Identification and characterization of genes contributing to the virulence of the major swine pathogen Streptococcus suis

Gussak, Alex; Ferrando, M.L.; Murray, Gemma; Hossain, M.; Weinert, L.; Baarlen, P. van; Wells, J.M.


Streptococcus suis bacteria cause serious infectious diseases in piglets, associated with substantial piglet mortality and major economic losses to the pig industry. S. suis is also a zoonotic pathogen and human infections worldwide have increased significantly in the past years. Different isolates of S. suis are highly diverse in terms of genotype and serotype and asymptomatic carriage is common in pigs, hampering the development of effective control strategies. Our group is part of a European project aimed at increasing our understanding of S. suis disease mechanisms from the genomic sequences of more than 1800 S. suis strains isolated from healthy and diseased piglets from different countries including Denmark, Germany, Spain and the Netherlands. A genome-wide-association study was used to identify a set of genes that were highly enriched in the pathogenic isolates. To investigate the function of these genes in virulence, we generated KO mutants of selected genes in S. suis using a novel genome editing approach. These genetic mutants are being characterized in a variety of in vitro infection models mimicking relevant stages of infection, including organoid systems. This approach will increase our understanding of the mechanisms underlying S. suis infection and contribute towards the development of effective control strategies.