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

Abstract

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.

PIP: Sera from 75 children from an isolated subsistence farming region of the Ugandan Nile valley in 1972-1973 showed a unique pattern of antibody titer to HTLV-III: a high prevalence but low titer for a limited number of viral proteins. The sera were originally collected at random as controls for a study of Burkitt's lymphoma. Mean age was 6.4 years. Sera were tested quantitatively by ELISA and 50 of 55 positives were confirmed by Western blot. The most prominent bands had molecular weights of 76,000, 41,000 and 24,000, coinciding with HTLV-III antigens previously described. The geometric mean titer was 295 with a range of 100-1000. The results suggest high prevalence of a closely related virus in this population.