Serological Characterization of HTLV-III Infection in AIDS and Related Disorders

Current efforts to test blood donors and other persons for exposure to the human T cell lymphotropic virus type III (HTLV-III), the etiologic agent of the acquired immunodeficiency syndrome (AIDS), are based on the measurement of serum antibodies to viral antigens. We studied presence of serum antibodies to HTLV-III-related antigens from 767 individuals with AIDS or AIDS-related complex (ARC) or asymptomatic persons at risk for AIDS by using ELISA and immunoblot techniques. Of the 280 specimens from AIDS and ARC subjects that were tested, 99% were ELISA reactive and 96% were immunoblot reactive. Greater than 96% of the seropositive subjects manifested antibodies to the p24 core antigen, whereas only 88% had antibodies to the gp41 envelope-related glycoprotein. Contrary to previous reports, a short incubation time in the immunoblot assay failed to detect low-titer or low-affinity antibodies that were detected by overnight incubation. There was no apparent difference in pattern of antibodies to HTLV-III-related antigens in symptomatic vs. asymptomatic seropositive individuals.