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  • C12N15/63—Introduction of foreign genetic material using vectors; Vectors; Use of hosts therefor; Regulation of expression
  • C12N15/79—Vectors or expression systems specially adapted for eukaryotic hosts
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  • A61P31/12—Antivirals
• • A—HUMAN NECESSITIES
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  • A61P31/00—Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
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  • A61P31/00—Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
  • A61P31/12—Antivirals
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• • A—HUMAN NECESSITIES
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  • C12N2770/00—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA ssRNA viruses positive-sense
  • C12N2770/00011—Details
  • C12N2770/24011—Flaviviridae
  • C12N2770/24111—Flavivirus, e.g. yellow fever virus, dengue, JEV
  • C12N2770/24141—Use of virus, viral particle or viral elements as a vector
  • C12N2770/24143—Use of virus, viral particle or viral elements as a vector viral genome or elements thereof as genetic vector
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
  • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
  • Y02A50/30—Against vector-borne diseases, e.g. mosquito-borne, fly-borne, tick-borne or waterborne diseases whose impact is exacerbated by climate change

Definitions

• This invention relates to chimeric flavivirus vectors and methods employing these vectors.
• Flaviviruses are small, enveloped positive-strand RNA viruses. Flavivirus proteins are produced by translation of a single, long open reading frame to generate a polyprotein, which is followed by a complex series of post-translational proteolytic cleavages of the polyprotein by a combination of host and viral proteases to generate mature viral proteins (Amberg et al., J. Virol. 73:8083-8094, 1999; Rice, "Flaviviridae,” In Virology, Fields (ed.), Raven-Lippincott, New York, 1995, Volume I, p. 937).
• the virus structural proteins are arranged in the polyprotein in the order C-prM-E, where "C” is capsid, "prM” is a precursor of the viral envelope-bound M protein, and “E” is the envelope protein. These proteins are present in the N-terminal region of the polyprotein, while the non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) are located in the C-terminal region of the polyprotein.
• a chimeric flavivirus that includes the C and non-structural proteins of the Yellow fever virus vaccine strain (YF 17D) and the prM and E proteins of a strain of attenuated Japanese encephalitis virus (SA 14-14-2) has been made.
• This chimera, designated ChimeriVax T -JE has been shown to induce the production of neutralizing antibodies against JE in immunized rhesus monkeys, as well as to protect these monkeys from clinical encephalitis after JE challenge, as compared with unimmunized controls.
• ChimeriVaxTM-JE was shown to meet preclinical safety requirements for a human vaccine (Monath et al., J. Virol. 74(4): 1742- 1751, 2000).
• ChimeriVax-D2 A similar chimera was made that includes the C and non-structural proteins of YF 17D and the prM and E proteins of a Dengue-2 strain.
• This chimera designated ChimeriVax-D2
• ChimeriVax-D2 was shown to induce neutralizing antibodies against Dengue-2 virus in rhesus monkeys, as well as to protect these monkeys from viremia after Dengue-2 challenge, as compared with unimmunized controls.
• ChimeriVax-D2 also was shown to be safe and genetically stable (Guirakhoo et al., J. Virol. 74(12):5477-5485, 2000).
• the invention provides methods for identifying sites in the envelope proteins of chimeric flaviviruses or genetically attenuated flaviviruses that are permissive for insertion of foreign peptides. These methods include the steps of: (i) introducing a nucleic acid molecule encoding a foreign peptide into a gene encoding a flavivirus envelope protein; (ii) generating a flavivirus vector including an envelope protein encoded by the gene, wherein the envelope protein contains the foreign peptide; and (iii) determining whether the flavivirus vector generated in step (ii) is permissive for the insertion.
• the flavivirus vectors can be chimeric flavivirus vectors that include, for example, the C and non-structural proteins of a first flavivirus and the prM and E proteins of a second flavivirus.
• the first and second flaviviruses can be selected from the group consisting of Japanese encephalitis, Dengue (serotype 1, 2, 3, or 4), Yellow fever (e.g., YF 17D), Murray Valley encephalitis, St.
• the foreign peptides inserted into the vectors of the invention can include epitopes derived from, for example, antigens of viral, bacterial, or parasitic pathogens, or can include epitopes derived from tumor-associated antigens. Examples of these peptides and others are provided below.
• the nucleic acid molecules can be introduced into the envelope genes of the flaviviruses, according to the methods of the invention, for example, randomly by transposon mutagenesis. Also, determination of whether the flavivirus vectors generated in step (ii) of the methods of the invention are permissive for the insertion can be carried out, for example, by analysis of (a) the infectivity of the flavivirus vectors, (b) the stability of the sequence of the foreign protein upon multiple passages of the vectors, (c) the growth properties of the flavivirus vectors, and/or (d) whether the flavivirus vectors can be neutralized with antibodies against the envelope protein of the first flavivirus. The methods of the invention can further include comparing the analysis of the flavivirus vectors with a similar analysis of the flavivirus from which it was derived.
• the invention also includes flavivirus vectors that include envelope proteins that contain foreign peptides.
• the flavivirus vectors can be chimeric flaviviruses including the prM and E proteins of a first flavivirus and the C and non-structural proteins of a second flavivirus.
• the first and second flaviviruses can be selected from the group consisting of Japanese encephalitis, Dengue (serotype 1, 2, 3, or 4), Yellow fever (e.g., YF 17D), Murray Valley encephalitis, St.
• the flavivirus vectors can, alternatively, be a genetically attenuated flavivirus, such as Yellow Fever YF 17D.
• the foreign peptides inserted into the vectors can include epitopes derived from antigens of viral, bacterial, or parasitic pathogens.
• the foreign peptides can include epitopes derived from tumor-associated antigens.
• compositions that include the flavivirus vectors described above and pharmaceutically acceptable carriers or diluents, as well as methods of delivering peptides to patients by administering to the patients such compositions. These methods can be carried out, for example, when the peptides are antigens, to induce an immune response to pathogens or tumors from which the antigens are derived.
• the invention also includes use of these compositions for the delivery of peptides, as well as their use in the preparation of medicaments for delivery of peptides.
• the invention also includes nucleic acid molecules that include the genomes of the flaviviruses described above or the complements thereof.
• chimeric flavivirus vectors that can be used in the invention are sufficiently attenuated so as to be safe, and yet are able to induce protective immunity to the flaviviruses from which the envelope proteins in the chimeras are derived and, in particular, the epitopes inserted into the chimeras. Additional safety comes from the fact that the vectors used in the invention are chimeric, thus eliminating the possibility of reversion to wild type.
• An additional advantage of the vectors used in the invention is that flaviviruses replicate in the cytoplasm of cells, so that the virus replication strategy does not involve integration of the viral genome into the host cell, providing an important safety measure.
• a single vector of the invention can be used to deliver multiple epitopes from a single antigen, or epitopes derived from more than one antigen.
• FIG. 1 is a schematic representation of a transposon mutagenesis method carried out with the gene encoding the JE envelope.
• Fig. 2 shows the results of PCR analysis of Tn5 insertion mutants of the gene encoding the JE envelope.
• Stable clones harboring a transposon in the JE envelope are shown in lanes 1, 2, 8, and 10; clones harboring a transposon within the pUC19 vector are shown in lanes 3 and 4; unstable clones harboring a transposon in the JE envelope are shown in lanes 5-7 and 9; and a 1 kilobase marker is shown in lane 11.
• Fig. 3 shows the results of PCR mapping of select mutant plasmids. This analysis confirmed the random nature of the insertion into the JE envelope. Lanes 1-13 show the PCR products of 13 clones, while lane 14 contains a 1 kilobase marker.
• Fig. 4 shows the amino acid sequences of five mutant clones that were selected for transfection of Vero cells.
• the JE envelope sequences are in boldface and the insert sequences following transposition are underlined.
• the remaining sequences which are repeated sets of three amino acids each that are on the left side of the first dash and on the left side of the second dash in each line, are artifacts of the transposon mutagenesis.
• Fig. 5 is a schematic representation of the envelope glycoprotein of JE, which shows the locations of inserts relative to defined conformational epitopes of the protein.
• the arrows pinpoint the approximate insertion sites for 5 independent JE envelope mutants that were selected for transfection of Vero cells.
• the numbers in brackets indicate the JE envelope amino acid that precedes the 19 amino acid insert.
• Fig. 6 shows the results of RT-PCR analysis of cDNA synthesized from RNA extracted from Vero cells that have been transfected with RNA made from 5 unique clones (2 in duplicate).
• a 1.9 kilobase insert that includes the 57 basepair linker was amplified from each of the clones, and confirms the production of progeny virus.
• a 1 kilobase marker is fractionated in lane 1. Lanes 2-8 correspond to clone 1-10-2, clone I- 10-3, clone II-4-3, clone II-4-6, clone 1-1, clone III-6, and clone IV-8-l, respectively.
• Fig. 7 shows the results of PCR analysis of clone I- 10 cDNA at P2 through P6 (lanes 2-6 and 8-12, respectively).
• the samples fractionated on the left panel were obtained using JE envelope specific primers, while the samples fractionated on the right panel were obtained using a transposon-specific primer.
• a 1 kilobase marker is fractionated in lane 1 and a 100 basepair marker is fractionated in lane 7.
• Fig. 8 shows the nucleotide sequences of the RT-PCR products of infectious clone I- 10 at P2 through P6, aligned with the plasmid I- 10 sequence prior to transfection.
• the arrows indicate two cysteine residues in the insert that have the potential to form a disulfide bond, possibly stabilizing the peptide on the envelope protein and presenting it on the surface of the molecule.
• Fig. 9 is a schematic representation of the 3 -dimensional structure of the JE envelope glycoprotein, showing that the permissive site at amino acid position 287 is located between the central (I) and the dimerization (II) domains, and appears to be surface exposed.
• Fig. 10 is a graph showing the growth properties of the I- 10 infectious clone.
• the line with the triangles corresponds to the titer of the transposon mutant I- 10, while the line with the squares corresponds to the titer of the YF/JE parent virus.
• Fig. 11 is a graph showing the results of a neutralization assay of transposon mutant I- 10.
• the line with the diamond corresponds to the titer of samples incubated with anti-JE serum, the squares correspond to samples incubated with normal serum, and the dashed line shows the average.
• Fig. 12 is a graph showing the results of a neutralization assay of the YF/JE reference.
• the line with the diamond corresponds to the titer of samples incubated with anti-JE serum, the squares correspond to samples incubated with normal serum, and the dashed line shows the average.
• the invention provides methods of identifying sites in the envelope proteins of chimeric flaviviruses or genetically attenuated flaviviruses (e.g., YF 17D) into which foreign peptides can be introduced, chimeric flavivirus vectors having envelope proteins that include such peptides, and methods of delivering these peptides by administration of the vectors in order to, for example, induce an immune response to a pathogen from which an introduced peptide is derived. Details of these vectors, peptides, and methods are provided below.
• Chimeric viruses that can be used in the invention consist of a first flavivirus (i.e., a backbone flavivirus) in which a structural protein (or proteins) has been replaced with a corresponding structural protein (or proteins) of a second virus.
• the chimeras can consist of a first flavivirus in which the prM and E proteins have been replaced with the prM and E proteins of a second virus.
• the chimeric viruses that are used in the invention can be made from any combination of viruses.
• flaviviruses that can be used in the invention, as first or second viruses include mosquito-borne flaviviruses, such as Japanese encephalitis, Dengue (serotypes 1-4), Yellow fever, Murray Valley encephalitis, St.
• a specific example of a type of chimeric virus that can be used in the invention is the yellow fever human vaccine strain, YF 17D, in which the prM and E proteins have been replaced with prM and E proteins of another flavivirus, such as Japanese encephalitis virus, West Nile virus, St. Louis encephalitis virus, Murray Valley encephalitis virus, a Dengue virus, or any other flavivirus, such as one of those listed above.
• chimeric flaviviruses which were deposited with the American Type Culture Collection (ATCC) in Manassas, Virginia, U.S.A. under the terms of the Budapest Treaty and granted a deposit date of January 6, 1998, can be used in the invention: Chimeric Yellow Fever 17D/Japanese Encephalitis SA14-14-2 Virus (YF/JE Al .3; ATCC accession number ATCC VR-2594) and Chimeric Yellow Fever 17D/Dengue Type 2 Virus (YF/DEN-2; ATCC accession number ATCC VR-2593).
• ATCC American Type Culture Collection
• nucleic acid sequences encoding a peptide are inserted into the envelope gene using standard methods of molecular biology. Preferably, such nucleic acid sequences are randomly inserted into the envelope gene, to facilitate the creation of a library of insertion mutants. However, a nucleic acid sequence can, alternatively, be inserted a specific point in an envelope gene and tested for efficacy.
• the latter approach may be desirable, for example, when a particular site has been identified as being permissive for insertion of a first foreign sequence and it is desired to confirm that it is also permissive for insertion of a second sequence that may, for example, differ in length or predicted secondary structure from the first foreign sequence.
• Random insertion of nucleic acid sequences can be achieved, for example, by the use of a transposon mutagenesis approach.
• a Tn5 transposition system can be used (Goryshin et al., J. Biol. Chem. 273:7367, 1998).
• the EZ::TN Insertion System which is manufactured by Epicentre Technologies (Madison, WI, U.S.A.), can be used. Details of the use of this system in the invention are provided further below.
• a cloned flavivirus envelope gene is subjected to mutagenesis with transposons that include sequences that encode peptides.
• a library of mutants that include randomly integrated transposons in flavivirus envelope genes is generated and, if desired, the insertion sites are mapped and/or sequenced.
• Full length genomic RNA that includes mutant envelope genes is then generated and used to make mutant viruses, which are then characterized for permissiveness to insertion of the transposons.
• the viruses can be analyzed for permissiveness by, for example, determination of infectivity, genomic stability, growth properties, and neutralization. Details of the use of this transposon mutagenesis system are provided below, in the context of the chimeric flavivirus ChimeriVaxTM-JE (also see Fig. 1). However, the methods can be used with any of the chimeras described herein.
• the vectors of the invention can be used in the delivery of any peptide or protein of prophylactic or therapeutic value.
• the vectors of the invention can be used in the induction of an immune response (prophylactic or therapeutic) to any protein-based antigen that is inserted into a chimeric flavivirus envelope protein.
• such an antigen not derived from the second flavivirus of the chimera is that a nucleic acid sequence encoding the antigen be inserted at a permissive site within the envelope gene of a chimeric flavivirus, as described herein. Standard methods of molecular biology can be used to insert the antigen-coding nucleic acid molecules into chimera envelope genes, at permissive sites, which are identified as is described elsewhere herein.
• the vectors of the invention can each include a single epitope.
• multiple epitopes can be inserted into the vectors, either at a single site (i.e., as a polytope, in which the different epitopes can be separated by a flexible linker, such as a polyglycine stretch of amino acids), at different sites, or in any combination thereof.
• the different epitopes can be derived from a single species of pathogen, or can be derived from different species and/or different genuses.
• Antigens that can be used in the invention can be derived from, for example, infectious agents such as viruses, bacteria, and parasites.
• antigens from the pathogens listed in Table 2, below can be used. Specific examples of such antigens include those listed in Table 3.
• specific examples of epitopes that can be inserted into the vectors of the invention are provided in Table 4.
• epitopes that are used in the vectors of the invention can be B cell epitopes (i.e., neutralizing epitopes) or T cell epitopes (i.e., T helper and cytotoxic T cell-specific epitopes).
• the vectors of the invention can be used to deliver antigens in addition to pathogen-derived antigens.
• the vectors of the invention can be used to deliver tumor-associated antigens for use in immunotherapeutic methods against cancer.
• Numerous tumor-associated antigens are known in the art and can be used in the invention.
• cancers and corresponding tumor associated antigens are as follows: melanoma (NY-ESO-1 protein (specifically CTL epitope located at amino acid positions 157-165), CAMEL, MART 1, gplOO, tyrosine-related proteins TRP1 and 2, and MUCl)); adenocarcinoma (ErbB2 protein); colorectal cancer (17-1A, 791Tgp72, and carcinoembryonic antigen); prostate cancer (PSA1 and PSA3).
• Heat shock protein hspl 10
• hspl 10 can also be used as such an antigen.
• exogenous proteins that encode an epitope(s) of an allergy-inducing antigen to which an immune response is desired may be used.
• the vectors of the invention can include ligands that are used to target the vectors to deliver peptides, such as antigens, to particular cells (e.g., cells that include receptors for the ligands) in subjects to whom the vectors administered.
• the size of the peptide or protein that is inserted into the vectors of the invention can range in length from, for example, from 5-500 amino acids in length, for example, from 10-100, 20-55, 25-45, or 35-40 amino acids in length.
• the feasibility of using any particular desired peptide can easily be determined using the methods described herein.
• the vectors of the invention are administered in amounts and by using methods that can readily be determined by persons of ordinary skill in this art.
• the vectors can be administered and formulated, for example, in the same manner as the yellow fever 17D vaccine, e.g., as a clarified suspension of infected chicken embryo tissue, or a fluid harvested from cell cultures infected with the chimeric yellow fever virus.
• the vectors of the invention can be formulated as sterile aqueous solutions containing between 100 and 1,000,000 infectious units (e.g., plaque-forming units or tissue culture infectious doses) in a dose volume of 0.1 to 1.0 ml, to be administered by, for example, intramuscular, subcutaneous, or intradermal routes.
• flaviviruses may be capable of infecting the human host via the mucosal routes, such as the oral route (Gresikova et al., "Tick-borne Encephalitis," In The Arboviruses, Ecology and Epidemiology, Monath (ed.), CRC Press, Boca Raton, Florida, 1988, Volume IV, 177- 203), the vectors can be administered by a mucosal route.
• the vectors When used in immunization methods, the vectors can be administered as a primary prophylactic agent in adults or children at risk of infection by a particular pathogen.
• the vectors can also be used as secondary agents for treating infected patients by stimulating an immune response against the pathogen from which the peptide antigen is derived.
• adjuvants that are known to those skilled in the art can be used.
• Adjuvants that can be used to enhance the immunogenicity of the chimeric vectors include, for example, liposomal formulations, synthetic adjuvants, such as (e.g., QS21), muramyl dipeptide, monophosphoryl lipid A, or polyphosphazine.
• these adjuvants are typically used to enhance immune responses to inactivated vaccines, they can also be used with live vaccines.
• mucosal adjuvants such as the heat-labile toxin of E. coli (LT) or mutant derivations of LT can be used as adjuvants.
• genes encoding cytokines that have adjuvant activities can be inserted into the vectors.
• genes encoding cytokines such as GM-CSF, IL-2, IL-12, IL-13, or IL-5, can be inserted together with foreign antigen genes to produce a vaccine that results in enhanced immune responses, or to modulate immunity directed more specifically towards cellular, humoral, or mucosal responses.
• the vectors of the invention can be used in gene therapy methods to introduce therapeutic gene products into a patient's cells and in cancer therapy.
• genes encoding therapeutic gene products are inserted into permissive sites in the vectors.
• the following experimental example shows the identification of permissive sites in ChimeriVaxTM-JE.
• the methods described in this example can be used with other chimeric flaviviruses, such as those described above, as well.
• the Yellow fever 17D (YF 17D) live attenuated vaccine strain has been used in humans for the past 60 years, has an excellent safety record, and provides long-lasting immunity after administration of a single dose.
• ChimeriVaxTM-JE is a live, attenuated recombinant vaccine strain in which the genes encoding the structural proteins (PrME) of YF 17D have been replaced with the corresponding genes from the genetically attenuated Japanese encephalitis (JE) virus SA14-14-2. Both capsid and all nonstructural (NS) genes responsible for intracellular replication of this chimera are derived from the YF 17D vaccine strain.
• ChimeriVaxTM-JE As is noted above, an infectious molecular clone of ChimeriVaxTM-JE (YF/JE) has previously been described. In the experiments described below, ChimeriVaxTM-JE was evaluated as to its suitability as a delivery vehicle for biologically relevant peptides.
• the EZ::TN In-Frame Linker Insertion Kit ® (Epicentre) is a fast and efficient method for randomly inserting 19 amino acid peptides in-frame into proteins encoded by cloned DNA for a variety of applications. Using this approach, we have chosen to identify sites within the envelope gene of ChimeriVaxTM-JE that are permissive to foreign DNA. As is discussed in further detail below, random mutagenesis in E. coli of the gene encoding the JE envelope protein with EZ::TN identified a bank of stable insertion mutants that carried the 57 basepairs fragment that encodes the 19 amino acid peptide. DNA sequence analysis, restriction mapping, and PCR studies confirmed both the exact location of the transposon and the random nature of insertion.
• YF/JE viral RNA was extracted from infected Vero cells using Trizol reagent (Gibco BRL). Following cDNA synthesis with the FNOR antisense primer (see below), the gene encoding the JE SA14-14-2 envelope was amplified by XL-PCR with TNI .F/TN2.R primers (see below), and directionally cloned by conventional methods into pUC19 (New England Biologicals, NEB, U.S.A.) using Kpnl and Pstl recognition sequences incorporated at the 5' ends of each oligonucleotide, generating pJEel. PCR was carried out using a GeneAmp PCR System 2400 (Perkin Elmer). Transposon mutagenesis and mapping of insertion sites
• Insertion mutagenesis was performed on pJEel using the EZ: :TN In-Frame Linker Insertion Kit (EPICENTRE Technologies, U.S.A.), according to manufacturer's instructions.
• the EZ::TN ⁇ NotI/Kan-3> transposon contains a kanamycin resistance gene flanked by Not I restriction sites. As is discussed further below, removal of the kanamycin resistance gene following Notl digestion and re-ligation generates a 19 codon insertion that can be read in all three reading frames.
• Insertion mutants were identified in E. coli by selection on LB agar plus kanamycin (50 ⁇ g/ml). PCR with TNI .F/TN2.R on select kanamycin-resistant clones following transposition revealed that 40% of clones stably maintained the transposon in the JE envelope (Fig. 2). Insertion sites were mapped by PCR (Pwo DNA Polymerase, Boehringer Mannheim Roche) using Tn5-specific primers TNI .F and NotI/KAN-3 RP- 2, which showed that the Tn5 transposon inserted randomly into the JE envelope (Fig. 3). Unique clones were selected for sequencing and generation of full length mutant genomic RNA.
• the amino acid sequences of five mutant clones that were selected for transfection of Vero cells is shown in Fig. 4.
• the locations of the inserts relative to defined conformation epitopes on the envelope protein of JE virus is shown in Fig. 5.
• the insertion sites were determined by DNA sequencing, and inserts were located by comparison to a predicted 3D structure of the JE envelope (Kolaskar et al., Virology 261:31-42, 1999). Four of the five insertion sites appear to be surface exposed. Sequencing was performed using a CEQTM 2000 DNA Analysis system (Beckman Coulter) and a CEQ 2000 Dye Terminator Cycle Sequencing Kit. Data were analyzed using SEQUENCHERTM, Version 4.0.5. (Gene Codes Corporation).
• the antibiotic resistance marker was removed from stable E. coli clones, which were then re-ligated, leaving a 57 basepair in-frame insertion that included a 9-basepair target site sequence duplication that flanks the transposon.
• RT-PCR using TN1.F/TN2.R on cDNA synthesized from RNA extracts of cell monolayers amplified a 1.9 kilobase insert that harbors the 57 basepair linker, and confirms the production of progeny virus.
• PCR analysis of clone I- 10 from P2 through P6 shows that this clone is stable through P6, and that its insertion site, at amino acid 287, is permissive for the insertion of foreign DNA.
• PCR was carried out with JE envelope gene-specific primers (TN1.F/TN2.R) and a transposon-specific primer (TNl.F/TMOS.R) (Fig. 7).
• Fig. 9 depicts a 3-D structure of the JE virus envelope glycoprotein, and shows that position 287 is located between the central (I) domain and the dimerization (II) domain and appears to be surface exposed.
• transposon mutant 1-10 The biological properties of transposon mutant 1-10 were determined and compared with those of ChimeriVaxTM-JE.
• the growth properties of clone I- 10 were determined. As is shown in Fig. 10, the mutant infectious clone I- 10 shows similar growth kinetics as the ChimeriVaxTM- JE parent, but grows to a slightly lower titer, reaching 8e5 PFU/ml, as compared to le7 PFU/ml for YF/JE. Also, the mutant infectious clone I- 10 was found to induce a cytopathic effect in Vero cells, analogous to its YF/JE parent. Plaque reduction neutralization (PRNT) assays were then carried out.
• PRNT Plaque reduction neutralization
• VIRUSES Flaviviridae
• Hepatitis C virus e.g., genotypes la, lb, 2a, 2b, 2c, 3a, 4a, 4b, 4c, and 4d
• Papoviridae e.g., genotypes la, lb, 2a, 2b, 2c, 3a, 4a, 4b, 4c, and 4d
• Rhinovirus Poliovirus Herpesviridae Hepatitis A virus .
• Herpes simplex virus type I Herpes simplex virus, type II Cytomegalovirus Epstein Barr virus Varicella-Zoster virus
• Alphavirus Rubella virus Paramyxo viridae Respiratory syncytial virus
• PARASITES Plasmodium spp.

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• 2002
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