Human T cell lymphotropic virus type 2a strains among HIV type 1-coinfected patients from Brazil have originated mostly from Brazilian Amerindians

Abstract

The human T cell lymphotropic virus type 2 (HTLV-2) is found mainly in Amerindians and in intravenous drug users (IDUs) from urban areas of the United States, Europe, and Latin America. Worldwide, HTLV-2a and HTLV-2b subtypes are the most prevalent. Phylogenetic analysis of HTLV-2 isolates from Brazil showed the HTLV-2a subtype, variant -2c, which spread from Indians to the general population and IDUs. The present study searched for the types of HTLV-2 that predominate among HIV-1-coinfected patients from southern and southeastern Brazil. Molecular characterization of the LTR, env, and tax regions of 38 isolates confirmed the HTLV-2c variant in 37 patients, and one HTLV-2b in a patient from Paraguay. Phylogenetic analysis of sequences showed different clades of HTLV-2 associated with risk factors and geographic region. These clades could represent different routes of virus transmission and/or little diverse evolutionary rates of virus. Taking into account the results obtained in the present study and the lack of the prototypic North American HTLV-2a strain and HTLV-2b subtypes commonly detected among HIV-coinfected individuals worldwide, we could speculate on the introduction of Brazilian HTLV-2 strains in such populations before the introduction of HIV.

FIG. 1.

Amino acid alignment of the tax region (A) and schematic Tax protein structure (B) among human T cell lymphotropic virus (HTLV)-2a (Mo prototype), HTLV-2b (NRA prototype), HTLV-2c (BRLO02-02), and HTLV-2d (Efe2) subtypes, highlighting the stop codon position in each sequence that results in an additional 25 amino acids at the C-terminal end of the Tax protein of HTLV-2b and HTLV-2c and 13 amino acids in HTLV-2d subtypes in relation to the HTLV-2a subtype. Note that the first amino acids are encoded in the env region not displayed in these sequence alignments.

FIG. 2.

Map of Brazil showing the location of the São Paulo state (highlighting São Paulo and Jundiaí cities, distance 37 miles) and the Paraná state (highlighting Londrina city, 330 miles from São Paulo city).

FIG. 3.

Dendrogram showing the phylogenetic relationship between 458 bp of the long terminal repeat (LTR) (nt. 181–638 in relation to the Mo prototype—AN M10060) region of the HTLV-2 strains, including sequences from the south and southeast regions of Brazil (GenBank AN GU573730–GU573743, and JQ435902–JQ435910) in bold. Bootstrap values above 65% and zero length using the likelihood ratio test with p<0.001 (**) and p≤0.05 (*) in key branches are depicted. The HTLV-2d Efe2 isolate was used as the outgroup.

FIG. 4.

Dendrogram showing the phylogenetic relationship between 1,065 bp of the env (nt. 5573–6637 in relation to the Mo prototype—AN M10060) region of the HTLV-2 strains, including sequences from the south and southeast regions of Brazil (GenBank AN HM770390–HM770425 and JQ435911) in bold. Bootstrap values above 65% and zero length using the likelihood ratio test with p<0.001 (**) and p≤0.05 (*) in key branches are depicted. The HTLV-2d Efe2 isolate was used as the outgroup.

FIG. 5.

Dendrogram showing the phylogenetic relationship between 1,068 bp of the tax (nt. 7213–8280 in relation to the Mo prototype—AN M10060) region of the HTLV-2 strains, including sequences from the south and southeast regions of Brazil (GenBank AN JN887712–JN887736) in bold. Bootstrap values above 65% and zero length using the likelihood ratio test with p<0.001 (**) and p≤0.05 (*) in key branches are depicted. The HTLV-2d Efe2 isolate was used as the outgroup.