Unique pattern of HTLV-III (AIDS-related) antigen recognition by sera from African children in Uganda (1972)

Of 75 sera collected in the West Nile district of Uganda over a 1-year period between 1972 and 1973, 50 (66%) had antibody reactivity to human T-cell lymphotropic virus subgroup III (HTLV-III) at low titer levels. Sera were initially screened by HTLV-III enzyme linked immunosorbent assay and sera with values less than normal mean + 2 SD were removed from testing. The remaining sera were tested for positivity by an amplified Western blotting procedure which incorporated a three-layer immunoperoxidase procedure. Immunoglobulin reactive with HTLV-III Mr 24,000, 41,000, and 76,000 proteins were present in nearly all positive sera. The antibody status of this group was unlike any normal or acquired immunodeficiency syndrome-risk group previously tested. The high prevalence and relatively low titers suggest the detection as early as 1972 of a relative or predecessor of HTLV-III or of HTLV-III itself but existing in a population acclimated to its presence. It further suggests a likely African origin of HTLV-III.