ABSTRACT
Serum samples from 460 patients with existing or previous Plasmodium infections, high antimalarial antibody titres, and no apparent risk of exposure to human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) were assayed for HTLV-III/LAV antibody; only 1 sample, from a 21-year-old African woman, was strongly reactive by enzyme-linked immunosorbent assay (ELISA) and positive by western blot. Conversely, no sample from 100 HTLV-III/LAV-positive American homosexual men was strongly reactive for antibodies to the four Plasmodium species that infect human beings by an indirect fluorescent antibody technique, or for antibodies to Plasmodium falciparum by an ELISA technique. Thus, exposure to Plasmodium does not result in HTLV-III/LAV seropositivity, and HTLV-III/LAV antibodies are not strongly cross-reactive with malarial antigens.