COMPLETE NUCLEOTIDE-SEQUENCE OF AN AFRICAN HUMAN T-LYMPHOTROPIC VIRUSTYPE-II SUBTYPE-B ISOLATE (HTLV-II-GAB) - MOLECULAR AND PHYLOGENETIC ANALYSIS

We report the first complete nucleotide sequence of an African human T -cell lymphotropic virus type II, This new strain, called HTLV-II-Gab (Gab), was obtained from the uncultured peripheral blood mononuclear c ells of a 44-year-old healthy Gabonese male who lived in a remote rura l area, with neither history of blood transfusion nor sexual intercour se with non-Africans, Using nested PCR, 25 overlapping fragments, repr esenting the entire proviral genome, were obtained, cloned and sequenc ed, The overall nucleotide sequence comparison with the four other ava ilable complete HTLV-II genomes indicated that Gab was more closely re lated to the HTLV-II subtype b prototypes (98.9, 99.3 and 98.2% nucIeo tide similarity with G12, NRA and GU respectively) than to the subtype a prototype (95.1% nucleotide similarity with Mo), Restriction profil es studies and phylogenetic analyses confirmed that Gab was a subtype b strain. However, this strain represents a newly described restrictio n fragment length polymorphism subtype, closely related to one of the rare partial ly sequenced African isolates originating from a pygmy li ving in Cameroon (PYGCAM), Nevertheless, the very low genetic divergen ce observed between this new African strain and the American strains r aises several questions on the origins and level of genetic variabilit y over time of this human retrovirus.