WO2007005766A1 - Genomic nucleic acid sequence for cyanovirin-n and signal peptide thereof - Google Patents

Abstract

An isolated or purified nucleic acid encoding a CV-N signal peptide, wherein the CV-N signal peptide comprises an amino acid sequence that has about 50% or greater sequence identity to SEQ ID NO: 2, and an isolated or purified nucleic acid comprising a genomic nucleic acid sequence encoding a cyanovirin-N (CV-N) polypeptide, are provided herein. Also provided are vectors and cells comprising the aforementioned nucleic acids, a method of producing a polypeptide, and a method of inhibiting a viral infection in a mammal. A polypeptide comprising the CV-N signal peptide also is provided.

Description

GENOMIC NUCLEIC ACID SEQUENCE FOR CYANOVIRIN-N AND SIGNAL

PEPTIDE THEREOF

BACKGROUND OF THE INVENTION

[0001] Acquired immune deficiency syndrome (AIDS) is a fatal disease. In 2004, nearly 40 million people were estimated to be living with HIV globally, and more than 3 million were reported to have died from AIDS. Nearly 5 million people acquired the human immunodeficiency virus (HIV) in 2004 {AIDS Epidemic Update 2004, Joint United Nations Programme on HIV/AIDS). The AIDS virus was first identified in 1983. It is the third known T-lymphotropic virus (HTLV-III), and it has the capacity to replicate within cells of the immune system, causing profound cell destruction. The AIDS virus is a retrovirus, i.e., a virus that uses reverse transcriptase to replicate its RNA genome into DNA. Two distinct families of HIV have been described to date, namely HIV-I and HIV-2. The acronym HIV is used herein to refer to human immunodeficiency viruses generically. [0002] HIV exerts profound cytopathic effects on the CD4⁺ helper/inducer T-cells, thereby severely compromising the immune system. HIV infection also results in neurological deterioration and, ultimately, in death of infected individuals. During the period of time from initial HIV infection to the appearance of symptoms, or death, due to AIDS, infected individuals can spread the infection further, such as via sexual contact, exchange of contaminated needles during i.v. drug abuse, transfusion of blood or blood products, or maternal transfer of HIV to a fetus or newborn. Thus, there is not only an urgent need for effective therapeutic agents to inhibit the onset of AIDS in individuals already infected with HIV, but also for methods of preventing of the spread of HIV. The need for effective anti- HIV therapeutics is particularly acute in sub-Saharan Africa, which is home to more than 60% of all people living with HIV globally. The World Health Organization (WHO) has assigned an urgent international priority to the search for an effective anti-HIV prophylactic virucide to help curb the further expansion of the AIDS pandemic (see Baiter, Science, 266, 1312-1313 (1994), Merson, Science, 260, 1266-1268 (1993), Taylor, NIH Res., 6, 26-27, (1994), Rosenberg et al., Sex. Transm. Dis., 20, 41-44 (1993), and Rosenberg, Am. J. Public Health, 82, 1473-1478 (1992)).

[0003] The field of viral therapeutics has developed in response to the need for agents effective against retroviruses, especially HIV. A typical course of treatment currently involves three classes of FDA-approved antiretroviral drugs: nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) (e.g., AZT), protease inhibitors (PIs) (e.g., nelfinavir), and non-nucleoside reverse transcriptase inhibitors (NNRTIs) (e.g., nevirapine). The recommended treatment for HIV is a combination of three or more HIV drugs called Highly Active Anti-Retroviral Therapy, or HAART (see Shafer et al., Biomed. Pharmacother., 53, 73-86 (1999)). Although HAART has proven very effective in reducing viral loads in many patients, the utility of HAART is limited by a number of side effects, including the development of drug resistance, difficulties maintaining long-term adherence, and drug- related toxicities (see Mocroft et al., J. Antimicrobial Chemotherapy, 54, 10-13 (2004)). Such side effects can lead to immunological failure and clinical progression of the disease. Thus, it is now increasingly apparent that agents acting as early as possible in the viral replicative cycle are needed to inhibit infection of newly produced uninfected immune cells generated in the body in response to the virus-induced killing of infected cells. Also, it is essential to neutralize or inhibit new infectious virus produced by infected cells. [0004] To circumvent the problems associated with HAART, researchers have developed HIV vaccines utilizing gene transfer methodologies. For example, viral and bacterial vectors encoding HIV epitopes have been shown to elicit both humoral and cell-mediated immune responses in animals (see, e.g., Yoshida et al., Clin. Exp. Immunol, 124, 445-52 (2001), and Paterson et al., Expert Rev. Vaccines, 5(4 Suppl), Sl 19-34 (2004)). One of the many challenges of genetic vaccination for HIV is the ability to achieve distribution of the immunogen to a sufficient number of cells so as to generate an effective immune response. Of course, one way to enhance distribution of an antigen encoded by a particular gene transfer vector is to develop more efficient vector systems. In addition, antigen distribution can be enhanced at the cellular level following vaccine administration. In this regard, vector inserts (i.e., transgenes) could be engineered to contain, for example, elements that promote secretion of the antigenic polypeptide encoded therein from cells (e.g., signal peptides), such that the polypeptide can exert an effect e.g., an immunogenic or therapeutic effect, on a different cell, as well as elements that promote uptake of polypeptides by cells. [0005] Therefore, new antiviral polypeptides, nucleic acids encoding such polypeptides, and methods for producing and using such polypeptides are needed. The invention provides such polypeptides, nucleic acids, and methods. These and other objects of the present invention, as well as additional inventive features, will become apparent from the description provided herein.

BRIEF SUMMARY OF THE INVENTION

[0006] The invention provides an isolated or purified nucleic acid comprising a nucleic acid sequence that encodes a CV-N signal peptide, wherein the CV-N signal peptide comprises an amino acid sequence that has about 50% or greater sequence identity to SEQ ID NO: 2. The invention also provides an isolated or purified nucleic acid comprising a genomic nucleic acid sequence encoding a CV-N polypeptide. The invention further provides vectors, cells, and pharmaceutical compositions comprising the aforementioned nucleic acids. [0007] Additionally, the invention provides a method of producing a polypeptide comprising contacting a cell with a nucleic acid of the invention, whereby the polypeptide is produced. The invention further provides a method of inhibiting a viral infection in a mammal, which method comprises administering to a mammal a viral infection-inhibiting amount of a nucleic acid, vector, or cell of the invention to the mammal. [0008] A polypeptide comprising a CV-N signal peptide also is provided, wherein the CV-N signal peptide comprises an amino acid sequence that has about 50% or greater sequence identity to SEQ ID NO: 2.

DETAILED DESCRIPTION OF THE INVENTION

[0009] The terms "cyanovirin-N" and "CV-N," as used herein, refer to the cyanovirin-N polypeptide having the amino acid sequence of SEQ ID NO: 5, or any related, functionally equivalent polypeptide, fragment, or derivative thereof. CV-N and related polypeptides are described, for example, in U.S. Patents 5,843,882, 6,015,876, and 6,420,336. By definition, a related, functionally equivalent polypeptide, fragment, or derivative of a CV-N polypeptide (a) contains an amino acid sequence of at least nine amino acids that is identical to any subsequence of at least nine contiguous amino acids of the CV-N polypeptide, and, (b) is capable of specifically binding to a virus, more specifically a primate immunodeficiency virus, more specifically HIV-I, HIV-2, or SIV, or to an infected host cell expressing one or more viral antigen(s), more specifically an envelope glycoprotein, such as gρl20, of the respective virus.

[0010] The term "CV-N signal peptide," as used herein, refers to a signal peptide provided by the invention, which comprises an amino acid sequence that has about 50% or greater sequence identity to the amino acid sequence of the native CV-N signal peptide (SEQ ID NO: 2).

[0011] The term "signal peptide," as used herein, refers to an amino acid sequence, typically located at the amino terminus of an immature protein or polypeptide (e.g., prior to secretion from a cell and associated processing and cleavage), which directs the secretion of the protein or polypeptide from the cell in which it is produced. The signal peptide typically is removed from an immature protein or polypeptide prior to or during secretion and, thus, is not present in the mature, secreted polypeptide.

[0012] The term "isolated" as used herein with reference to a nucleic acid, polypeptide, or cell, means that the nucleic acid, polypeptide, or cell has been removed from its natural environment. Similarly, the term "purified" as used herein with reference to a nucleic acid, polypeptide, or cell, means that the nucleic acid, polypeptide, or cell, whether it has been removed from nature or synthesized and/or amplified under laboratory conditions, has been increased in purity, wherein "purity" is a relative term and does not mean "absolute purity." [0013] The term "genomic" as used herein to describe a nucleic acid sequence means that the nucleic acid sequence corresponds to a naturally occurring nucleic acid sequence (e.g., a nucleic acid sequence obtained from the genome of a particular organism). Genomic sequences typically contain non-coding regions, such as introns. A genomic nucleic acid sequence can be obtained directly from the genome of a particular organism, or it can be synthetically generated such that it comprises a nucleic acid sequence identical to a nucleic acid sequence found in nature. One of ordinary skill in the art will appreciate that synthetic derivation of a genomic nucleic acid sequence is preferable in instances where large-scale isolation and purification of a naturally-occuring genomic nucleic acid sequence is not feasible or cost-effective.

[0014] The term "non-genomic" as used herein to describe a nucleic acid sequence means that the nucleic acid sequence does not correspond to any known naturally occurring nucleic acid sequence. Non-genomic nucleic acid sequences encompass cDNA sequences and nucleic acid sequences otherwise derived from mRNA sequences or from the amino acid sequence of a protein (e.g., using the genetic code). Non-genomic sequences typically do not comprise non-coding regions (e.g., introns).

[0015] The term "nucleic acid" as used herein means a polymer of nucleotides (i.e., a polynucleotide) and encompasses DNA and RNA. Nucleic acids can be single-stranded or double-stranded, and can contain non-natural or altered nucleotides. The term "nucleic acid sequence" refers to the sequence (i.e., order) of the nucleotides of the nucleic acid or portion thereof, which sequence encodes a sequence of amino acids. In this regard, a nucleic acid can comprise more than one nucleic acid sequence (e.g., two or more regions of the nucleic acid can have sequences that are the same or different).

[0016] A "fragment" of a nucleic acid or nucleic acid sequence, as used herein, means a contiguous portion of the nucleic acid or nucleic acid sequence comprising about 5 or more (e.g., about 10 or more), such as about 15 or more (e.g., about 20 or more), or even about 25 or more (e.g., about 30 or more) or about 35 or more (e.g., about 40 or more) nucleotides. [0017] The term "polypeptide," as used herein, means a polymer of two or more amino acid residues linked by a peptide bond, and encompasses proteins and peptides. A polypeptide "fragment," as used herein, means a contiguous portion of a polypeptide comprising about 5 or more (e.g., about 10 or more), such as about 15 or more (e.g., about 20 or more), or even about 25 or more (e.g., about 30 or more) or about 35 or more (e.g., about 40 or more) amino acid residues. [0018] The term "sequence identity," as used herein, is generally expressed as a percentage and refers to the percent of amino acid residues or nucleotides, as appropriate, that are identical as between two sequences when optimally aligned. For the purposes of this invention, sequence identity means the sequence identity determined using the well-known Basic Local Alignment Search Tool (BLAST), which is publicly available through the National Cancer Institute/National Institutes of Health (Bethesda, Maryland) and has been described in printed publications (see, e.g., Altschul et al., J. MoI. Biol, 215(3), 403-10 (1990)).

[0019] The invention provides an isolated or purified nucleic acid comprising a nucleic acid sequence that encodes a CV-N signal peptide, wherein the CV-N signal peptide comprises an amino acid sequence that has about 50% or greater sequence identity to SEQ ID NO: 2. SEQ ID NO: 2 is the amino acid sequence of the CV-N signal peptide native to the cyanobacterium species Nostoc ellipsosporum. Preferably, the nucleic acid of the invention encodes a CV-N signal peptide comprising the amino acid sequence of SEQ ID NO: 2. However, one of ordinary skill in the art will appreciate that amino acid sequences that are different from, but are substantially identical to, SEQ ID NO: 2 also can exhibit the signal peptide activity of SEQ ID NO: 2 (i.e., the ability to direct the secretion of a polypeptide from a cell) to a greater or lesser degree. By "substantially identical" is meant sufficient identity to impart the polypeptide with such signal peptide activity. Thus, the nucleic acid of the invention can comprise a nucleic acid sequence that encode a CV-N signal peptide that shares regions of amino acid identity with SEQ ID NO: 2. In this regard, the nucleic acid sequence encodes a CV-N signal peptide comprising an amino acid sequence that has about 50% or greater sequence identity (e.g., about 60% or greater, about 70% or greater, about 80% or greater, or about 90% or greater sequence identity) to SEQ ID NO: 2. Preferably, the nucleic acid sequence encodes a CV-N signal peptide that has about 75% or greater sequence identity (e.g., about 75% or greater, about 85% or greater, or about 95% or greater sequence identity) to SEQ ID NO: 2. Desirably, the nucleic acid sequence encodes a CV-N signal peptide that has about 90% or greater sequence identity (e.g., about 95% or greater, about 97% or greater, or about 99% or greater sequence identity) to SEQ ID NO: 2.

[0020] The nucleic acid sequence encoding the CV-N signal peptide can be a genomic or non-genomic sequence. It is well within the skill of the ordinary artisan to determine non- genomic nucleic acid sequences that encode the CV-N signal peptide. For instance, non- genomic nucleic acid sequences encoding the amino acid sequence of SEQ ID NO: 2, or an amino acid sequence with a given percent identity thereto can be deteπnined from the amino acid sequence itself using the genetic code. A genomic nucleic acid sequence encoding the CV-N signal peptide is provided by the invention described herein, for example, by SEQ ID NO: 1. Other genomic nucleic acid sequences encoding a CV-N signal peptide (e.g., orthologs or paralogs of SEQ ID NO: 1) can be identified and isolated using the nucleic acid sequence of SEQ ID NO: 1, SEQ ID NO:4, or a fragment thereof, for example, in DNA hybridization studies. A preferred nucleic acid of the invention comprises the nucleic acid sequence of SEQ ID NO: 1, which encodes a CV-N signal peptide comprising the amino acid sequence of SEQ ID NO: 2.

[0021] The isolated or purified nucleic acid of the invention can further comprise, in addition to the nucleic acid sequence encoding the CV-N signal peptide, a nucleic acid sequence encoding a target polypeptide. The "target" polypeptide can be any polypeptide that is desired to be excreted from a cell. The nucleic acid sequences encoding the CV-N signal peptide and the target polypeptide preferably are arranged relative to one another (and relative to any promoter or regulatory sequences that might be present) such that they are expressed as a single polypeptide, desirably with the CV-N signal peptide located at the amino-terminus. In other words, the nucleic acid preferably encodes at least one polypeptide that comprises both the amino acid sequence of the target polypeptide and the amino acid sequence of the CV-N signal peptide, wherein the CV-N signal peptide is preferably located at the amino terminus of the target polypeptide. When the nucleic acid sequences are arranged in this manner, the CV-N signal peptide, desirably, can direct the secretion of the target polypeptide. It is within the skill of the ordinary artisan using the general knowledge available in the art to determine the appropriate arrangement of such sequences so as to achieve the desired result.

[0022] Suitable target polypeptides include, for example, polypeptides that have significant commercial or non-commercial (e.g., research) value, or polypeptides that have a therapeutic or prophylactic effect towards a disease or disorder (e.g., viral infection) in an animal, such as a mammal, especially a human.

[0023]. The CV-N signal peptide is especially suitable for directing the secretion of a CV- N polypeptide. Accordingly, the isolated or purified nucleic acid of the invention preferably comprises a nucleic acid sequence encoding a CV-N polypeptide in addition to the nucleic acid sequence encoding the CV-N signal peptide. Desirably, the CV-N polypeptide comprises the amino acid sequence of SEQ ID NO: 5, or an amino acid sequence substantially identical thereto. By "substantially identical" is meant sufficient identity to impart the polypeptide with antiviral activity characteristic of a CV-N polypeptide of SEQ ID NO: 5. In this regard, the nucleic acid sequence can encode a CV-N polypeptide comprising an amino acid sequence that has about 50% or greater sequence identity (e.g., about 50% or greater, about 60% or greater, about 70% or greater, about 80% or greater, or about 90% or greater sequence identity) to SEQ ID NO: 5. Preferably, the nucleic acid sequence encodes a CV-N polypeptide that has about 75% or greater sequence identity (e.g., about 75% or greater, about 85% or greater, or about 95% or greater sequence identity) to SEQ ID NO: 5. Desireably, the nucleic acid sequence encodes a CV-N polypeptide that has about 90% or greater sequence identity (e.g., about 95% or greater, about 97% or greater, or about 99% or greater sequence identity) to SEQ ID NO: 5.

[0024] The nucleic acid sequence encoding the CV-N polypeptide can be a genomic or non-genomic sequence. Non-genomic nucleic acid sequences (e.g., cDNA sequences) encoding CV-N are known (see, e.g, U.S. Patents 5,843,882, 6,015,876, and 6,420,336). A genomic nucleic acid sequence encoding the CV-N peptide is provided by the invention described herein, for example, by SEQ ID NO: 3. Other genomic nucleic acid sequences encoding a CV-N polypeptide, such as a genomic nucleic acid sequence obtained from, derived from, or based upon SEQ ID NO: 3 or the genome of any suitable cyanobacterium species that produces CV-N also are considered to be part of the invention and can be used in conjunction with the nucleic acid of the invention. A sequence is "obtained" from a source when it is isolated from that source. A sequence is "derived" from a source when it is isolated from a source but modified in any suitable manner (e.g., by deletion, substitution (mutation), insertion, or other modification to the sequence) so as not to disrupt the normal function of the source gene. A sequence is "based upon" a source when the sequence is a sequence more than about 70% identical (preferably more than about 80% identical, more preferably more than about 90% identical, and most preferably more than about 95% identical) to the source but obtained through synthetic procedures (e.g., polynucleotide synthesis, directed evolution, etc.). Preferably, the genomic nucleic acid sequence encoding CV-N is obtained from the cyanobacterium species Nostoc ellipsosporum, such as the genomic nucleic acid sequence comprises SEQ ID NO: 3. Orthologs and paralogs of the genomic sequence of SEQ ID NO: 3, which was isolated from Nostoc ellipsosporum, can be isolated by using SEQ ID NO: 3, SEQ ID NO: 4, or a fragment thereof in DNA hybridization assays (e.g., Southern Blot).

[0025] In this regard, the invention provides a nucleic acid comprising a genomic nucleic acid sequence encoding a CV-N polypeptide, which genomic nucleic acid sequence can be the nucleic acid sequence of SEQ ID NO: 3, or other genomic acid sequences encoding a CV- N polypeptide as previously described. The nucleic acid comprising a genomic nucleic acid sequence encoding a CV-N polypeptide can further comprise a nucleic acid sequence encoding a signal peptide, including the CV-N signal peptide of the invention or different signal peptides.

[0026] A much preferred nucleic acid of the invention comprises the nucleic acid sequence of SEQ ID NO: 4, wherein the nucleic acid sequence of SEQ ID NO: 4 provides the nucleic acid sequence encoding a CV-N signal peptide (SEQ ID NO: 1) and the genomic nucleic acid sequence encoding a CV-N polypeptide (SEQ ID NO: 3). [0027] The nucleic acid of the invention can further comprise a promoter sequence. To facilitate expression of the genomic nucleic acid sequence within a cell, the nucleic acid sequence encoding the CV-N signal peptide and/or the nucleic acid sequence encoding the target polypeptide (e.g., CV-N polypeptide) preferably are operably linked to (i.e., under the transcriptional control of) one or more promoter and/or enhancer elements. A "promoter" is a DNA sequence that directs the binding of RNA Polymerase and thereby promotes RNA synthesis. A nucleic acid sequence is "operably linked" to a promoter when the promoter is capable of directing transcription of the nucleic acid sequence.

[0028] In general, prokaryotic promoters typically consist of two regions. The RNA polymerase recognition region comprises a consensus sequence of TTGACA (5 'to 3' on the antisense strand), and is located about 35 base pairs upstream of the transcription start site, which is denoted "+1." Thus, the RNA polymerase recognition site is more commonly referred to as the "-35 region." The second region of the prokaryotic promoter consists of the RNA polymerase binding site and comprises a consensus sequence of TATAAT. This region is located about 10 base pairs upstream of the transcription start site, and is also known as the "-10 region" or the "Pribnow Box" (see Maloy et al., eds., Microbial Genetics, 2^nd edition, Jones and Bartlett Publishers, Boston, MA (1994), and Prescott et al., eds., Microbiology, 3^rd edition, Wm. C. Brown Publishers, Dubuque, IA (1996)). [0029] The promoter used in conjunction with the invention can be any suitable promoter. Suitable promoters are known in the art. The promoter preferably is capable of directing transcription in a eukaryotic (desirably mammalian) cell. The promoter can be native (e.g., the native CV-N promoter) or non-native (i.e., heterologous) with respect to the nucleic acid sequence to which it is operably linked. Techniques for operably linking sequences together are well known in the art.

[0030] The functioning of the promoter can be altered by the presence of one or more enhancers and/or silencers present on the vector. "Enhancers" are cis-acting elements of DNA that stimulate or inhibit transcription of adjacent genes. An enhancer that inhibits transcription also is termed a "silencer." Enhancers differ from DNA-binding sites for sequence-specific DNA binding proteins found only in the promoter (which also are termed "promoter elements") in that enhancers can function in either orientation, and over distances of up to several kilobase pairs (kb), even from a position downstream of a transcribed region. [0031] Promoter regions can vary in length and sequence and can further encompass one or more DNA binding sites for sequence-specific DNA binding proteins and/or an enhancer or silencer. Enhancers and/or silencers can similarly be present on a nucleic acid sequence outside of the promoter per se. Desirably, a cellular or viral enhancer, such as the cytomegalovirus (CMV) immediate-early enhancer, is positioned in the proximity of the promoter to enhance promoter activity. In addition, splice acceptor and donor sites can be present on a nucleic acid sequence to enhance transcription.

[0032] Any suitable promoter and/or enhancer sequence can be used in the context of the invention. In this respect, a nucleic acid sequence can be operably linked to a promoter that is native to the sequence (e.g., native to a cyanobacterium), but is located in a non-native position relative to the sequence. Furthermore, the nucleic acid sequence can be operably linked to a cellular promoter, i.e., a promoter that drives expression of a cellular protein. In one aspect, the cellular promoter is preferably a constitutive promoter that works in a variety of cell types. Suitable constitutive promoters are known in the art, and include promoters which drive expression of genes encoding transcription factors, housekeeping genes, or structural genes common to eukaryotic cells (see, e.g., Eukaryotic Promoter Database, as described in Perier et al., Nucleic Acids Res., 28, 302-3 (2000)).

[0033] A viral promoter also can be used. Suitable viral promoters include, for instance, cytomegalovirus (CMV) promoters, such as the CMV immediate-early promoter (described in, for example, U.S. Patents 5,168,062 and 5,385,839), promoters derived from human immunodeficiency virus (HIV), such as the HIV long terminal repeat promoter, Rous sarcoma virus (RSV) promoters, such as the RSV long terminal repeat, mouse mammary tumor virus (MMTV) promoters, HSV promoters, such as the Lap2 promoter or the herpes thymidine kinase promoter (Wagner et al., Proc. Natl. Acad. ScL, 78, 144-145 (1981)), promoters derived from SV40 or Epstein Barr virus, an adeno-associated viral promoter, such as the p5 promoter, and the like.

[0034] Many of the above-described promoters are constitutive promoters. Instead of being a constitutive promoter, the promoter can be a regulatable promoter, i.e., a promoter that is up- and/or down-regulated in response to appropriate signals. In addition, the promoter can be a tissue-specific promoter, i.e., a promoter that is preferentially activated in a given tissue and results in expression of a gene product in the tissue where activated. A tissue-specific promoter suitable for use in the invention can be chosen by the ordinarily skilled artisan based upon the target tissue or cell-type. Preferred tissue-specific promoters for use in the invention are promoters with activity specific to T cells. [0035] The nucleic acids of the invention can be inserted into a vector suitable for delivery to a cell or a host. In this regard, the invention further provides a vector comprising the nucleic acids of the invention as described herein. One of ordinary skill in the art will appreciate that a "vector" is any molecule or composition that has the ability to carry a nucleic acid sequence into a suitable host cell where synthesis of the encoded polypeptide takes place. The vector can be a nucleic acid-based vector or other type of vector. Vectors that are not based on nucleic acids, such as liposomes, are known in the art. Typically and preferably, the vector is a nucleic acid that has been engineered, using recombinant DNA techniques that are known in the art, to incorporate a desired nucleic acid sequence (e.g., a nucleic acid of the invention). Desirably, the vector is comprised of DNA. Examples of suitable DNA-based gene transfer vectors include plasmids and viral vectors. Suitable viral vectors include, for instance, parvoviral-based vectors (i.e., adeno-associated virus (AAV)- based vectors), retroviral vectors, herpes simplex virus (HSV)-based vectors, AAV- adenoviral chimeric vectors, HIV virus-based vectors, and adenovirus-based vectors. The inventive vector can be based on a single type of nucleic acid (e.g., a plasmid) or non-nucleic acid molecule (e.g., a lipid or a polymer). Alternatively, the vector can be a combination of a nucleic acid and a non-nucleic acid (i.e., a "chimeric" vector). For example, a plasmid harboring the nucleic acid can be formulated with a lipid or a polymer as a delivery vehicle. Such a vector is referred to herein as a "plasmid-lipid complex" and a "plasmid-polymer" complex, respectively. The inventive gene transfer vector can be integrated into the host cell genome, or can be present in the host cell in the form of an episome.

[0036] Other aspects of the vector provided by the invention are as described herein with respect to the nucleic acids of the invention.

[0037] The invention further encompasses a polypeptide encoded by a nucleic acid of the invention, as herein described. Accordingly, the invention provides, as a related aspect, an isolated or purified polypeptide comprising a CV-N signal peptide (e.g., an amino acid sequence that has about 50% or greater sequence identity to SEQ ID NO: 2) and, preferably, a target polypeptide such as a CV-N polypeptide. The CV-N signal polypeptide and target polypeptide (e.g., CV-N polypeptide) can be any CV-N signal peptide and any target polypeptide, such as any CV-N signal peptide or target peptide previously described herein. Desirably, the polypeptide of the invention comprises the amino acid sequence of SEQ ID NO: 2. An especially preferred polypeptide comprises the amino acid sequence of SEQ ID NO: 2 and the amino acid sequence of SEQ ID NO: 5. Desirably, the signal peptide sequence (e.g., SEQ ID NO: 2) is at the amino-terminus of the polypeptide.

[0038] The nucleic acids, vectors, and polypeptides of the invention as described herein can be prepared (e.g., isolated or synthesized) using routine methods known in the art, such as those described in, for example, Sambrook et al., Molecular Cloning, a Laboratory Manual, 3^rd edition, Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (2001), Ausubel et al., Current Protocols in Molecular Biology, Greene Publishing Associates and John Wiley & Sons, New York, N.Y. (1994), and Herdewijn, ed., Oligonucleotide Synthesis: Methods and Applications (Methods in Molecular Biology), Humana Press, Totowa, New Jersey (2004). [0039] The invention further provides a cell comprising a nucleic acid or vector of the invention as described herein, wherein the nucleic acid or vector comprises a nucleic acid sequence that is non-native to the cell. [0040] The cell can be any suitable cell that can be transfected with a nucleic acid or vector of the invention and, desirably, maintain the aforementioned nucleic acid or vector, such that the nucleic acid is expressed and the encoded polypeptide (e.g., CV-N) produced in the cell. Preferred cells include bacterial cells. Examples of suitable bacterial cells include lactobacilli, enterococci, E. coli (e.g., E. coli Tb-I, TG-2, DH5α, XL-Blue MRF' (Stratagene), SA2821, and Yl 090), Bacillus subtilis, Salmonella typhimurium, Serratia marcescens, Pseudomonas (e.g., P. aerugenosd), or N. grassa. Alternatively, the bacterial cell can be obtained from a nonpathogenic bacterial strain, such as a nonpathogenic strain of lactobacilli, such as those described by Andreu et al., J. Infect. Diseases, 171, 1237-1243 (1995), especially those having high adherence properties to epithelial cells, such as, for example, adherence to vaginal epithelial cells.

[0041] Plant cells also can be used. The plant cell can be obtained or derived from any suitable plant that is amenable to cell culture and recombinant polypeptide production. Examples of suitable plants include vascular "seeded" plants, such as flowering plants (e.g., lilies), and non-flowering plants (e.g., conifers), and "seedless" plants (e.g., vascular seedless plants and non-vascular seedless plants). A "vascular" plant contains vascular tissues (e.g., xylem and phloem) that transport water and nutrients throughout the plant, and has roots, stems, and leaves. Preferably, the plant cell is obtained from or derived from a seedless plant. Suitable seedless plants include vascular seedless plants, such as whisk ferns (Psilotophyta), club mosses (Lycophyta), horsetails (Sphenophyta), and ferns (Pterophyta), and non-vascular seedless plants, such as Liverworts (Hepatophyta), Mosses (Bryophyta), and Hornworts (Anthocerophyta). Fungal cells also can be used. The cell can be obtained or derived from any suitable fungus, including, for example, mushrooms, molds, yeasts (e.g., S. cerevisiae), and eukaryotic heterotrophs that digest food outside of their bodies. [0042] Of course, the use of animal cells also is within the scope of the invention. Examples of suitable animal cells include insect cells (e.g., Sf9, Ea4), and cells derived from a mammal, including human cell lines. Specific examples of suitable animal cells include VERO, HeLa, 3T3, Chinese hamster ovary (CHO) cells, W138 BHK, COS-7, and MDCK cells.

[0043] The cell can be an isolated cell or the cell can be in a host, such as a bird, plant, or mammal, especially a human.

[0044] Methods of introducing nucleic acids and vectors into isolated cells and the culture and selection of transformed host cells in vitro are known in the art and include the use of calcium chloride-mediated transformation, transduction, conjugation, triparental mating, DEAE, dextran-mediated transfection, infection, membrane fusion with liposomes, high velocity bombardment with DΝA-coated microprojectiles, direct microinjection into single cells, and electroporation (see, e.g., Sambrook et al., supra, Davis et al., Basic Methods in Molecular Biology (1986), and Neumann et al., EMBO J. 1, 841 (1982)). When the cell is in a host, the nucleic acid or vector of the invention can be incorporated into the cell by any suitable method, such as by administering the nucleic acid or vector to the host, wherein the nucleic acid or vector is incorporated into the cell in vivo.

[0045] Desirably, the cell comprising the nucleic acid or vector of the invention expresses a nucleic acid sequence encoding a CV-N signal peptide and/or a target polypeptide (e.g., CV-N polypeptide), such that the nucleic acid sequence is transcribed and translated efficiently by the cell. Preferably, the target polypeptide, such as CV-N polypeptide, is secreted from the cell. Accordingly, the invention provides, as a related aspect, a cell comprising a polypeptide of the invention, wherein the polypeptide is non-native to the cell and comprises a CV-N signal peptide and a target polypeptide. The cell, polypeptide, CV-N signal peptide, and target polypeptide are as described previously herein. Preferably, the polypeptide comprises SEQ ID NO: 2 and SEQ ID NO: 5.

[0046] Other aspects of the cell of the invention are as previously described herein with respect to the nucleic acid, vector, and polypeptide of the invention. [0047] A nucleic acid, vector, polypeptide, or cell of the invention can be used for any purpose. For example, a nucleic acid, vector, or cell of the invention can be used to produce a polypeptide in a cell. A nucleic acid comprising a nucleic acid sequence encoding a CV-N signal peptide and, for example, a target polypeptide can be used to produce the target polypeptide by causing the secretion of the target polypeptide from a cell. In this regard, the invention provides a method of producing a polypeptide, which method comprises contacting a cell with a nucleic acid or vector of the invention, whereupon a polypeptide is produced in the cell and, desirably, excreted from the cell. Any suitable method of contacting the cell with the nucleic acid or vector can be used, and such suitable methods are generally known in the art. The method of producing a polypeptide according to the invention can further comprise the steps of collecting, isolating, and/or purifying the excreted polypeptide. The inventive method of producing a polypeptide can be performed on a small scale, such as may be useful in a laboratory, or on a large scale to produce large quantities of a given polypeptide as may be useful for commercial purposes. Large scale production in accordance with the method of the invention can be facilitated using commercially available equipment and known techniques. Other aspects of the method of producing a polypeptide (e.g., the nucleic acid, polypeptide, vector, cell, etc.) are as previously described herein. Accordingly, any nucleic acid or vector of the invention can be used to produce any polypeptide encoded thereby, which polypeptides also are considered to be part of the invention. The method of producing the polypeptide is especially suitable for producing a CV-N polypeptide, as previously described, in which case it is preferred that the nucleic acid comprise the a nucleic acid sequence encoding a CV-N signal peptide and a nucleic acid sequence encoding a CV-N polypeptide Desirably, the nucleic acid sequence encoding the CV-N polypeptide is a genomic sequence. More preferably, the nucleic acid comprises the nucleic acid sequence of SEQ ID NO: 4.

[0048] The nucleic acid, vector, polypeptide, or cell of the invention also can be used for therapeutic or prophylactic purposes. Accordingly, the invention further provides a method of inhibiting a viral infection in an animal, such as a mammal or human, which method comprises administering to the animal a viral infection-inhibiting amount of the nucleic acid, vector, and/or cell of the invention. A virus is "inhibited" according to the invention if the infectivity or ability of the virus to replicate is reduced to any degree. Thus, the term "inhibition" as used herein encompasses the inhibition of a virus prior to the infection of a host (prophylactic effect) as well as the inhibition of a virus in a host (therapeutic effect). [0049] The inventive method can be used to inhibit any suitable virus which is known in the art to be pathogenic in an animal, such as a mammal or preferably a human. Examples of viruses that may be inhibited in accordance with the present invention include, but are not limited to, Type C and Type D retroviruses, HTLV-I, HTLV-2, HIV, FLV, SIV, MLV, BLV, BIV, equine infectious virus, anemia virus, avian sarcoma viruses, such as Rous sarcoma virus (RSV), hepatitis type A, B, non-A and non-B viruses, arboviruses, varicella viruses, measles, mumps and rubella viruses. The inventive method preferably is used to inhibit infection by retrovirus, more preferably a human immunodeficiency virus (HIV), such as HIV-I and fflV-2.

[0050] The nucleic acid, vector, polypeptide, or cell can be provided to the animal alone, or as a pharmaceutical composition in combination with a pharmaceutically acceptable carrier. Accordingly, in a related aspect, the invention provides a pharmaceutical composition comprising a nucleic acid, vector, polypeptide, and/or cell of the invention, and a pharmaceutically acceptable carrier. By pharmaceutically acceptable is meant a material that is not biologically or otherwise undesirable (i.e., the material can be administered to the animal, along with the nucleic acid, vector, polypeptide, or cell without causing any undesirable biological effects or interacting in a deleterious manner with any of the other components of the pharmaceutical composition in which it is contained). The carrier is selected to minimize any degradation of the nucleic acid, vector, polypeptide, or cell and to minimize any adverse side effects in the animal, as would be well-known to one of ordinary skill in the art.

[0051] One skilled in the art will appreciate that various routes of administering a nucleic acid, vector, polypeptide, or cell are available, and, although more than one route can be used, a particular route can provide a more immediate and more effective reaction than another route. Furthermore, one skilled in the art will appreciate that the particular pharmaceutical carrier employed will depend, in part, upon the particular nucleic acid, vector, polypeptide, or cell employed, and the chosen route of administration. Accordingly, there is a wide variety of suitable formulations for use in the present invention. For example, the pharmaceutical composition can be applied or instilled into body cavities, absorbed through the skin, inhaled, or administered parenterally via, for instance, intramuscular, intravenous, peritoneal, or intraarterial administration.

[0052] Formulations suitable for oral administration include liquid solutions, such as diluents (e.g., water, saline, or fruit juice), capsules, sachets, or tablets, lozenges, pastilles, mouthwashes, solutions or suspensions in an aqueous liquid, oil-in-water emulsions, and water-in-oil emulsions. Tablet formulations can include one or more of lactose, mannitol, corn starch, potato starch, microcrystalline cellulose, acacia, gelatin, colloidal silicon dioxide, croscarmellose sodium, talc, magnesium stearate, stearic acid, and other excipients, colorants, diluents, buffering agents, moistening agents, preservatives, flavoring agents, and pharmacologically compatible carriers. Suitable formulations for oral delivery also can be incorporated into synthetic and natural polymeric microspheres, or other means to protect the nucleic acids or vectors of the invention from degradation within the gastrointestinal tract (see, for example, Wallace et al., Science, 260, 912-915 (1993)).

[0053] The pharmaceutical composition can be administered via inhalation in the form of an aerosol or a microparticulate powder formulation. Aerosol formulations can be placed into pressurized propellants, such as dichlorodifluoromethane, propane, nitrogen and the like. [0054] The pharmaceutical composition can be made into formulations for transdermal application and absorption (see, e.g., Wallace et al., supra). Transdermal electroporation or iontophoresis also can be used to promote and/or control the systemic delivery of the compositions of the invention through the skin (e.g., see Theiss et al., Meth. Find. Exp. Clin. Pharmacol, 13, 353-359 (1991)).

[0055] Formulations suitable for topical administration include, for example, creams, emulsions, gels and the like containing, in addition to the active ingredient, such as, for example, a vector comprising a nucleic acid of the invention . Appropriate carriers for topical formulations are known in the art. Topical administration is preferred for the prophylactic and therapeutic treatment of influenza viral infection, such as through the use of an inhaler, for example.

[0056] Formulations for rectal administration can be presented as a suppository with a suitable base comprising, for example, cocoa butter or a salicylate. Formulations suitable for vaginal administration can be presented as pessaries, tampons, creams, gels, pastes, foams, or spray formulas containing, in addition to the active ingredient, an appropriate carrier. Similarly, the active ingredient, e.g., nucleic acid, vector, polypeptide, or cell, can be combined with a lubricant as a coating on a condom. Indeed, preferably, the active ingredient is applied to any contraceptive device, including, but not limited to, a condom, a diaphragm, a cervical cap, a vaginal ring and a sponge.

[0057] Formulations suitable for parenteral administration include aqueous and nonaqueous isotonic sterile injection solutions, which can contain anti-oxidants, buffers, bacteriostats, and solutes that render the formulation isotonic with the blood of the intended recipient, and aqueous and non-aqueous sterile suspensions that can include suspending agents, solubilizers, thickening agents, stabilizers, and preservatives. The formulations can be presented in unit-dose or multi-dose sealed containers, such as ampules and vials, and can be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example, water, for injections, immediately prior to use. Extemporaneous injection solutions and suspensions can be prepared from sterile powders, granules, and tablets of the kind previously described.

[0058] The pharmaceutical composition can contain other active agents in addition to the inventive nucleic acid, vector, polypeptide, or cell, especially when used to inhibit a virus such as HIV. Representative examples of these additional pharmaceuticals include antiviral compounds, virucides, immunomodulators, immunostimulants, antibiotics and absorption enhancers. Exemplary antiviral compounds include nucleoside/nucleoside reverse transcriptase inhibitors (NRTIs) (e.g., AZT), protease inhibitors (e.g., indinavir), non- nucleoside reverse transcriptase inhibitors (NNRTIs) (e.g., nevirapine) (see Shih et al., PNAS, 88, 9878-9882 (1991)), ddl, ddC, gancylclovir, fiuorinated dideoxynucleosides, TIBO derivatives (e.g., R82913) (see White et al., Antiviral Res., 16, 257-266 (1991)), BI-RJ-70 (see Merigan, Am. J. Med., 90 (Suppl.4A), 8S-17S (1991)), michellamines (see Boyd et al., J. Med. Client., 37, 1740-1745 (1994)) and calanolides (see Kashman et al., J. Med. Chem., 35, 2735-2743 (1992)), nonoxynol-9, gossypol and derivatives, and gramicidin (see Bourinbair et al., Contraception, 49, 131-7 (1994)). Exemplary immunomodulators and immunostimulants include interleukins, soluble CD4 (sCD4), cytokines, antibody preparations, blood transfusions, and cell transfusions. Exemplary antibiotics include antifungal agents, antibacterial agents, and anύ-Pnewnocystitis cαrnii agents. Exemplary absorption enhancers include bile salts and other surfactants, saponins, cyclodextrins, and phospholipids. [0059] It will also be appreciated by one skilled in the art that the nucleic acid or vector, of the invention also can be introduced ex vivo into cells previously removed from a host (e.g., an animal such as a mammal or human), which cells can be re-introduced into the host to express the nucleic acid or vector in vivo. The feasibility of such a therapeutic strategy to deliver a therapeutic amount of an agent in close proximity to desired target cells and pathogens, i.e., HIV and its envelope glycoprotein gpl20, has been demonstrated in studies with cells engineered ex vivo to express a soluble CD4 (see, e.g., Morgan et al., AIDS Research and Human Retroviruses, 10, 1507-1515 (1994)). [0060] The nucleic acid, vector, polypeptide, or cell of the invention also can be used in vitro or ex vivo for virucidal (e.g., HIV) sterilization of an inanimate object or a biological sample, wherein sterilization means the inhibition or removal of a virus to any degree. Inanimate objects include any objects that would benefit from sterilization, such as any object intended for use in research or for administration or implantation in a medical procedure. Inanimate objects include, for example, the surface of an article of laboratory or medical supply or equipment, instrument, device, and the like, including devices and objects intended for surgical implant. Inanimate objects also include a solution, suspension, emulsion, vaccine formulation, or any other fluid material, especially those intended for administration to a patient in a medical procedure. Biological samples include any bodily product such as a fluid (e.g., lymph, blood, a blood component, saliva, mucus, and sperm), cell, tissue, or an organ from an organism or animal, in particular a mammal, such as a human. [0061] According to one aspect of the method, a polypeptide according to the invention can be attached to a solid support matrix to facilitate contacting or binding an infectious virus in a sample. As a more specific example, a CV-N polypeptide can be attached to (e.g., coupled to or immobilized on) a solid support matrix comprising magnetic beads, to facilitate contacting, binding and removal of infectious virus, and to enable magnet-assisted removal of the virus from a sample as described above. Alternatively, and also preferably, the solid support matrix comprises a contraceptive device, such as a condom, a diaphragm, a cervical cap, a vaginal ring or a sponge. Other formulations suitable for in vitro or ex vivo sterilization can be selected or adapted as appropriate by one skilled in the art from any of the aforementioned compositions or formulations. However, suitable formulations for ex vivo or in vitro sterilization or removal of virus from a biological sample or inanimate object are by no means limited to any of the aforementioned formulations or compositions. [0062] Any of the forgoing methods, formulations, or compositions described herein preferably comprises an effective amount of a nucleic acid, vector, polypeptide, or cell of the invention. An "effective amount" or "viral infection-inhibiting amount" of the inventive nucleic acid, vector, polypeptide, or isolated cell is the amount required to produce levels of a CV-N polypeptide sufficient to induce antiviral activity in any given application, or inhibit a viral infection in a mammal. For ex vivo uses, such as virucidal treatments of inanimate objects or biological materials, the amount of the nucleic acid, vector, polypeptide, or isolated cell is preferably such that any virus or virus-producing cells are rendered non-infectious or destroyed. For example, with respect to HIV, this would require that the virus and/or the virus-producing cells be exposed to concentrations of CV-N in the range of 0.1-1000 nM. Similar considerations apply to in vivo applications.

[0063] The following examples further illustrate the invention but, of course, should not be construed as in any way limiting its scope. EXAMPLE 1

[0064] This example illustrates the preparation of a nucleic acid of the invention. [0065] Nostoc ellipsosporum genomic DNA (1 μg) was digested with EcoRV endonuclease, purified using phenol/chloroform extraction, and precipitated with ethanol. 200 ng of the digested DNA was ligated with a T7Notl/Not2 adapter for PCR amplification of upstream and downstream target sequences. The ligation reaction was conducted in a 10 μl volume containing 200 ng of digested genomic DNA, Ix ligation buffer, 20 pmol T7Notl/Not2 adapter, and 5 units of T4 DNA ligase (Sibenzyme, Novosibirsk, Russia). The ligation reaction was allowed to progress overnight at 14 ⁰C and was terminated by a ten minute incubation at 72 ⁰C. The degenerative primers Nosel 1 dir (5' AAGTTCTCTCA(A/G)AC(T/G)TG(T/C)TA(T/C)AA 3') (SEQ ID NO: 6) and Nosel 1 rev (5' TCAATGTTCGC(A/G)AT(A/G)TG(A/G)TC(A/G)TC 3') (SEQ ID NO: 7) were designed and used for PCR amplification of the target DNA fragment. [0066] PCR was performed in a 50 μl reaction containing 10 ng of bacterial genomic DNA, Ix Advantage 2 reaction buffer (BD Biosciences Clontech, Mountain View, CA), 200 μM dNTPs, 0.15 μM Nosel 1 dir primer, 0.15 μM Nosel 1 rev primer, and Ix Advantage 2 Polymerize mix (BD Biosciences Clontech, Mountain View, CA). All PCR reactions were performed on an MJ Research PTC-200 DNA Thermal Cycler. 30 PCR cycles were performed with the following parameters: (i) 5 cycles at 95 ⁰C for 7 seconds; 52 ⁰C for 20 seconds; and 72 ⁰C for 1 minute, and (ii) 25 cycles at 95 ⁰C for 7 seconds; 60 ⁰C for 20 seconds; 72 ⁰C for 1 minute. 2 μl aliquots of the PCR reaction was analyzed using agarose gel-electrophoresis. The PCR fragment was cloned into a Pal 16 vector (plasmid Nosel dir/rev).

[0067] Several gene-specific primers were designed for genome walking to amplify upstream and downstream sequences of the target gene. The sequences of the primers are set forth below in Table 1. Genome walking was performed using a suppression PCR-based method (see Siebert at al., Nucleic Acids Res., 23, 1087-1088 (1995)) and Step-Out PCR (see Matz at al., Nucleic Acids Res., 27, 1558-1560 (1999)).

Table 1

[0068] Each sequence identified by genome walking was further amplified using two separate PCR reactions. The first PCR was performed in a 50 ml reaction volume containing 10 ng bacterial genomic DNA ligate, Ix Advantage 2 reaction buffer (BD Biosciences Clontech, Mountain View, CA), 200 μM dNTPs, 0.15 μM Nost 1 rev primer (upstream sequence) or 0.15 μM Nost 1 dir primer (downstream sequence), Step-out mix (0.015 μM Na21T7 primer and 0.15 μM Na21 primer), and Ix Advantage 2 Polymerize mix (BD Biosciences Clontech, Mountain View, CA). 25 PCR cycles were performed, each having the following parameters: 95 ⁰C for 7 seconds; 64⁰C for 20 seconds; and 72 ⁰C for 1 minute. [0069] For the second PCR, amplification products of the first PCR were diluted 20 times in sterile water. The PCR reaction was carried out in a 50 μl volume containing 1 μl of the diluted first PCR product, Ix Advantage 2 reaction buffer, 200 μM dNTPs, 0.2 μM T7 primer, 0.2 μM Nost2 rev primer (upstream sequence) or 0.2 μM Nost2 dir primer (downstream sequence), and Ix Advantage 2 Polymerize mix. 12 PCR cycles were performed, each having the following parameters: 95 ⁰C for 7 seconds; 64⁰C for 20 seconds; and 72 ⁰C for 1 minute. PCR products were cloned into a Pal 16 vector (to give plasmids Nost downstream and Nost upstream) and sequenced.

[0070] To obtain the complete sequence of the target gene, two novel oligonucleotide primers (Nost F dir and Nost F rev) were designed on the basis of new sequence data and used for PCR amplification of bacterial genomic DNA. This PCR reaction was performed in a 50 ml volume containing: 10 ng bacterial genomic DNA, Ix Advantage 2 reaction buffer, 200 μM dNTPs, 0.15 μM Nost F dir primer, 0.15 μM Nost F rev primer, and Ix Advantage 2 Polymerize mix. 25 PCR cycles were performed, each having the following parameters: 95 ⁰C for 7 seconds; 63 ⁰C for 20 seconds; and 72 ⁰C for 1.5 minutes. The resulting PCR product was cloned into a Pal 16 vector (to give plasmid Nost F dir/rev) and sequenced from both ends.

[0071] DNA sequencing revealed that the complete gene sequence corresponded to SEQ ID NO: 4, a nucleic acid of the invention comprising a genomic nucleic acid sequence encoding a CV-N signal peptide and a genomic nucleic acid sequence encoding a CV-N polypeptide.

[0072] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0073] The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. Any open-ended term (e.g., comprising) used to describe the foregoing invention can be replaced with a closed-ended term (e.g., consisting essentially of, or consisting of) without departing from the spirit and scope of the invention. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. [0074] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

CLAIMS:

1. An isolated or purified nucleic acid comprising a nucleic acid sequence that encodes a CV-N signal peptide, wherein the CV-N signal peptide comprises an amino acid sequence that has about 50% or greater sequence identity to SEQ ID NO: 2.

2. The isolated or purified nucleic acid of claim 1 , wherein the CV-N signal peptide comprises the amino acid sequence of SEQ ID NO: 2.

3. The isolated or purified nucleic acid of claim 2, wherein the nucleic acid sequence that encodes the CV-N signal peptide is SEQ ID NO: 1.

4. The isolated or purified nucleic acid of any of claims 1 -3 further comprising a nucleic acid sequence that encodes a target polypeptide.

5. The isolated or purified nucleic acid of claim 4, wherein the target polypeptide is a cyanovirin-N (CV-N) polypeptide.

6. The isolated or purified nucleic acid of claim 5, wherein the nucleic acid sequence that encodes the CV-N polypeptide is a genomic nucleic acid sequence.

7. The isolated or purified nucleic acid of claim 6, wherein the genomic nucleic acid sequence is SEQ ID NO: 3.

8. The isolated or purified nucleic acid of any of claims 1 -7 comprising the nucleic acid sequence of SEQ ID NO: 4.

9. An isolated or purified nucleic acid comprising a genomic nucleic acid sequence encoding a CV-N polypeptide.

10. The isolated or purified nucleic acid of claim 9, wherein the genomic nucleic acid sequence is SEQ ID NO: 3.

11. A vector comprising the nucleic acid of any of claims 1-10.

12. The vector of claim 11 , wherein the vector is selected from the group consisting of a viral vector, a plasmid, and a liposome.

13. A cell comprising the nucleic acid of any of claims 1 - 10 or the vector of claim 11 or 12, wherein the nucleic acid or vector comprises a nucleic acid sequence that is non- native to the cell.

14. The cell of claim 13, wherein the cell is an isolated cell.

15. The cell of claim 13, wherein the cell is in a host.

16. The cell of claim 15, wherein the host is a mammal.

17. A pharmaceutical composition comprising the nucleic acid of any of claims 1- 10, the vector of claim 11 or 12, or the isolated cell of any of claims 13-16, and a pharmaceutically acceptable carrier.

18. A method of producing a polypeptide, which method comprises contacting a cell with the nucleic acid of any of claims 1-10, the vector of claim 11 or 12, whereupon a polypeptide is produced in the cell.

19. The method of claim 18, wherein the polypeptide is excreted from the cell.

20. A method of inhibiting a viral infection in a mammal, which method comprises administering to a mammal a viral infection-inhibiting amount of the nucleic acid of any of claims 1-10, the vector of claim 11 or 12, or the isolated cell of any of claims 13-16.

21. The method of claim 20, wherein the mammal is a human.

22. The method of claim 20 or 21 , wherein the viral infection is an HIV infection.

23. An isolated or purified polypeptide comprising an amino acid sequence that has about 50% or greater sequence identity to SEQ ID NO: 2.

24. The isolated or purified polypeptide of claim 23 comprising the amino acid sequence of SEQ ID NO: 2.

25. The isolated or purified polypeptide of claim 24 further comprising the amino acid sequence of SEQ ID NO: 5.