PubMed1989
Out of 4176 sera from asymptomatic adults originating from Chad, equatorial Guinea and Gabon tested for HIV-1 antibodies, 146 (3.5%) were positive by an enzyme immunoassay (EIA). By Western blot (WB), 20 (0.5%) were positive, i.e. with antibodies to the core and the envelope proteins, 96 (2.3%) were indeterminate, i.e. with antibodies to the viral core proteins only and 30 (0.7%) were negative. On testing for HIV-2 by WB, two of the 96 indeterminate sera had antibodies to the HIV-2 envelope glycoproteins. Two complementary tests were used: a radioimmunoprecipitation assay (RIPA) and a HIV EIA recombinant assay (ENVACOR) to check 53 of these indeterminate sera. Forty-one were positive for the p25 protein in RIPA, of which 34 were negative in ENVACOR; six were positive for core proteins only and one was positive for envelope and core proteins using this assay. Twelve of the 53 indeterminate sera were negative in RIPA, of which 11 were negative and one positive for core proteins in ENVACOR. Thus, 42 of these sera remained indeterminate even after the two additional tests which did not allow a distinction between retroviral infection or non-specific reactions. We were able to isolate an unusual HIV-1 virus from lymphocyte cultures of two subjects presenting antibodies directed only against the core proteins.