Submergence-induced protein-like factors

Abstract

A pure polypeptide containing an amino acid sequence at least 80% identical to SEQ ID NO:5. The polypeptide, when expressed in a cell, increases susceptibility of the cell to hepatitis C virus infection.

What is claimed is:  
     
         1 . A pure polypeptide comprising an amino acid sequence at least 80% identical to SEQ ID NO:5, wherein the polypeptide, when expressed in a cell, increases susceptibility of the cell to hepatitis C virus infection.  
     
     
         2 . The polypeptide of  claim 1 , wherein the amino acid sequence is at least 85% identical to SEQ ID NO:5.  
     
     
         3 . The polypeptide of  claim 2 , wherein the amino acid sequence is at least 90% identical to SEQ ID NO:5.  
     
     
         4 . The polypeptide of  claim 3 , wherein the amino acid sequence is at least 95% identical to SEQ ID NO:5.  
     
     
         5 . The polypeptide of  claim 4 , wherein the amino acid sequence is SEQ ID NO:5.  
     
     
         6 . An isolated nucleic acid encoding the polypeptide of  claim 1 , or a complementary sequence thereof.  
     
     
         7 . The nucleic acid of  claim 6 , wherein the amino acid sequence is at least 85% identical to SEQ ID NO:5.  
     
     
         8 . The nucleic acid of  claim 7 , wherein the amino acid sequence is at least 90% identical to SEQ ID NO:5.  
     
     
         9 . The nucleic acid of  claim 8 , wherein the amino acid sequence is at least 95% identical to SEQ ID NO:5.  
     
     
         10 . The nucleic acid of  claim 9 , wherein the amino acid sequence is SEQ ID NO:5.  
     
     
         11 . The nucleic acid of  claim 10 , wherein the nucleic acid is SEQ ID NO:3, 6, 7, or 8, or a complementary sequence thereof.  
     
     
         12 . An isolated nucleic acid characterized in that it hybridizes under stringent conditions to SEQ ID NO:1, or a complementary sequence thereof.  
     
     
         13 . An antibody against the polypeptide of SEQ ID NO:5.  
     
     
         14 . A cell comprising a nucleic acid of  claim 6 , wherein the cell expresses the nucleic acid.  
     
     
         15 . The cell of  claim 14 , wherein the cell is a liver cell.  
     
     
         16 . The cell of  claim 14 , wherein the cell also expresses an Epstein-Barr nuclear antigen-1 gene.  
     
     
         17 . The cell of  claim 16 , wherein the cell is a liver cell.  
     
     
         18 . A method of expressing a transcript in a cell, the method comprising: 
 introducing a vector into a cell, the vector containing a nucleic acid encoding a transcript; and    expressing the transcript in the cell;    wherein the transcript is characterized in that it hybridizes under stringent conditions to SEQ ID NO:1, or a complementary sequence thereof.    
     
     
         19 . The method of  claim 18 , wherein the transcript encodes the polypeptide of  claim 1 .  
     
     
         20 . The method of  claim 19 , wherein the cell is a liver cell.  
     
     
         21 . A method of producing hepatitis C viruses, the method comprising infecting a cell of  claim 14  with a hepatitis C virus and allowing the virus to replicate in the cell.  
     
     
         22 . The method of  claim 21 , wherein the cell is a liver cell.  
     
     
         23 . The method of  claim 21 , wherein the cell also expresses an Epstein-Barr nuclear antigen-1 gene.  
     
     
         24 . The method of  claim 23 , wherein the cell is a liver cell.  
     
     
         25 . A method of determining susceptibility of a cell to hepatitis C virus infection, the method comprising determining a Sip-L expression level in a cell, wherein the Sip-L expression level in the cell, if higher than that in a normal cell, indicates that the cell is more susceptible to hepatitis C virus infection.  
     
     
         26 . The method of  claim 25 , wherein the cell is a liver cell.  
     
     
         27 . A method of identifying a compound for modulating susceptibility of a cell to hepatitis C virus infection, the method comprising: 
 contacting a compound with a cell expressing a Sip-L gene, and    determining a Sip-L expression level in the cell,    wherein the Sip-L expression level in the presence of the compound, if different from that in the absence of the compound, indicates that the compound is a candidate for modulating susceptibility of a cell to hepatitis C virus infection.    
     
     
         28 . The method of  claim 27 , wherein the cell is a liver cell.  
     
     
         29 . The method of  claim 27 , wherein the cell also expresses an Epstein-Barr antigen-1 gene.  
     
     
         30 . The method of  claim 29 , wherein the cell is a liver cell.  
     
     
         31 . A method of producing a compound for modulating susceptibility of a cell to hepatitis C virus infection, the method comprising: 
 contacting a compound with a cell expressing a Sip-L gene;    determining a Sip-L expression level in the cell, the Sip-L expression level in the presence of the compound, if different from that in the absence of the compound, indicating that the compound is a candidate for modulating susceptibility of a cell to hepatitis C virus infection; and    producing the compound.    
     
     
         32 . A method of determining whether a subject is suffering from or at risk for developing liver cancer, the method comprising: 
 providing a sample from a subject, the sample containing an eSip-L gene product; and    determining an eSip-L expression level in the sample;    wherein the eSip-L expression level in the sample, if higher than that in a sample from a normal subject, indicates that the subject is suffering from or at risk for developing liver cancer.    
     
     
         33 . The method of  claim 32 , wherein the sample is a liver tissue sample.  
     
     
         34 . A method of identifying a compound for treating liver cancer, the method comprising: 
 contacting a compound with a cell expressing an eSip-L gene, and    determining an eSip-L expression level in the cell,    wherein the eSip-L expression level in the presence of the compound, if lower than that in the absence of the compound, indicates that the compound is a candidate for treating liver cancer.    
     
     
         35 . The method of  claim 34 , wherein the cell is a liver cell.  
     
     
         36 . A method of producing a compound for treating liver cancer, the method comprising: 
 contacting a compound with a cell expressing an eSip-L gene;    determining an eSip-L expression level in the cell, the eSip-L expression level in the presence of the compound, if lower than that in the absence of the compound, indicating that the compound is a candidate for treating liver cancer; and    producing the compound.    
     
     
         37 . A method of treating liver cancer, the method comprising: 
 identifying a subject suffering from or being at risk for developing liver cancer, and    administering to the subject a composition to decrease an eSip-L level in the subject.    
     
     
         38 . The method of  claim 37 , wherein the composition is administered into a liver cell.  
     
     
         39 . The method of  claim 37 , wherein the composition includes a nucleic acid encoding a transcript, the transcript being characterized in that it hybridizes under stringent conditions to the sense strand of an eSip-L gene.  
     
     
         40 . The method of  claim 39 , wherein the composition is administered into a liver cell.  
     
     
         41 . A pharmaceutical composition comprising a pharmaceutically acceptable carrier and a nucleic acid encoding a transcript, wherein the transcript is characterized in that it hybridizes under stringent conditions to the sense strand of an eSip-L gene.