Methods and compositions for modulating the interaction between the APJ receptor and the HIV virus

Abstract

The orphan seven transmembrane domain receptor, APJ, can function as a coreceptor for cellular infection by the HIV virus. The establishment of cell lines that coexpress CD4 and APJ provide valuable tools for continuing research on HIV infection and the development of anti-HIV therapeutics.

What is claimed is:  
     
         1 . A recombinant eukaryotic cell transformed with a polynucleotide encoding an APJ polypeptide or a polynucleotide encoding a CD4 polypeptide, wherein the cell coexpresses APJ and CD4 polypeptides.  
     
     
         2 . A recombinant eukaryotic cell transformed with a polynucleotide encoding an APJ polypeptide and a polynucleotide encoding a CD4 polypeptide, wherein the cell coexpresses APJ and CD4 polypeptides.  
     
     
         3 . A recombinant eukaryotic cell according to  claim 1 , wherein the cell is stably transformed.  
     
     
         4 . A recombinant eukaryotic cell according to  claim 2 , wherein the cell is stably transformed both polynucleotides.  
     
     
         5 . The cell as in any of claims  1 - 4 , wherein the cell is a human cell.  
     
     
         6 . The cell as in any of claims  1 - 4 , wherein the cell is a non-human cell.  
     
     
         7 . An antibody which specifically binds to an extracellular domain of APJ, wherein the antibody inhibits HIV infection of a target cell that coexpresses APJ and CD4 polypeptides.  
     
     
         8 . An antibody which specifically binds to an extracellular domain of APJ, wherein the antibody inhibits membrane fusion between a first cell coexpressing APJ and CD4 polypeptides and second cell expressing an HIV env protein.  
     
     
         9 . An antibody according to  claim 7  or  8 , wherein the antibody is a monoclonal antibody.  
     
     
         10 . An antibody according to  claim 9 , wherein the antibody recognizes an epitope comprising an amino acid sequence corresponding to a portion of the first extracellular domain of APJ.  
     
     
         11 . An antibody according to  claim 10 , wherein the amino acid sequence corresponding to a portion of the first extracellular domain of APJ comprises the amino acid sequence Asn-Tyr-Tyr-Gly (SEQ ID NO: 3).  
     
     
         12 . An antibody according to  claim 9 , wherein the antibody recognizes an epitope comprising an amino acid sequence corresponding to a portion of the second extracellular domain of APJ.  
     
     
         13 . A substantially purified peptide fragment of APJ, wherein the peptide inhibits HIV infection of a target cell that coexpresses APJ and CD4 polypeptides.  
     
     
         14 . A substantially purified peptide fragment of APJ, wherein the peptide inhibits cell fusion between a first cell coexpressing APJ and CD4 polypeptides and a second cell expressing an HIV env protein.  
     
     
         15 . A substantially purified peptide fragment of APJ according to  claim 13  or  14 , wherein the peptide fragment comprises an amino acid sequence corresponding to a portion of the first extracellular domain of APJ.  
     
     
         16 . A substantially purified peptide fragment of APJ according to  claim 15 , wherein the amino acid sequence corresponding to a portion of the first extracellular domain of APJ comprises the amino acid sequence Asn-Tyr-Tyr-Gly (SEQ ID NO:3).  
     
     
         17 . A substantially purified peptide fragment of APJ according to  claim 13  or  14 , wherein the peptide fragment comprises an amino acid sequence corresponding to a portion of the second extracellular domain of APJ.  
     
     
         18 . A method for identifying a compound that modulates interaction between an HIV virus and an APJ receptor comprising incubating a first cell line which coexpresses CD4 and APJ polypeptides with a second cell line which expresses an env protein under conditions which promote cell fusion, in the presence and absence of a test compound, and determining whether the presence of the test compound inhibits cell fusion between the first cell line and the second cell line.  
     
     
         19 . A method according to  claim 18 , wherein cell fusion is determined by detection of a reporter molecule.  
     
     
         20 . A method according to  claim 19 , wherein the reporter molecule is selected from the group consisting of a radioisotope, a fluorescent compound, a bioluminescent compound, a chemiluminescent compound, a metal chelator, or an enzyme.  
     
     
         21 . A method according to  claim 19  wherein the reporter molecule is B-galactosidase or luciferase.  
     
     
         22 . A method for identifying a compound that modulates interaction between an HIV virus and an APJ receptor comprising incubating a cell line which expresses CD4 and APJ polypeptides with a test virus carrying an env protein, in the presence and absence of a test compound, and determining whether the presence of the test compound inhibits infection of the cell line by the test virus.  
     
     
         23 . A method according to  claim 22 , wherein infection is determined by detection of a reporter molecule.  
     
     
         24 . A method according to  claim 23 , wherein the reporter molecule is selected from the group consisting of a radioisotope, a fluorescent compound, a bioluminescent compound, a chemiluminescent compound, a metal chelator, or an enzyme.  
     
     
         25 . A method according to  claim 23 , wherein the reporter molecule is B-galactosidase or luciferase.  
     
     
         26 . A method of inhibiting HIV infection of a target cell expressing an APJ and CD4 polypeptides comprising contacting the target cell with an effective amount of a APJ binding or blocking agent.  
     
     
         27 . The method of  claim 26 , wherein the agent is an anti-APJ antibody or epitope binding fragment thereof.  
     
     
         28 . The method of  claim 27 , wherein the antibody is a monoclonal antibody or a polyclonal antibody.  
     
     
         29 . The method of  claim 26 , wherein said contacting is accomplished by in vivo administration to a subject.  
     
     
         30 . The method of  claim 26 , wherein the agent is a peptide fragment of APJ.  
     
     
         31 . A method of treating a subject having an HIV-related disorder associated with expression of APJ comprising administering an agent that suppresses APJ to the subject.  
     
     
         32 . The method of  claim 31 , wherein the agent is an anti-APJ antibody.  
     
     
         33 . The method of  claim 31 , wherein the agent is an antisense polynucleotide that hybridizes to an APJ polynucleotide.  
     
     
         34 . The method of  claim 31 , wherein the agent is introduced into a cell using a carrier.  
     
     
         35 . The method of  claim 34 , wherein the carrier is a vector.  
     
     
         36 . A method of treating a subject having or at risk of having an HIV infection or related disorder, comprising administering a therapeutically effective amount of an anti-APJ antibody or a peptide fragment to the subject.  
     
     
         37 . A method according to  claim 36 , wherein the subject is a fetus.  
     
     
         38 . A transgenic non-human animal having a phenotype characterized by expression of APJ polypeptide and CD4 polypeptide otherwise not naturally occurring in the animal, wherein the phenotype is conferred by a transgene contained in the somatic cells and germ cells of the animal, and wherein the transgene comprises a polynucleotide encoding an APJ polypeptide and a polynucleotide encoding a CD4 polypeptide.