Screening of African sera stored for more than 17 years for HIV antibodies by site-directed serology.

Antibodies to Human Immunodeficiency Virus type 1 (HIV-1) and type 2 (HIV-2) were investigated, using site-directed enzyme immunoassay (ELISA), in 320 specimens obtained from three remote, African tribes during 1969-1971. Using HIV-1 E34/E32 ELISA and HIV-2 149 ELISA, assay were conducted on 101 serum specimens from the Korekore tribe of Zimbabwe, 93 specimens from the Mano tribe of Liberia, and 126 specimens from the Turkana tribe of Kenya; specimens which tested positive in ELISA were further tested by radioimmunoprecipitation assay (RIPA) and Western blot (WB). Two serum specimens from the Mano tribe of Liberia gave OD 492 nm values greater than 0.2 in HIV E34/E32 ELISA in all three runs. These two specimens reacted with HIV-1 envelope proteins gp160 and gp120 and the internal protein p24 in RIPA and WB; however, the reactivity was uncostant. All other serum specimens were negative for HIV-1 and HIV-2 antibodies. Site directed ELISA serology for HIV-1 and HIV-2 gave very low rates of false positive reactivity. Thus, reaction with HIV-1 antigen was identified in two persons of one tribe in Liberia in 1971, but HIV-2 antibodies were not detected in this tribe; HIV-1 and HIV-2 antibodies were absent during the late 1960's and early 1970's from two African tribes resident in Zimbabwe and Kenya.