HIGHLY ENDEMIC HUMAN T-LYMPHOTROPIC VIRUS TYPE-II (HTLV-II) INFECTIONIN A VENEZUELAN-GUAHIBO-AMERINDIAN GROUP

Sera from 166 Guahibo Indians (55% of the population) living in southw est Venezuela were screened by enzyme-linked immunoassay for antibodie s to human T-cell lymphotropic virus (HTLV) I and II. Positive samples were confirmed by immunofluorescence and Western blot. Forty-one Guah ibos (24.8%) were found to be seropositive. Polymerase chain reaction (PCR) analysis of proviral DNA in mononuclear cell lysates revealed th e virus to be HTLV-II. Prevalence increased with age, and sexual conta ct with HTLV-II-seropositive partners was identified as a risk factor for infection. PCR amplification of a region of the pol gene, utilizin g the primer pair SK110/SK111, with subsequent digestion of the 140-ba se-pair amplification products with HinfI and MseI restriction enzymes , showed an HTLV-II subtype-b restriction pat tern in all cases. These data suggest that the substrain infecting this Guahibo community belo ngs to the b subtype, the most frequent among Paleo-Amerindian populat ions.