High rate of human T lymphotropic virus type IIa infection in HIV type 1-infected intravenous drug abusers in Ireland

Serological and molecular analyses of a cohort of HIV-1-infected intravenou s drug abusers (IVDAs) (n = 103) in Dublin, Ireland have demonstrated that 15 of 103 (14.6%) were infected with HTLV-II, which is the highest infectio n rate yet recorded for any European country. Restriction fragment length p olymorphism (RFLP) analysis of the env region of the provirus demonstrated that the infection involved only the HTLV-IIa subtype; the HTLV-IIb subtype was not detected. Phylogenetic analysis of the nucleotide sequences of the long terminal repeat (LTR) confirmed infection with the HTLV-IIa subtype, and demonstrated that the viruses clustered closely with HTLV-IIa isolates from North American IVDAs, Previous observations that IVDAs in southern Eur ope, specifically Spain and Italy, appear to be infected predominantly with the HTLV-IIb, subtype, along with the present report and evidence that IVD As in Sweden are infected with the HTLV-IIa subtype, suggest different orig ins of HTLV-II infection in Europe.