Interrelationship of reverse transcriptases of primate type D retroviruses

Enzyme neutralization experiments by using an antiserum to reverse transcriptase (RT) of Mason-Pfizer monkey virus (MPMV) demonstrated the presence of common antigenic determinants on the RTs of all known type D retroviruses and of determinants discriminating different isolates. The RT of MPMV is antigenically closely related to the RTs of type D viruses isolated from human cell lines although significant differences are also detectable. It shows a lesser degree of relationship to the RTs of squirrel monkey retrovirus (SMRV) and of langur virus (PO-1-Lu). Since the major structural proteins of MPMV and PO-1-Lu are much more related to each other than to the corresponding protein of SMRV it can be concluded that there is no correlation in the degree of relatedness of different proteins of different type D viruses.