|MCCAIG, WILLIAM - Orise Fellow|
|KUEHN, JOANNA - Iowa State University|
|PHILLIPS, GREGORY - Iowa State University|
Submitted to: Pasteurellosis in Production Animals International Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/20/2014
Publication Date: N/A
Technical Abstract: Haemophilus parasuis is the cause of Glässer’s disease in swine, which is characterized by systemic infection resulting in polyserositis, meningitis, and arthritis. An enormous difference exists in the severity of disease caused by H. parasuis strains, ranging from lethal systemic disease to asymptomatic carriage. To identify differences in genotype that could account for virulence phenotypes, genome sequencing was performed on 10 H. parasuis strains (Nagasaki, 12939, SW140, 29755, MN-H, 84-15995, SW114, H465, D74, and 174). Virulence of these 10 strains was evaluated using an intranasal challenge in caesarian-derived, colostrum-deprived (CDCD) pigs. H. parasuis strains Nagasaki, 12939, SH0165, SW140, 29755, and MN-H exhibited a high level of virulence as all pigs challenged with these strains developed clinical signs consistent with Glässer’s disease between 1-7 days post challenge, although there were some distinctions among these groups. H. parasuis strains 84-15995 and SW114 were moderately virulent, in that approximately half of the pigs in each group developed Glässer’s disease. H. parasuis strains H465, D74, and 174 were minimally virulent or avirulent in the CDCD pig model. Initial comparative genomic analysis of the different strains has identified several significant differences in coding regions. These coding regions include predicted outer membrane, metabolism, and adhesin related genes, some of which likely contribute to differences in virulence and systemic disease. Reports have been mixed as to the degree of heterologous protection afforded among strains. In subsequent studies prior exposure to strain SW114 protected pigs against disease with strain 12939; however, prior exposure to strain 174 only partially protected pigs from disease with strain Nagasaki, indicating cross-protection may be strain dependent. These studies will be useful for identifying H. parasuis virulence factors and potential cross-protective vaccine targets.