The origin of HTLV-1 in southern Bahia by phylogenetic, mtDNA and β-globin analysis

Different hypotheses have been elaborated to explain how the HTLV spread throughout the world. It has been proposed that the virus was introduced in Bahia, during the slave-trade period from the 16th century to 19th century. However, there is no information about the HTLV evolutionary history in southern Bahia. The phylogeny is fundamental in order to clarify its introduction and dispersion. The DNA of 29 samples was extracted, followed by nested-PCR assay for the LTR and DNA sequencing. These sequences were analyzed by phylogenic methods. The mtDNA ancestry markers and βA-globin haplotypes were analyzed by PCR/RFLP. In relation to HTLV subtyping, all samples were classified as cosmopolitan subtype and transcontinental subgroup. Results suggest an ancient post-Columbian introduction of HTLV-1a-A associated with the slave trade between the XVI and late XIX centuries in southern Bahia. As regards the ethnicity of HTLV-infected women, the haplotype characterization of β-globin gene and the mtDNA ethnicity of HTLV-infected women, we have detected a major African contribution, with a predominance of Benin and Bantu types. HTLV-1 infection is spread in Bahia and the point of origin was possibly Salvador.