Comparative analysis: intracellular precursor polyproteins of baboon endogenous retroviruses and human viral isolate HL23V

S A Whiteley, R B Naso
1981 Journal of Virology  
Intracellular precursor polyproteins of three baboon endogenous retrovirus (BaEV) isolates, m7, 455K, and BILN, were compared with the intracellular proteins of the type C human isolate HL23V by radioimmunoprecipitation, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and tryptic peptide analysis. Human and canine cells infected with m7-BaEV and canine thymus cells infected with BILN-BaEV were characterized by identical precursor polyproteins Pr85V", Pr70-719"9, Pr659"9,
more » ... 0-719"9, Pr659"9, and gPr85env. Canine cells infected with 455K-BaEV consistently showed a slightly different pattern of precursor polyproteins. These included Pr85V", Pr7O9'9, Pr67gag, and gPr85env. By tryptic digest mapping of peptides containing [3H]leucine, m7-BaEV and 455K-BaEV were shown to be highly related. By comparison, mapping studies showed that BILN-BaEV was less highly related to m7-BaEV than was 455K-BaEV. Differences in these related BaEV isolates presumably reflected virus-specific differential cleavage of core protein precursors or alterations in polyprotein primary structure or both. Chase-incubated cells infected with BaEV also contained a stable, p28related polyprotein termed P72r". This polyprotein migrated upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis slightly slower than the major core protein precursor Pr70-719'9 and appeared to arise by posttranslational modification of Pr7O-719'9. Immunoprecipitation of extracts of HL23V-infected cells with antisera to simian sarcoma-simian-associated virus proteins and BaEV proteins confirmed that these cells contained two unrelated viral components, one that was similar to m7-BaEV or BILN-BaEV and a second that was related to simian sarcoma-simian-associated virus. Tryptic digest mapping of BaEV and HL23V precursor polyproteins suggested that the BaEV-like component of HL23V was more closely related to m7-BaEV than to 455K-BaEV or BILN-BaEV.
doi:10.1128/jvi.37.3.860-870.1981 fatcat:ctsf6ir2jza4jeb2hvvzsf63wq