Seleção diversificadora em Corynebacterium Pseudotuberculosis

Abstract

Corynebacterium pseudotuberculosis is a Gram-positive, facultative intracellular bacterium with veterinary and medical importance and a global distribution. It infects a variety of mammals, such as sheep, goats, horses, buffalo and humans, and causes economic losses in animal production. Biovar Equi is nitrate positive and has horse and buffalo as exclusive hosts. Biovar Ovis is nitrate negative and has preference for sheep and goats. Antibiotic treatments have reduced efficiency due to the protection provided by the abscesses and current vaccines have different protection efficiency in different hosts. The analysis of positive (diversifying) selection is useful to identify adaptive mutations in this pathogen and to reveal mechanisms of host adaptation and probable targets for control methods. A genome-scale positive selection analysis was performed in C. pseudotuberculosis using 29 strains from different hosts, biovars and countries. The phylogenomic analysis suggested that Ovis diverged recently from Equi biovar, probably after specialization for a new host range. Positive selection was detected in 11 genes, most involved in host colonization processes. The results provide information about the adaptive mutations related to the species lyfestile and suggest a probable drug target.