Genetic Structuration, Demography and Evolutionary History of Mycobacterium tuberculosis LAM9 Sublineage in the Americas as Two Distinct Subpopulations Revealed by Bayesian Analyses

PLoS One. 2015 Oct 30;10(10):e0140911. doi: 10.1371/journal.pone.0140911. eCollection 2015.

Abstract

Tuberculosis (TB) remains broadly present in the Americas despite intense global efforts for its control and elimination. Starting from a large dataset comprising spoligotyping (n = 21183 isolates) and 12-loci MIRU-VNTRs data (n = 4022 isolates) from a total of 31 countries of the Americas (data extracted from the SITVIT2 database), this study aimed to get an overview of lineages circulating in the Americas. A total of 17119 (80.8%) strains belonged to the Euro-American lineage 4, among which the most predominant genotypic family belonged to the Latin American and Mediterranean (LAM) lineage (n = 6386, 30.1% of strains). By combining classical phylogenetic analyses and Bayesian approaches, this study revealed for the first time a clear genetic structuration of LAM9 sublineage into two subpopulations named LAM9C1 and LAM9C2, with distinct genetic characteristics. LAM9C1 was predominant in Chile, Colombia and USA, while LAM9C2 was predominant in Brazil, Dominican Republic, Guadeloupe and French Guiana. Globally, LAM9C2 was characterized by higher allelic richness as compared to LAM9C1 isolates. Moreover, LAM9C2 sublineage appeared to expand close to twenty times more than LAM9C1 and showed older traces of expansion. Interestingly, a significant proportion of LAM9C2 isolates presented typical signature of ancestral LAM-RDRio MIRU-VNTR type (224226153321). Further studies based on Whole Genome Sequencing of LAM strains will provide the needed resolution to decipher the biogeographical structure and evolutionary history of this successful family.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Americas / epidemiology
  • Bayes Theorem
  • Demography
  • Evolution, Molecular
  • Gene Frequency
  • Genotype
  • Humans
  • Mycobacterium tuberculosis / genetics*
  • Phylogeny
  • Tuberculosis, Pulmonary / epidemiology
  • Tuberculosis, Pulmonary / microbiology

Grants and funding

Yann Reynaud was awarded a Calmette and Yersin postdoctoral fellowship by the Institut Pasteur. No additional external funding was received for this study