Serum Antibodies to Human T-cell Leukaemia Virus Type I in Different Ethnic Groups and in Non-human Primates in South Africa

The prevalence of humoral antibodies to human T-cell leukaemia virus type I (HTLV-I) was investigated in different ethnic groups and in non-human primates in South Africa. Serum antibody levels were determined by enzyme-linked immunosorbent assay (ELISA) using either disrupted whole HTLV-I or purified p24 core protein (p24 HTLV-I) as antigens. ELISA was complemented by direct radio-immunoprecipitation assays using either purified iodinated p24 HTLV-I or radiolabelled lysates of an HTLV-producing cell line as antigen followed by sodium dodecyl sulphate polyacrylamide gel electrophoresis of the immunoprecipitates, and by immunofluorescence using the HTLV-I-producing cell line HUT-102 as antigen. Antibodies were demonstrated in 3,5% of Asians, 3,5% of blacks and 4,1% of coloureds, but not in whites, and also in 29% of vervet monkeys and 33% of baboons. We conclude that HTLV-I or closely related viruses cause widespread infection in non-human primates in South Africa and in a lower percentage of humans, including apparently healthy blood donors. We are currently isolating retroviruses from seropositive reactors and investigating the possible relevance to disease in South Africa.