Inapparent carriers of simian acquired immune deficiency syndrome type D retrovirus and disease transmission with saliva.

Simian acquired immune deficiency syndrome (SAIDS) type D retrovirus (SRV) was isolated from saliva, urine, and peripheral blood mononuclear cells of a 6-year-old healthy rhesus monkey (Macaca mulatta) seronegative for antibodies to human T-lymphotropic virus (HTLV) type I, HTLV type III, and simian T-lymphotropic virus type III (STLV-III), identified as an inapparent SAIDS carrier in retrospective epidemiologic studies. This animal was linked to 34 cases of SAIDS over a 3-year period. Two juvenile rhesus monkeys inoculated iv with the SRV-containing saliva from this carrier became persistently infected with the retrovirus and developed SAIDS after 4-6 weeks. Both animals seroconverted to SRV, but neither had detectable preinoculation or postinoculation antibodies against HTLV type I, HTLV type III, or STLV-III. One of these animals died of SAIDS with disseminated cytomegalovirus infection after 24 weeks, and the other remains alive with persistent SRV viremia, generalized lymphadenopathy, and splenomegaly after a transient immunosuppression. Major clinical and pathological features associated with the newly described STLV-III were not observed. SRV was subsequently identified in saliva of 2 additional healthy carriers as well as monkeys with SAIDS. The findings of a carrier state in SAIDS and evidence for saliva transmission of the probable causative virus further support the usefulness of this animal model of nononcogenic immunosuppressive retroviral disease.