Overt and latent HIV 1 and HTLV-I infection in cohorts of at high risk individuals in Argentina

We conducted a survey using serology and polymerase chain reaction assays to detect HIV 1 and/or HTLV-I antibodies and viral DNA, respectively, in 113 intravenous drug abusers and in 62 sexually active high risk individuals attending two Drug Addict Centres and a Centre for Venereal Diseases in Buenos Aires, Argentina. At the time of the survey 137 of these subjects were known to be HIV 1 seropositive but none of them was symptomatic. Serological tests for HTLV-I were found to be positive in 38 (21·7%) of the HIV1 positive individuals, whereas all of the 38 HIV 1 seronegative subjects were also seronegative for HTLV-I antibodies. Cene amplification assays carried out in blood sample DNA from the 38 HIV 1/HTLV-I seronegative individuals, revealed HIV1 DNA in six out of 28 intravenous drug abusers (21·5%). One subject (2·6%) was positive for both HIV 1 and HTLV-I DNA sequences, whereas four (10·5%) showed HTLV-I DNA only. To determine whether these individuals were infected with HTLV-I and/or HTLV-II, DNA samples were also amplified with HTLV-II specific primers and no evidence of HTLV-II infection was observed. None of the subjects seroconverted according to conventional serological tests during the 2 year follow-up period. The 10 seronegative subjects belonging to the sexual risk group were negative for both HIV1 and HTLV-I in polymerase chain reaction assays. We conclude that not only HIV 1, but also HTLV-I is a widely spread infection in intravenous drug abusers and sexually active high risk individuals in Argentina. The latter included homosexual and heterosexual males, and females with promiscuous behaviour or partners to HIV1 infected individuals. In addition, our data show that in the high risk HIV 1/HTLV-I seronegative population of intravenous drug abusers, some of them may show a dormant HIV 1 and/or HTLV-I infection, this latter being a virtually sporadic finding reported so far. The biological reasons for this latency and its possible implication are important issues that need to be further evaluated.