title: HTLV-1aA introduction into Brazil and its association with the trans-Atlantic slave trade.
abstract: Human T-lymphotropic virus (HTLV) is an endemic virus in some parts of the world, with Africa being home to most of the viral genetic diversity. In Brazil, HTLV-1 is endemic amongst Japanese and African immigrant populations. Multiple introductions of the virus in Brazil from other epidemic foci were hypothesized. The long terminal repeat (LTR) region of HTLV-1 was used to infer the origin of the virus in Brazil, using phylogenetic analysis.
  
  
  
  LTR sequences were obtained from the HTLV-1 database (http://htlv1db.bahia.fiocruz.br). Sequences were aligned and maximum-likelihood and Bayesian tree topologies were inferred. Brazilian specific clusters were identified and molecular-clock and coalescent models were used to estimate each cluster's time to the most recent common ancestor (tMRCA).
  
  
  
  Three Brazilian clusters were identified with a posterior probability ranged from 0.61 to 0.99. Molecular clock analysis of these three clusters dated back their respective tMRCAs between the year 1499 and the year 1668. Additional analysis also identified a close association between Brazilian sequences and new sequences from South Africa.
  
  
  
  Our results support the hypothesis of a multiple introductions of HTLV-1 into Brazil, with the majority of introductions occurring in the post-Colombian period. Our results further suggest that HTLV-1 introduction into Brazil was facilitated by the trans-Atlantic slave trade from endemic areas of Africa. The close association between southern African and Brazilian sequences also suggested that greater numbers of the southern African Bantu population might also have been part of the slave trade than previously thought.
authors.affiliation: Laboratory of Hematology, Genetics and Computational Biology/Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil. Electronic address: amoussaroukiyath@yahoo.fr.
authors.forename: Adjile Edjide Roukiyath
authors.initials: AE
authors.lastname: Amoussa
authors.affiliation: Africa Centre for Health and Population Studies, University of Kwazulu-Natal, Durban, South Africa. Electronic address: ewilkinson83@gmail.com.
authors.forename: Eduan
authors.initials: E
authors.lastname: Wilkinson
authors.affiliation: Laboratory of Hematology, Genetics and Computational Biology/Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil; University of Rome "Tor Vergata", Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Giovanetti
authors.affiliation: Laboratory of Hematology, Genetics and Computational Biology/Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil; Catholic University of Salvador, Salvador, Bahia, Brazil.
authors.forename: Filipe Ferreira
authors.initials: FF
authors.lastname: de Almeida Rego
authors.affiliation: Laboratory of Hematology, Genetics and Computational Biology/Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil; Bahia School of Medicine and Public Health/Bahia Foundation for Development of Science, Salvador, Bahia, Brazil.
authors.forename: Thessika Hialla A
authors.initials: TH
authors.lastname: Araujo
authors.affiliation: Laboratory of Hematology, Genetics and Computational Biology/Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil.
authors.forename: Marilda
authors.initials: M
authors.lastname: de Souza Gonçalves
authors.affiliation: Africa Centre for Health and Population Studies, University of Kwazulu-Natal, Durban, South Africa.
authors.forename: Tulio
authors.initials: T
authors.lastname: de Oliveira
authors.affiliation: Laboratory of Hematology, Genetics and Computational Biology/Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil. Electronic address: lalcan@bahia.fiocruz.br.
authors.forename: Luiz Carlos Junior
authors.initials: LC
authors.lastname: Alcantara
mesh_terms: D001267:Atlantic Ocean; D001938:Brazil / Q000453:epidemiology; D063948:Enslaved Persons; D058872:Epidemics; D005814:Genes, Viral; D015490:HTLV-I Infections / Q000453:epidemiology* / Q000821:virology; D015368:Human T-lymphotropic virus 1 / Q000235:genetics*; D006801:Humans; D017422:Sequence Analysis, DNA; D013019:South Africa / Q000453:epidemiology; D020079:Terminal Repeat Sequences
keywords: Brazil; HTLV; Southern Africa; Trans-Atlantic slave trade