotide according to claim 21, wherein the first member of a binding pair is selected from the group consisting of a peptide comprising the tripeptide Arg- Gly-Asp, a peptide comprising the sequence XBBXBX (SEQ ID NO:22), wherein X represents any aminoacid and B represents Arg or Lys, and a peptide comprising the sequence XBBBXXBX (SEQ ID NO:23), wherein X represents any aminoacid and B represents Arg or Lys and a biotin acceptor peptide (BAP).

23. A vector comprising a polynucleotide according to any of claims 13 to 22.

24. A host cell comprising a polynucleotide according to any of claims 13 to 22 or a vector according to claim 23.

25. A process for obtaining a Dicistroviridae family virus VLP modified to express a heterologous polypeptide of interest comprising the steps of:

26. The process according to claim 25, wherein the host cell is additionally contacted with a polynucleotide comprising a sequence encoding the non-structural protein precursor (NS) of a virus of the Dicistroviridae family or a functionally equivalent variant thereof, under conditions suitable for the entry of said polynucleotide into the cell.

27. The process according to claim 26, wherein the polynucleotide encoding a fusion protein comprising a heterologous polypeptide and a the structural protein precursor (PI) of the virus or a functionally equivalent variant and the polynucleotide which comprises a sequence encoding the non-structural protein precursor (NS) of the virus or a functionally equivalent variant thereof are provided in the same polynucleotide or in different polynucleotides.

28. The process according to any of claims 25 to 27, further comprising recovering the VLPs from the culture obtained in step (ii).

29. The process according to any of claims 25 to 28, wherein the virus of the Dicistroviridae family is the Triatoma virus (TrV).

30. The process according to any of claims 25 to 29, wherein the heterologous polypeptide is inserted in the sequence encoding PI at (i) a nucleotide position corresponding to an amino acid inside at least one

TrV structural protein derived from PI,

(ii) a nucleotide position corresponding to the amino terminal end of at least one TrV structural protein derived from PI, and/or

(iii) a nucleotide position corresponding to the carboxy terminal end of at least one TrV structural protein derived from PI,

wherein said at least one TrV structural protein is the same TrV structural protein or is a different TrV structural protein, and/or wherein said heterologous polypeptide is the same polypeptide or is a different polypeptide.

31. The process according to claim 30, wherein the heterologous polypeptide is located between nucleotide positions which result in a fusion protein wherein the heterologous polypeptide is located at a position selected from the group consisting of:

between amino acid positions Ala681 and Trp688 in VP1 structural protein, - between amino acid positions Asp841 and Thr854 in VP1 structural protein, after amino acid position Leu860 in VP1 structural protein,

after amino acid positions Thr498 and Gln531 in VP3 structural protein, - after amino acid position Glu586 in VP3 structural protein, and/or

at any amino acid position in VP4 structural protein.

32. The process according to any of claims 25 to 31, wherein the heterologous polypeptide comprises at least one epitope from an antigenic protein.

33. The process according to claim 32, wherein the epitope is comprised by a viral antigen, a bacterial antigen, a fungal antigen, an environmental antigen or a tumor antigen.

34. The process according to any of claims 32 or 33, wherein the antigen is selected from the group comprising PFR-2, PFR-3, RAP-2, RAP-3, KETcl, GK-1, KETcl2 and HSP-70.

35. The process according to any of claims 25 to 31, wherein the heterologous polypeptide comprises at least a first member of a binding pair.

36. The process according to claim 35, wherein said first member of a binding pair is selected from the group consisting of a peptide comprising the tripeptide Arg-Gly- Asp, a peptide comprising the sequence XBBXBX (SEQ ID NO:22), wherein X represents any aminoacid and B represents Arg or Lys, and a peptide comprising the sequence XBBBXXBX (SEQ ID NO:23), wherein X represents any aminoacid and B represents Arg or Lys and a biotin acceptor peptide (BAP).

37. The process according to any of claims 35 or 36, further comprising contacting the VLPs with a second member of a binding pair under conditions adequate for the interaction between said first and second members of the binding pair to occur.

38. The process according to claim 37, wherein the first member of the binding pair is the biotinylated BAP and the second member of the binding pair is a molecule comprising a biotin-binding region.

39. The process according to claim 38, wherein the molecule containing a biotin- binding region is selected from the group comprising avidin, an avidin analog, streptavidin, and streptavidin analog.

40. A VLP obtainable by the process according to any of claims 25 to 39.

41. A vaccine or immunogenic composition comprising a VLP according to any of claims 1 to 12 and 40, or a polynucleotide according to any of claims 13 to 22, or a vector according to claim 23.

42. A VLP according to any of claims 1 to 12 and 40, or a polynucleotide according to any of claims 13 to 22, or a vector according claim 23, for use in the treatment of an infectious disease caused by a pathogenic organism and/or an immune reaction caused by an allergen from which the heterologous peptide is derived.

43. A RNA polynucleotide comprising in the 5' to 3' direction:

(ii) the 5 ' UTR of the TrV virus genome,

(iv) the intergenic region of the genome of TrV virus,

(v) a sequence region encoding the structural protein precursor PI of the Triatoma virus or a functionally equivalent variant thereof, (vi) the 3 ' UTR of the TrV virus genome and

(vii) a second autocatalytic ribozyme capable of cleaving the sequence containing said ribozyme at the 5' end of the ribozyme.

44. A DNA polynucleotide having at least one strand which is complementary to the RNA polynucleotide of claim 43, further comprising a transcriptional regulatory region which regulates the expression of said DNA polynucleotide.

45. The polynucleotide according to claims 43 or 44, wherein the first autocatalytic ribozyme is the hammerhead ribozyme (HamRz) and/or wherein the second autocatalytic ribozyme is the hepatitis delta virus ribozyme (HDVz).

46. The polynucleotide according to any of claims 43 to 45, wherein the sequence encoding the structural protein precursor PI of the Triatoma virus or the functionally equivalent variant thereof further comprises a polynucleotide sequence encoding a heterologous polypeptide which results in a fusion protein comprising at least one of the structural proteins of the Triatoma virus and the heterologous polypeptide.

47. The polynucleotide according to claim 46 wherein the polynucleotide sequence encoding the heterologous polypeptide is located within the sequence of the sequence encoding the structural protein precursor PI of the Triatoma virus so that, after expression, the heterologous polypeptide is located at a position selected from the group consisting of

between amino acid positions Thr97 and Lysl03in VP2 structural protein, - after amino acid position Ala251 in VP2 structural protein,

after amino acid positions Thr498 and Gln531 in VP3 structural protein, and/or

after amino acid position Glu586 in VP3 structural protein.

48. The polynucleotide according to claims 43 to 47, wherein the heterologous polypeptide comprises at least one epitope of an antigenic polypeptide.

49. The polynucleotide according to claim 48, wherein the antigenic polypeptide is selected from the group consisting of a viral antigen, a bacterial antigen, a fungal antigen, an environmental antigen or a tumor antigen.

50. The polynucleotide according to claim 49, wherein the antigen is selected from the group comprising PFR-2, PFR-3, RAP-2, RAP-3, KETcl, GK-1, KETcl2, and

HSP-70.

51. The polynucleotide according to claims 43 to 47, wherein the heterologous polypeptide comprises a first member of a binding pair.

52. The polynucleotide according to claim 51, wherein the first member of a binding pair is selected from the group consisting of a polypeptide comprising the tripeptide

Arg-Gly-Asp, a peptide comprising the sequence XBBXBX (SEQ ID NO:22), wherein X represents any aminoacid and B represents Arg or Lys, and a peptide comprising the sequence XBBBXXBX (SEQ ID NO:23), wherein X represents any aminoacid and B represents Arg or Lys, and a biotin acceptor peptide (BAP).

53. A process for obtaining an infectious Triatoma virus (TrV) comprising the steps of:

(i) contacting a host cell with a polynucleotide according to any of claims 43 to 52 under conditions suitable for the entry of said polynucleotide into the cell, and

54. The process according to claim 53, wherein step (i) further comprises contacting the host cell with a polynucleotide encoding the TrV NS non- structural protein precursor.

55. The process according to claims 53 or 54, further comprising recovering the TrV particles from the culture obtained in step (ii).

56. An infectious Triatoma virus (TrV) obtained by the process according to any of claims 53 to 55.

57. Method for killing insects comprising the administration of an infectious Triatoma virus (TrV) according to claim 56.

58. Method according to claim 57, wherein the insect is an haematophagous insect.

59. Method according to claim 58, wherein the insect is a member of the Triatominae family.