title: Microsatellite analysis supports clonal propagation and reduced divergence of Trypanosoma vivax from asymptomatic to fatally infected livestock in South America compared to West Africa.
abstract: BACKGROUND
  Mechanical transmission of the major livestock pathogen Trypanosoma vivax by other biting flies than tsetse allows its spread from Africa to the New World. Genetic studies are restricted to a small number of isolates and based on molecular markers that evolve too slowly to resolve the relationships between American and West African populations and, thus, unable us to uncover the recent history of T. vivax in the New World.
  
  
  METHODS
  T. vivax genetic diversity, population structure and the source of outbreaks was investigated through the microsatellite multiloci (7 loci) genotype (MLGs) analysis in South America (47isolates from Brazil, Venezuela and French Guiana) and West Africa (12 isolates from The Gambia, Burkina Faso, Ghana, Benin and Nigeria). Relationships among MLGs were explored using phylogenetic, principal component and STRUCTURE analyses.
  
  
  RESULTS
  Although closely phylogenetically related, for the first time, genetic differences were detected between T. vivax isolates from South America (11 genotypes/47 isolates) and West Africa (12 genotypes/12 isolates) with no MLGs in common. Diversity was far greater across West Africa than in South America, where genotypes from Brazil (MLG1-6), Venezuela (MLG7-10) and French Guiana (MLG11) shared similar but not identical allele composition. No MLG was exclusive to asymptomatic (endemic areas) or sick (outbreaks in non-endemic areas) animals, but only MLGs1, 2 and 3 were responsible for severe haematological and neurological disorders.
  
  
  CONCLUSIONS
  Our results revealed closely related genotypes of T. vivax in Brazil and Venezuela, regardless of endemicity and clinical conditions of the infected livestock. The MLGs analysis from T. vivax across SA and WA support clonal propagation, and is consistent with the hypothesis that the SA populations examined here derived from common ancestors recently introduced from West Africa. The molecular markers defined here are valuable to assess the genetic diversity, to track the source and dispersion of outbreaks, and to explore the epidemiological and pathological significance of T. vivax genotypes.
authors.forename: Herakles A
authors.initials: HA
authors.lastname: Garcia
authors.forename: Adriana C
authors.initials: AC
authors.lastname: Rodrigues
authors.forename: Carla Mf
authors.initials: CM
authors.lastname: Rodrigues
authors.forename: Zakaria
authors.initials: Z
authors.lastname: Bengaly
authors.forename: Antonio Hh
authors.initials: AH
authors.lastname: Minervino
authors.forename: Franklin
authors.initials: F
authors.lastname: Riet-Correa
authors.forename: Rosangela Z
authors.initials: RZ
authors.lastname: Machado
authors.forename: Fernando
authors.initials: F
authors.lastname: Paiva
authors.forename: Jael S
authors.initials: JS
authors.lastname: Batista
authors.forename: Luis
authors.initials: L
authors.lastname: Neves
authors.forename: Patrick B
authors.initials: PB
authors.lastname: Hamilton
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brasil. mmgteix@icb.usp.br.
authors.forename: Marta Mg
authors.initials: MM
authors.lastname: Teixeira
mesh_terms: D000354:Africa, Western / Q000453:epidemiology; D000818:Animals; D014644:Genetic Variation; D005838:Genotype; D058751:Livestock; D018895:Microsatellite Repeats; D010802:Phylogeny; D013020:South America / Q000453:epidemiology; D016689:Trypanosoma vivax / Q000235:genetics*; D014353:Trypanosomiasis, African / Q000453:epidemiology / Q000235:genetics / Q000401:mortality / Q000469:parasitology*