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Volume 32, Number 7—July 2026

Research Letter

Emergence of West African Human T-Lymphotropic Virus 1aC Subgroup, Brazilian Amazon

Jean de Melo Silva, Emmily Myrella Vasconcelos Mourão, Enzo Miranda Santos, Luma Silva Mineiro, Paulo Henrique Rodrigues de Souza, Leonardo Calheiros de Oliveira, Jacqueline da Silva Batista, Giselle Moura Guimarães Marques, Carolina Rosadas de Oliveira, Graham P. Taylor, Antonio Carlos Rosário Vallinoto, and Gemilson Soares PontesComments to Author 
Author affiliation: Institute of Biological Science, Federal University of Amazonas, Manaus, Brazil (J. de Melo Silva, G.S. Pontes); Leônidas and Maria Deane Institute–ILMD/Fiocruz Amazônia, Manaus (E.M.V. Mourão); Foundation of Hematology and Hemotherapy of Amazonas, Manaus (E.M. Santos); National Institute of Amazonian Research, Manaus (L.S. Mineiro, P.H.R. de Souza, L.C. de Oliveira, J. da Silva Batista, G.M. Guimarães Marques, G.S. Pontes); Faculty of Medicine, Imperial College London, London, UK (C.R. de Oliveira, G.P. Taylor); National Centre for Human Retrovirology, St. Mary's Hospital, Imperial College Healthcare NHS Trust, London (G.P. Taylor); Federal University of Pará, Belém, Brazil (A.C.R. Vallinoto)

Main Article

Figure 1

Phylogenetic tree of HTLV isolates in study of emergence of West African HTLV-1aC subgroup, Brazilian Amazon. A) HTLV-1 sequences obtained in this study (bold text) were analyzed with 38 reference sequences from GenBank. The Manaus isolates clustered within the Cosmopolitan subtype, including the Transcontinental subgroup (WDM1168_BrMao and WQC1199_BrMao) and the West African subgroup (SSS850_BrMao). B) The HTLV-2 sequence identified in Manaus (JDC1001_BrMao, bold text) was analyzed with 49 reference sequences from GenBank (accession numbers provided) and clustered within subtype HTLV-2c. Trees were inferred using the maximum-likelihood method under the Kimura 2-parameter substitution model. The best-scoring trees (log-likelihood −14,610.1 for panel A and −2,247.45 for panel B) were selected through heuristic searches initiated with neighbor-joining and maximum parsimony starting topologies. Branch support was assessed with 1,000 bootstrap replicates. HTLV, human T-lymphotropic virus.

Figure 1. Phylogenetic tree of HTLV isolates in study of emergence of West African HTLV-1aC subgroup, Brazilian Amazon. A) HTLV-1 sequences obtained in this study (bold text) were analyzed with 38 reference sequences from GenBank. The Manaus isolates clustered within the Cosmopolitan subtype, including the Transcontinental subgroup (WDM1168_BrMao and WQC1199_BrMao) and the West African subgroup (SSS850_BrMao). B) The HTLV-2 sequence identified in Manaus (JDC1001_BrMao, bold text) was analyzed with 49 reference sequences from GenBank (accession numbers provided) and clustered within subtype HTLV-2c. Trees were inferred using the maximum-likelihood method under the Kimura 2-parameter substitution model. The best-scoring trees (log-likelihood −14,610.1 for panel A and −2,247.45 for panel B) were selected through heuristic searches initiated with neighbor-joining and maximum parsimony starting topologies. Branch support was assessed with 1,000 bootstrap replicates. HTLV, human T-lymphotropic virus.

Main Article

Page created: May 28, 2026
Page updated: June 23, 2026
Page reviewed: June 23, 2026
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