[Isolation, sequencing and ultrastructure of HTLV-I and HTLV-II retroviruses. Presence of the HTLV-II subtype b among Spanish intravenous drug addicts].

BACKGROUND: Six cases of HTLV-I/II infection were selected for isolation and characterization of these retrovirus. METHODS: Detection of anti-HTLV antibodies was carried out by enzyme immunoassay (EIA), immunofluorescence (IFI), and Western blot (WB). Analysis of proviral DNA was performed by PCR. Viral culture and partial sequencing of the pol and pX genes were carried out. Electron microscopy morphologically characterized the viral particles. RESULTS: Serologic study demonstrated four cases of HTLV-II, one of HTLV-I, and one non-typeable HTLV infections. This last case was confirmed as positive for HTLV-II by PCR. Five new HTLV-II and one HTLV-I infected cell lines have been established by co-culture. Electron microscopy allowed morphologic characterization of the viral particles found in the infected cells. The sequence of the five strains of HTLV-II was identical demonstrating a divergence of 0.49% in the pX region and of 4.5% in the pol region compared with the HTLV-II Mo prototype. Comparison of these sequences with those corresponding to different strains of HTLV-II isolates from American Indians (subtypes b) suggest that these Spanish strains are more closely related with the subtype b than with the subtype a (HTLV-II Mo). Genetic variability study did not reveal any change in the sequence of these stains suggesting that the variability of these retroviruses in very infrequent in the regions studied. The analysis of the pol region of the HTLV-I strain demonstrated a divergence of 3.4% with respect to the sequence of the ATK-1 prototype (Japan) and of 1.7% of the strain HS-35 (Caribbean) showing a greater relation with the Caribbean strains than with those from Japan. CONCLUSIONS: The presence of HTLV-II subtype has been confirmed among intravenous drug addicts in Spain. Isolation and characterization of the HTLV-I strain demonstrated that this also circulating around Spain despite its South American origin.