NUCLEOTIDE-SEQUENCE AND RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS OF HUMAN T-CELL LYMPHOTROPIC VIRUS TYPE-II (HTLV-II) IN SOUTHERN EUROPE - EVIDENCE FOR THE HTLV-IIA AND HTLV-IIB SUBTYPES

Human T-cell lymphotropic virus type II (HTLV-II) has been subtyped in to two major groups, IIa and IIb, according to molecular studies invol ving env gene sequencing, Subsequently, this retrovirus was further su bclassified by examining the long terminal repeat (LTR). the most dive rgent genomic region. Sequence analysis and restriction fragment-lengt h polymorphism (RFLP) applied to the LTR region identified either four or five groups within the IIa subtype (depending on the restriction e nzyme sets used) and six within the IIb subtype, In this study, we ana lyzed the LTR sequences of 29 samples obtained from HTLV-II-infected i ndividuals living in Spain and Italy, which included 24 injecting drug users (IDUs), three blood donors, and two subjects at risk for HIV/HT LV infection. Sequence analysis and phylogenetic analysis of 720 base pairs of the LTR performed in 10 Spanish samples showed that all of th ese samples belonged to IIb subtype, with a divergence of 7.5% and 1.6 6% compared with MoT (IIa) and NRA/G12 (IIb) isolates, respectively, R FLP analysis demonstrated the presence of the IIb 4-subtype restrictio n pattern in 26 samples, a Ilb5-subtype pattern in one Italian IDU, an d a IIa0-subtype pattern in two Italian samples (blood donors), accord ing to W.M. Switzer's nomenclature, This is the first report of the pr esence of IIb5 in Southern Europe and IIa0 among Italian blood donors, RFLP correlated with nucleotide sequence and phylogenetic data obtain ed in this study, demonstrating the ability of the RFLP method to pred ict the phylogroup of HTLV-II-infected samples.