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Virulence and Draft Genome Sequence Overview of Multiple Strains of the Swine Pathogen Haemophilus parasuis

Susan L. Brockmeier, Karen B. Register, Joanna S. Kuehn, Tracy L. Nicholson, Crystal L. Loving, Darrell O. Bayles, Sarah M. Shore, Gregory J. Phillips
Plos One 2014 v.9 no.8 pp. e103787
DNA, Haemophilus parasuis, adhesins, animal pathogenic bacteria, arthritis, bacterial infections, disease severity, genes, genomic libraries, genomics, genotype, meningitis, metabolism, models, morbidity, mortality, nucleotide sequences, phenotype, sequence analysis, swine, swine diseases, vaccines, virulence
Haemophilus parasuis is the cause of Glässer’s disease in swine, which is characterized by systemic infection resulting in polyserositis, meningitis, and arthritis. Characterization of this animal disease is complicated by the enormous differences in the severity of disease caused by H. parasuis strains, ranging from lethal systemic disease to subclinical carriage. To identify differences in genotype that could account for virulence phenotypes, we established the virulence of, and performed whole genome sequence analysis on, 11 H. parasuis strains, 10 of which were sequenced as part of this study. Virulence was assessed by evaluating morbidity and mortality following intranasal challenge of caesarian-derived, colostrum-deprived (CDCD) pigs. Genomic DNA from strains Nagasaki, 12939, SW140, 29755, MN-H, 84-15995, SW114, H465, D74, and 174 was used to generate Illumina paired-end libraries for genomic sequencing and de novo assembly. H. parasuis strains Nagasaki, 12939, SH0165, SW140, 29755, and MN-H exhibited a high level of virulence. Despite minor distinctions among these groups, all pigs challenged with these strains developed clinical signs consistent with Glässer’s disease between 1-7 days post-challenge. H. parasuis strains 84-15995 and SW114 were moderately virulent, in that approximately half of the pigs infected with each developed Glässer’s disease. H. parasuis strains H465, D74, and 174 were minimally virulent or avirulent in the CDCD pig model. Comparative genomic analysis among strains identified several noteworthy differences in coding regions. These coding regions include predicted outer membrane, metabolism, and pilin or adhesin related genes, some of which likely contributed to the differences in virulence and systemic disease observed following challenge. These data will be useful for identifying H. parasuis virulence factors and vaccine targets.