AbstractsBiology & Animal Science

Haemophilus parasuis and Streptococcus suis are residents of tonsils of the soft palate in healthy pigs but can also cause severe disease. Planktonic growth curves indicated that S. suis growth was enhanced in the presence of H. parasuis, while H. parasuis was at a disadvantage. It was also found that H. parasuis and S. suis biofilm biomass was decreased in co-culture. These effects were demonstrated to be partly attributable to secreted factors. Finally, H. parasuis protected S. suis from antibiotics in co-culture biofilms, and S. suis protected H. parasuis against swine complement proteins. The results here suggest H. parasuis and S. suis may increase each others’ virulence by preventing entrance into a quiescent biofilm form, as well as providing synergistic protection against antimicrobials and complement. A further understanding of the interplay between S. suis and H. parasuis could lead to the development of new approaches to reduce swine respiratory disease. Advisors/Committee Members: MacInnes, Janet (advisor).