Two new human T-lymphotropic virus type I phylogenetic subtypes in seroindeterminates, a Mbuti pygmy and a Gabonese, have closest relatives among African STLV-I strains.
Six new HTLV-I strains from seroindeterminate individuals were analyzed: four from Gabon, one from a Mbuti Efe pygmy in Congo (formerly Zaire), and one from a Congolese patient residing in Belgium. The LTR and env regions were sequenced and phylogenetic analyses were performed to characterize the new strains. Nucleotide divergence and phylogeny results showed that four of the new strains belong to the HTLV-Ib Central African subtype. The other two strains, one from the Efe pygmy and one from Gabon, lie on distinct branches of the LTR and env trees with respect to the four major HTLV-I subtypes. Despite the low bootstrap values, likelihood mapping analyses proved that these strains can be considered two new HTLV-I molecular subtypes, putatively named HTLV-Ie and HTLV-If. A relation exists in the phylogenetic trees and in the likelihood maps between the new subtypes and African STLV-I strains from Papio spp. and Cercopithecus spp., suggesting one or more interspecies transmission events in the past. This study demonstrates that the phylogenetic subtyping of HTLV-I in the African continent is far from being completed and that samples presenting an indeterminate serology can potentially belong to new subtypes in humans. In addition, present day serological tests do not reliably type strains within the HTLV-Ib Central African subtype.
Salemi
M
M
Rega Institute for Medical Research, Katholieke Universiteit Leuven, Belgium. marco.salemi@uz.kuleuven.ac.be
Van Dooren
S
S
Audenaert
E
E
Delaporte
E
E
Goubau
P
P
Desmyter
J
J
Vandamme
A M
AM
D001483:Base Sequence; D002874:Chromosome Mapping; D004279:DNA, Viral; D015023:Democratic Republic of the Congo; D005681:Gabon; D015686:Gene Products, env / Q000235:genetics; D014644:Genetic Variation; D015490:HTLV-I Infections / Q000821:virology; D015368:Human T-lymphotropic virus 1 / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D012091:Repetitive Sequences, Nucleic Acid; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics; D015303:Simian T-lymphotropic virus 1 / Q000145:classification*; D054299:env Gene Products, Human Immunodeficiency Virus
D004279:DNA, Viral; D015686:Gene Products, env; D015682:Retroviridae Proteins, Oncogenic; D054299:env Gene Products, Human Immunodeficiency Virus; C055265:gp21 protein, Human T-lymphotropic virus 1