The tonsillar microbiome of Streptococcus suis diseased piglets

S. suis is a complex pathogen with a large diversity of pathogenic and commensal strains, and there is no cross protective vaccine. Pathogenic strains are hypothesized to enter the host via the palatine tonsils, a lymphoid organ colonized by S. suis in virtually all pigs. In order to enter the host bloodstream via the tonsils, pathogenic S. suis strains first need to colonize the tonsillar biofilm. It is possible that this is facilitated during mi- crobial dysbiosis when there is reduced competition from commensal bacteria. We have utilized both amplicon and shotgun sequencing approaches to quantify the tonsillar mi- crobiome of S. suis diseased piglets and healthy controls. We find microbiome composi- tion and diversity to differ between controls and symptomatic animals, even weeks be- fore disease occurrence. The tonsils of symptomatic animals also contain a higher relative abundance of genes that are conserved in disease-associated S. suis strains but lacking in commensals. Moreover, we find non-symptomatic littermates of diseased piglets to have an intermediate microbiome profile. We hypothesize that some sows provide piglets with a disease-prone microbiome, possibly due to direct transmission of an unhealthy microbi- ome or deficient colostrum. Within the PIGSs consortium we are utilizing the results from this study in vaccine and probiotics development.

This study was presented at the WIAS Annual Conference (WAC) 2020.