title: The origin and evolutionary history of HIV-1 subtype C in Senegal.
abstract: BACKGROUND
  The classification of HIV-1 strains in subtypes and Circulating Recombinant Forms (CRFs) has helped in tracking the course of the HIV pandemic. In Senegal, which is located at the tip of West Africa, CRF02_AG predominates in the general population and Female Sex Workers (FSWs). In contrast, 40% of Men having Sex with Men (MSM) in Senegal are infected with subtype C. In this study we analyzed the geographical origins and introduction dates of HIV-1 C in Senegal in order to better understand the evolutionary history of this subtype, which predominates today in the MSM population
  
  
  RESULTS
  We used a combination of phylogenetic analyses and a Bayesian coalescent-based approach, to study the phylogenetic relationships in pol of 56 subtype C isolates from Senegal with 3,025 subtype C strains that were sampled worldwide. Our analysis shows a significantly well supported cluster which contains all subtype C strains that circulate among MSM in Senegal. The MSM cluster and other strains from Senegal are widely dispersed among the different subclusters of African HIV-1 C strains, suggesting multiple introductions of subtype C in Senegal from many different southern and east African countries. More detailed analyses show that HIV-1 C strains from MSM are more closely related to those from southern Africa. The estimated date of the MRCA of subtype C in the MSM population in Senegal is estimated to be in the early 80's.
  
  
  CONCLUSIONS
  Our evolutionary reconstructions suggest that multiple subtype C viruses with a common ancestor originating in the early 1970s entered Senegal. There was only one efficient spread in the MSM population, which most likely resulted from a single introduction, underlining the importance of high-risk behavior in spread of viruses.
authors.affiliation: UMI233, TransVIHMI, IRD (Institut de Recherche pour le Développement) and University of Montpellier 1, Montpellier, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Jung
authors.forename: Nafissatou
authors.initials: N
authors.lastname: Leye
authors.forename: Nicole
authors.initials: N
authors.lastname: Vidal
authors.forename: Denis
authors.initials: D
authors.lastname: Fargette
authors.forename: Halimatou
authors.initials: H
authors.lastname: Diop
authors.forename: Coumba
authors.initials: C
authors.lastname: Toure Kane
authors.forename: Olivier
authors.initials: O
authors.lastname: Gascuel
authors.forename: Martine
authors.initials: M
authors.lastname: Peeters
mesh_terms: D001499:Bayes Theorem; D019143:Evolution, Molecular; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000453:epidemiology / Q000821:virology*; D015497:HIV-1 / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D010802:Phylogeny; D012675:Senegal; D017423:Sequence Analysis, RNA; D054302:pol Gene Products, Human Immunodeficiency Virus / Q000235:genetics
chemical_list: D054302:pol Gene Products, Human Immunodeficiency Virus