Genome-Wide Diversity and Phylogeography of Mycobacterium avium subsp. paratuberculosis in Canadian Dairy Cattle

PLoS One. 2016 Feb 12;11(2):e0149017. doi: 10.1371/journal.pone.0149017. eCollection 2016.

Abstract

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative bacterium of Johne's disease (JD) in ruminants. The control of JD in the dairy industry is challenging, but can be improved with a better understanding of the diversity and distribution of MAP subtypes. Previously established molecular typing techniques used to differentiate MAP have not been sufficiently discriminatory and/or reliable to accurately assess the population structure. In this study, the genetic diversity of 182 MAP isolates representing all Canadian provinces was compared to the known global diversity, using single nucleotide polymorphisms identified through whole genome sequencing. MAP isolates from Canada represented a subset of the known global diversity, as there were global isolates intermingled with Canadian isolates, as well as multiple global subtypes that were not found in Canada. One Type III and six "Bison type" isolates were found in Canada as well as one Type II subtype that represented 86% of all Canadian isolates. Rarefaction estimated larger subtype richness in Québec than in other Canadian provinces using a strict definition of MAP subtypes and lower subtype richness in the Atlantic region using a relaxed definition. Significant phylogeographic clustering was observed at the inter-provincial but not at the intra-provincial level, although most major clades were found in all provinces. The large number of shared subtypes among provinces suggests that cattle movement is a major driver of MAP transmission at the herd level, which is further supported by the lack of spatial clustering on an intra-provincial scale.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alberta
  • Animals
  • Cattle
  • DNA, Bacterial / genetics
  • Feces / microbiology
  • Female
  • Genome, Bacterial
  • Mycobacterium avium subsp. paratuberculosis / genetics*
  • Mycobacterium avium subsp. paratuberculosis / isolation & purification
  • Paratuberculosis / microbiology*
  • Phylogeny
  • Polymorphism, Single Nucleotide
  • Sequence Analysis, DNA
  • Tuberculosis, Bovine / microbiology*

Substances

  • DNA, Bacterial

Grants and funding

This research was supported by the Alberta Livestock and Meat Agency and Dairy Farmers of Canada. SaskMilk provided support in the form of salaries for author DH, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of all authors are articulated in the ‘author contributions’ section.