Genomes of Streptococcus equi subsp. equi from Pennsylvania and Sweden

Streptococcus equi subsp. equi (SEE) is a host-restricted bacterium that causes the common infectious upper respiratory disease known as strangles in horses. Perpetuation of SEE infection appears attributable to inapparent carrier horses because it does not persist long-term in the environment, infect other host mammals or vectors, and result in short-lived immunity. Whether pathogen factors enable SEE to remain in horses without causing clinical signs remains poorly understood. Thus, our objective was to use next-generation sequencing technologies to characterize the genome, and methylome of isolates of SEE from horses with acute clinical strangles and inapparent carrier horses to assess pathogen-associated changes that might reflect adaptions of SEE to the host contributing to inapparent carriage. The accessory genome elements and methylome of SEE isolates from Sweden and Pennsylvania revealed no significant or consistent differences between acute clinical and inapparent carrier isolates of SEE.