Phylogenetic subtypes of human T-lymphotropic virus type I and their relations to the anthropological background.

Abstract

Isolates of human T-lymphotropic virus type I (HTLV-I) were phylogenetically analyzed from native inhabitants in India and South America (Colombia and Chile) and from Ainu (regarded as pure Japanese descendants from the preagricultural "Jomon" period). Their genomes were partially sequenced together with isolates from Gabon in central Africa and from Ghana in West Africa. The phylogenetic tree was constructed from the sequence data obtained and those of previously reported HTLV-I isolates and simian T-lymphotropic virus type I (STLV-I) isolates. The heterogeneity of HTLV-I was recently recognized, and one major type, generally called the "cosmopolitan" type, contained Japanese, Caribbean, and West African isolates. The phylogenetic tree constructed in the present study has shown that this cosmopolitan type can be further grouped into three lineages (subtypes A, B, and C). Subtype A consists of some Caribbean, two South American, and some Japanese isolates, including that from the Ainu, in addition to an Indian isolate, and subtype B consists of other Japanese isolates in addition to another Indian isolate, suggesting that there might be at least two ancestral lineages of the Japanese HTLV-I. Subtype A implies a close connection of the Caribbean and South American natives with the Japanese and thereby a possible migration of the lineage to the American continent via Beringia in the Paleolithic era. Subtype C consists of the West African and other Caribbean isolates, indicating that not all but part of the Caribbean strains directly originated from West Africa probably during the period of slave trade. The tree also has shown that the HTLV-I isolate from Gabon in central Africa forms a cluster with STLV-I from a chimpanzee, suggesting a possible interspecies transmission between man and the chimpanzee in the past. No specific clustering was observed in the tree in relation to manifestations of the disease such as adult T-cell leukemia and HTLV-I-related neurological disorders. Thus, the topology of the phylogenetic tree reflects the movement of people carrying the virus in the past.

Sequence and phylogenetic analysis of human T cell lymphotropic virus type 1 from Tumaco, Colombia

“…Phylogenetic analyses of mitochondrial DNA (Horai et al 1993) and HLA haplotype sequence comparisons (Sonoda et al 1991) also suggest a relationship between Japanese and paleo-indian people from South America (Miura et al 1994). In contrast, other researchers have suggested that the American isolates originated from African isolates based on the absence of HTLV-1 among Amerindians and the high prevalence of infection among individuals of African descendents in the Caribbean area and in South America (Song et al 1995).…”

On the phylogenetic placement of human T cell leukemia virus type 1 sequences associated with an Andean mummy

“…1, showed only low levels of support for many internal branches. Boundaries of the five Cosmopolitan subclades A-E, previously described as subtype taxa by Gasmi et al (1994), Miura et al (1994) and Van Dooren et al (1998) are readily located on the cladogram (Fig. 1).…”

“…A salient point of discussion concerns whether an "Out-of-Africa" migration in connection with increased global travel over the past several centuries is sufficient to explain the fact that HTLV-1 is found, endemically or sporadically, in most human populations worldwide (Gallo et al, 1983;Wong-Staal and Gallo, 1985;Van Dooren et al, 1998). An alternative view is that the virus was present in Asian and American populations long before the modern era (Ishida et al, 1985;Miura et al, 1994), and has co-descended with its regional human host populations for thousands of years. Recently, the debate has been focused at the empirical level of molecular phylogenetic analysis, especially on how best to explain the phylogenetic origins and structure of a large, globally distributed lineage of HTLV-1 named the "Cosmopolitan" clade into which almost all extant non-African, and a number of African, HTLV-1 strains fall.…”

“…Debate has characterized this area almost as long as the virus has been studied (Gallo et al, 1983;Ishida et al, 1985;Wong-Staal and Gallo, 1985), and new research and divergent interpretation continue to emerge (Miura et al, 1994;Van Dooren et al, 1998). A salient point of discussion concerns whether an "Out-of-Africa" migration in connection with increased global travel over the past several centuries is sufficient to explain the fact that HTLV-1 is found, endemically or sporadically, in most human populations worldwide (Gallo et al, 1983;Wong-Staal and Gallo, 1985;Van Dooren et al, 1998).…”

Molecular Epidemiology and Clinical Features of Human T Cell Lymphotropic Virus Type 1 Infection in Spain

“…6 Based on phylogenetic analyses of long terminal repeat (LTR) regions, HTLV-1 strains are classified into seven subtypes named a to g. Al least three of them (the Cosmopolitan, HTLV-1 subtype a; the Central African, HTLV-1 subtype b; and the Melanesian, HTLV-1 subtype c) have arisen from different interspecies transmission episodes from simian T cell leukemia virus type 1 (STLV-1)-infected monkeys to humans, followed by variable periods of evolution in the human host. 7 Subtype 1a, or Cosmopolitan, is distributed worldwide, 8 whereas the rest of HTLV-1 variants are restricted to specific regions. Subtypes 1 b, d, e, and g have been isolated in different regions of Central Africa.…”