Microbiome development in piglets and colonisation resistance against swine bacterial pathogens

The host-microbiota interplay plays a decisive role in regulating and directing the healthy or diseased status of individuals. Susceptibility or resistance against infectious disease is strongly influenced by the interaction of the microbiota with host innate immune response, and microbiota mediates colonization resistance against microbial pathogens. Although intestinal microbiota has been the most intensively investigated, little is known on tonsillar microbiota and there is now great interest to characterize tonsil microbiomes since tonsils can be colonized by harmful microbes, and the pig palatine tonsils are the first point of entry of diverse infectious microbes including Streptococcus suis.

S. suis is the most common bacterial pathobiont species that can cause fatal diseases in post-weaned piglets. High abundance of S. suis in the porcine tonsillar microbiota may indicate a dysbalance of microbial colonization or dysbiosis and the onset of infection.  At HMI, using a high-throughput screening effort to culture bacteria from the microbiota of healthy piglets, we aim to identify bacterial isolates producing antimicrobial peptides with specific activity against several relevant swine pathogens including S. suis. We hypothesize that introducing microbial consortia, microbial preparations that contain multiple antagonist strains, in the tonsil of pre-weaned and post-weaned piglets could allow their proper, unbiased colonization of the tonsils and reduction of S. suis numbers. In addition, changes in host innate immune status upon introduction of foreign bacterial species will be evaluated  by assessing maturation of the mucosal innate immune system. The project outputs will provide novel evidence for prevention of, and control strategies against infections caused by respiratory swine pathogens through the manipulation of the microbiota and stimulation and maturation of the innate immune system.

The research outlined here is part of the EU project PIGSs, https://cordis.europa.eu/project/rcn/210504_en.html