Background

HTLV-IIb is endemic among aborigines in the northeast region of Argentina. HTLV-II is also present in IDUs and, in Argentina, only one case has been previously characterized as subtype IIa.

Materials and methods

A nested-PCR for LTR of HTLV-II was performed in 11 IDUs HTLV-II seropositive from Buenos Aires city from 2000 to 2001. Neighbor-joining and Parsimony trees were carried out using Phylip package program.

Results

Ten of the samples clustered with the HTLV. IIb subgroup while 1 of the samples grouped with the IIa subgroup closer to Brazilian aborigine isolates (Kay139, Kay73 and BRAZ.A21). All individuals were also co-infected with HIV-1.

Conclusion

These results correlate with previous studies conducted among IDUs from New York city, Vietnam and Southern Europe where HTLV-IIb was more frequently found. In contrast, IIa is found among IDUs from other regions of the USA, Europe and Brazil. This is the first time in which subtype b is described in Argentina among IDUs. Its presence may be due to migrations of aborigines to big cities and the introduction of drugs in this population. Lately, there was also a high rate of migration and tourism to Argentina, especially from southern Europe and USA, possibly contributing to the spread of HTLV-IIb in our country. Interestingly, the IIa sample described here was found to be related with Brazilian aborigine sequences in contrast to the previous Argentinian IDU which was closer to African isolates.