title: African origin of human T-lymphotropic virus type 2 (HTLV-2) supported by a potential new HTLV-2d subtype in Congolese Bambuti Efe Pygmies.
abstract: We identified a potential new subtype within human T-cell lymphotropic virus type 2 (HTLV-2), HTLV-2d, present in members of an isolated Efe Bambuti Pygmy tribe. Two of 23 Efe Pygmies were HTLV-2 seropositive, with HTLV-2 Western blot and enzyme-linked immunosorbent assay reactivities. From one of them the entire genome of the HTLV-2 strain Efe2 could be amplified and sequenced. In all gene regions analyzed, this strain was the most divergent HTLV-2 strain, differing by 2.4% (tax/rex) to 10.7% (long terminal repeat) from both subtypes HTLV-2a and HTLV-2b, yet major functional elements are conserved. The similarity between the HTLV-2 Efe2 Gag and Env proteins and the corresponding HTLV-2a and -2b proteins is consistent with the observed serological reactivity. In the proximal pX region, one of the two alternative splice acceptor sites is abolished in HTLV-2 Efe2. Another interesting feature of this potential new subtype is that it has a Tax protein of 344 amino acids (aa), which is intermediate in length between the HTLV-2a Tax protein (331 aa) and the HTLV-2b and -2c Tax proteins (356 aa) and similar to the simian T-cell lymphotropic virus type 2 (STLV-2) PP1664 Tax protein. Together these two findings suggest a different phenotype for the HTLV-2 Efe2 strain. Phylogenetic analyses confirmed that the Pygmy Efe2 strain potentially belonged to a new and quite divergent subtype, HTLV-2d. When the STLV-2 bonobo viruses PP1664 and PanP were used as an outgroup, it was clear that the Pygmy HTLV-2 Efe2 strain had the longest independent evolution and that HTLV-2 evolution is consistent with an African origin.
authors.affiliation: Rega Institute for Medical Research and University Hospitals, Katholieke Universiteit Leuven, Belgium. annemie.vandamme@uz.kuleuven.ac.be
authors.forename: A M
authors.initials: AM
authors.lastname: Vandamme
authors.forename: M
authors.initials: M
authors.lastname: Salemi
authors.forename: M
authors.initials: M
authors.lastname: Van Brussel
authors.forename: H F
authors.initials: HF
authors.lastname: Liu
authors.forename: K
authors.initials: K
authors.lastname: Van Laethem
authors.forename: M
authors.initials: M
authors.lastname: Van Ranst
authors.forename: L
authors.initials: L
authors.lastname: Michels
authors.forename: J
authors.initials: J
authors.lastname: Desmyter
authors.forename: P
authors.initials: P
authors.lastname: Goubau
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003223:Congo; D004279:DNA, Viral; D005006:Ethnicity; D016355:Genes, pX; D016679:Genome, Viral; D015491:HTLV-II Infections / Q000097:blood / Q000276:immunology / Q000821:virology*; D015367:Human T-lymphotropic virus 2 / Q000145:classification* / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011533:Proviruses / Q000235:genetics; D012194:RNA-Directed DNA Polymerase / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D004279:DNA, Viral; D012194:RNA-Directed DNA Polymerase