Abstract

PIP: The AIDS epidemic has spread to central and eastern Africa, however in western Africa it appears to have spread very little, if at all. A study was conducted on 569 adult Senegalese subjects at risk for AIDS to determine the prevalence of infection. AIDS was detected by enzyme linked immunosorbent assay, with confirmation by Western blot. The methods used are described in detail. The seropositivity rates were 5% in prostitutes, 1.2% in patients with tuberculosis, and 0.8% in the controls. 2% of samples from prostitutes were negative on ELISA but positive on Western blot and radioimmunoprecipitation assay (RIPA), illustrating the danger of false negatives. In HIV positive Senegalese patients, there was a noted absence of antibodies to the gp41 glycoprotein. These same subjects had antibodies against the gp32 protein of STLV III/Agm, a simian retrovirus; such antibodies are absent from HIV positive subjects from central Africa and America. The antibody profile in Senegalese subjects was the same as in simian control serum. This is indicative of a new HTLV IV virus similar to the STLV III/Agm virus. Virus was isolated from lymphocytes of subjects and was found on electron microscopy to have a dense cylindrical core similar to STLV III/Agm. This virus could not be isolated from seronegative subjects. This new virus was isolated from subjects who were apparently in good health. No evidence of illness could be detected by clinical, biological and immunological examination. It appears that this virus is not pathogenic. The HTLV-IV virus may be protective against HTLV-III infection, thus accounting for the low incidence of HTLV-III infection in Western Africa.