Molecular epidemiology of HTLV-2 infection among intravenous drug users in Spain.

BACKGROUND

HTLV-2 infection is prevalent among intravenous drug users (IDUs), which often are coinfected with HIV-1. Two main subtypes, HTLV-2a and -2b, have been described among European IDUs, with a characteristically geographic distribution: IIa in northern Europe and IIb in the south. Although frequent traveling within Europe might have favoured a wide dissemination of diverse HTLV-2 variants, HTLV-2b was so far the only subtype reported in Spain.

OBJECTIVE

To investigate the current molecular epidemiology of HTLV-2 in Spain.

STUDY DESIGN

Twenty-six new HTLV-2 strains isolated from IDUs over the last 11 years in different geographic regions were examined. The HTLV LTR region (620bp) was sequenced and phylogenetic analyses were performed. Endonuclease restriction sites were examined to further characterize the HTLV-2 subgroup.

RESULTS

All 26 individuals infected with HTLV-2 showed viruses belonging to the HTLV-2 b4 clade and were closely related to the previously reported HTLV-2 Spanish and Italian IDU isolates.

CONCLUSIONS

HTLV-2 subtype b4 continues to be the only HTLV-2 subgroup recognized so far in Spain and no introduction of other HTLV-2 variants has occurred over the last 11 years.