At various primate research centers, several macaque species show an acquired immune deficiency syndrome (simian AIDS, SAIDS) characterized by lymphocytopenia, opportunistic infections,and a fibromatosis tumor (RF). Numerous type D retroviruses (designated SAIDS-D/Washington (SAIDS-D/W) have been isolated from several macaque species by cocultivation of tissues and blood with lymphocyte and monolayer cultures. These isolates morphologically transform certain rodent cell lines. The SAIDS-D/W isolates can be distinguished from all other retroviruses by antigenicity and molecular hybridization, including the related type D viruses isolated from the California and New England Primate Centers, as well as Mason-Pfizer monkey virus (MPMV) and langur monkey type D viruses. Six structural proteins from SAIDS-D/W and MPMV have been purified and sequenced; these include the gag proteins p4, p10, p12, p14, p27 and a phosphoprotein designated pp18 for MPMV and pp20 for SAIDS-D/W. The gag proteins of these two viruses are distinct but share a high degree of amino acid sequence homology. The phosphoproteins differ entirely in amino acid composition and molecular weight. The N-terminal portion of SAIDS-D/W pp20 shows an unexpected homology to a 28 residue segment of the env precursor polyprotien of Rous sarcoma virus. Epidemiological studies on approximately 25% of the Washington colony revealed that 57% of the macaques have antibodies to SAIDS-D and 2% to HTLV-I. Twenty animals with RF have SAIDS-D viral sequences in their tumor tissue and SAIDS-D virus has been isolated from all of these animals. Biologically cloned SAIDS-D virus has been inoculated into 19 macaques; four young animals have developed viremia and RF, and another eight animals have developed high antibody titers to various viral proteins. These antibodies neutralize the SAIDS-D virus but not a macaque type C virus. Various antiviral regimens and vaccination protocols are being assessed in an attempt to prevent this disease.
