Structural and Functional Heterogeneity Among Type D Retroviruses

Abstract

Tryptic peptide analysis of major internal structural proteins of six type D retroviruses isolated originally from non human primate species (MPMV, LV, SMRV) or from cultured human cells (HeLaV, HEp2V, PMFV) revealed clear differences among these viruses. The p25 peptide maps of MPMV, LV, PMFC and HEp2V were very similar but showed a striking dissimilarity to the p25 map of HeLaV and the p35 map of SMRV. All viruses could be distinguished by peptide maps of at least two of their three low-molecular-weight proteins plO, pl2, and ppl5. In addition, MPMV and LV contained a minor glycoprotein gp20 that was not detectable in HeLaV, HEp2V and PMFV. This structural diversity correlates in at least one respect with a functional heterogenety. Both intact and disrupted viruses from human cells were able to suppress the response to T-cell mitogens in vitro of lymphocytes from some species, including man, baboon, and rhesus monkey. MPMV, however, was inactive. The suppressive components of high and low molecular weight were identified in PMFV and both were sensitive to heat and proteolytic enzymes. Immunosuppression induced by some type D retroviruses may play an imortant role in immunodeficiency diseases in monkeys and men.