Molecular interactions of Pasteurellaceae from porcine tonsil

点击翻译按钮获取中文摘要

***In many animals, tonsils play a significant role in the host immune response by acting as a first defence against antigens entering the upper respiratory and gastrointestinal tracts. Paradoxically, they are also an important site of colonisation of many organisms and can act as a portal of entry for a number of important pathogens. Haemophilus parasuis and Streptococcus suis are two bacterial species found in the tonsil of the soft palate of almost all pigs. They often persist without causing any problems, but depending on the strain and unknown factors, these organisms can invade and cause fatal diseases such as septicaemia and meningitis. Numerous studies have been done to try to identify mechanisms of pathogenesis and virulence factors of these two species, but especially in the case of H. parasuis, no factors such as toxins have been identified that explain the observed pathology. There is growing evidence, however, that the virulence of bacterial pathogens may be increased in co-infections. ***Recent studies in our laboratory have revealed that many phenotypes including growth rate and resistance to serum and antibiotics are altered when S. suis and H. parasuis are grown together. Over the next 5 years we plan to characterize the interactions of additional strains of selected serovars of H. parasuis and S. suis grown in co-culture in media that begin to mimic in vivo conditions (e.g. with serum, saliva, antibiotics). We will also make fluorescently tagged stains of H. parasuis and S. suis and investigate the nature of dual species biofilms by laser scanning confocal microscopy. As well, the expression of selected virulence genes in mono-and co-cultures will be measured by qRT-PCR and global gene expression will be evaluated using RNA seq. In addition to these in vitro studies, we also plan to evaluate bacterial gene expression by qRT-PCR and RNA seq when mono and co-cultures are grown in the presence of swine cells using our ex vivo tonsil organ culture system and with primary tonsil epithelial cells. ***This work should provide novel insights into how important bacterial pathogens of the upper respiratory tract of swine interact and to how they can switch from begin commensals to invasive pathogens. In understanding these interactions, we hope to be able to identify targets for the development better treatment and prevention strategies that will lead to decreased antimicrobial usage and reduce the economic impact of H. parasuis and S. suis and other important bacterial pathogens of swine. **