HTLV-IS IN ARGENTINA ARE PHYLOGENETICALLY SIMILAR TO THOSE OF OTHER SOUTH-AMERICAN COUNTRIES, BUT DIFFERENT FROM HTLV-IS IN AFRICA

To understand the origin and past dissemination of human T-cell leukem ia/lymphotropic virus type I (HTLV-I) in Latin America, we conducted a phylogenetic study of five new HTLV-I isolates from Argentina. We seq uenced partial fragments of long terminal repeats (LTR) of the new HTL V-ls, and then the sequences were subjected to a phylogenetic analysis for comparison with other HTLV-ls of various geographical origins. Ou r results indicated that all the isolates were members of the Cosmopol itan group. Furthermore, most (four out of five isolates) of the new H TLV-ls belonged to the Transcontinental (A) subgroup, the most widespr ead subgroup of the four subgroups in the Cosmopolitan group. In this subgroup, they were closely related to HTLV-ls found in other South Am erican countries including those of Amerindians, and were different fr om those found in Africa. In contrast, the remaining one HTLV-I (ARGMF ) did not show any clear similarity to known HTLV-I isolates belonging to the Cosmopolitan group. The close similarity of South American HTL V-ls strongly suggests a common origin of the virus in this continent. Our results do not support the proposed idea of recent introduction o f HTLV-I into South America as a consequence of the slave trade from A frica, where phylogenetically different HTLV-ls predominate. (C) 1998 Wiley-Liss, Inc.