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A comparison of the intracellular precursor polyproteins of simian sarcoma-associated virus [SiSV(SiAV)] and three human virus isolates: HL23V, HEL12V and A1476V.

The intracellular precursor polyproteins of simian sarcoma-simian-associated virus [SiSV(SiAV)] were compared to the intracellular proteins of the human retrovirus isolates. HL23V, HEL12V and A1476V, by radioimmunoprecipitation followed by SDS-polyacrylamide gel electrophoresis and tryptic peptide analysis. Cells infected with SiSV(SiAV) were characterized by polyproteins Pr200gag-pol, gPr80env, Pr80gag, Pr60gag and Pr40gag. Identical intracellular precursor polyprotein profiles were obtained from cells infected with HL23V, HEL12V and A1476V. Tryptic digest mapping of peptides containing [3H]leucine showed the structural composition of Pr60gag to be the virus core proteins, p28, p15/p12 and p10. The SiSV(SiAV) envelope precursor, gPr80env, contained the structural determinants of mature viral gp70 and a non-glycosylated protein termed p15E. The homology of the human isolate viruses, HL23V, HEL12V and A1476V, to the SiSV(SiAV)/GaLV (gibbon ape leukaemia virus) family of viruses was confirmed by mapping studies. Both gPr80env and Pr60gag of SiAV were identical by tryptic peptide mapping to the respective proteins from the three human retrovirus isolates examined. The potential significance of these results to considerations of the origins of SiAV and the SiAV-like human isolates is discussed.