Type-I and type-III HTLV antibodies in hospitalized and out-patient Zairians.

Sera from 182 Zairians (99 females and 83 males), aged 5 to 71 years, including maternity and child care consultants, out-patients suffering from minor injuries and patients hospitalized for tuberculosis, malaria or trauma, were analyzed for specific antibodies to HTLV-I and HTLV-III. Following pre-screening by the ELISA technique, reactive sera were further analyzed for specificity to HTLV-I or HTLV-III antigens by competition and/or Western blotting experiments. African sera, possibly because they have higher immunoglobulin levels than US and European sera, are highly reactive in ELISA systems and confirmatory assays are essential to rule out false-positive results. Confirmed antibody prevalence for HTLV-I was 13.2% (II females and 13 males) and increased with age, suggesting continuous exposure to the virus throughout life. Confirmed antibody prevalence for HTLV-III was 6.0% (8 females and 3 males) and showed a peak age range between 21 and 40 years, suggesting heterosexual transmission. Individuals positive for HTLV-I antibodies were not the same as individuals positive for HTLV-III antibodies, suggesting that infection with one virus did not increase susceptibility to infection by the other virus. Further investigations of the epidemiology and of the immunovirology of HTLV-III in Zaire, in relation to acquired immuno-deficiency syndrome (AIDS)-associated pathologies, should enlighten the question of the significant percentage of HTLV-III-infected individuals who do not manifest symptoms of AIDS.