Biochemical studies of primate retroviruses.

In the present paper, recent biochemical studies of retroviruses carried out in our laboratory are summarized. Protein compositions, peptide maps of internal structural proteins, neighborhoods of major structural proteins, and serological properties of reverse transcriptases of type D virus isolates from human cells (including Graffi's isolate termed PMFV and also isolates from HeLa- and HEp-2 cells) were compared with those of type D viruses from Old World (Mason-Pfizer virus of rhesus monkeys, langur virus) and New World (squirrel monkey retrovirus) monkeys. The results provide various new informations on, and further demonstrate the diversity of primate type D viruses. Other studies showed that tumor promoting agents (phorbol ester TPA, indole alkaloid teleocidin) are able to considerably increase, in a transient manner, the production of type C and type D primate retroviruses in persistently infected human cells. From experiments demonstrating a disintegrating activity of chelating agents (EDTA, EGTA) and certain psychoactive drugs (including trifluoperazine) on various primate and nonprimate retroviruses it is concluded that divalent cations, probably Ca2+ ions, and possibly also cation-binding proteins are associated with retroviral membranes and that complexing of these components results in loss of viral infectivity.