Diversity ofstrains from pigs across Ontario, Canada.

Abstract

causes highly contagious swine enzootic pneumonia worldwide. It has been reported that highly diversifiedstrains exist in different parts of the world. We foundgene sequencing analysis, an affordable and simple-to-perform typing method, to be specific and highly sensitive when applied to the molecular typing of 113-positive clinical samples directly without culture. The samples were submitted to the Animal Health Laboratory at the University of Guelph (Ontario, Canada) during 2009-2017 from 40 different geographic areas in Ontario. Using a previously described criterion of grouping strains with&#x2009;<&#x2009;4-bp differences into the same molecular type (type), the 113 clinical samples clustered into 19genotypes. Dominant types were found in 2016 and 2017 only, indicating that highly diversifiedstrains existed in Ontario. Some strains from the same geographic location but different years had the same sequence types, indicating that the same strain types circulate persistently in the field. Differentgenotypes were also identified from similar geographic locations, indicating that eitherstrains are prone to mutation or that multiple strains can infect the same or nearby swine production units.