title: Comparative virulence of Haemophilus parasuis serovars 1 to 7 in guinea pigs.
abstract: Reference strains for Haemophilus parasuis serovars 1 to 7 were examined for virulence by inoculation of guinea pigs. Guinea pig response to intraperitoneal inoculation was similar for the 7 reference strains. However, apparent differences in virulence were detected after intratracheal inoculation. Cells of the references strains for serovars 1 and 5 were most invasive, causing moribundity or death at higher doses and a persistent septicemia at lower doses. Haemophilus parasuis could be isolated from respiratory and systemic sites; purulent bronchopneumonia, pericarditis, and pleuritis were apparent in infected guinea pigs. Inoculation of cells of the reference strains for serovars 2 and 6 also resulted in bronchopneumonia and moribundity or death in some guinea pigs; however, reisolation of H parasuis and microscopic lesions at necropsy were less pronounced than those observed with serovars 1 and 5. Inoculation of cells of serovars 3, 4 and 7 induced only transient clinical signs and minimal evidence of H parasuis infection at necropsy. The data from intratracheal inoculation of guinea pigs are similar to data from other investigations in swine, indicating differences in the pathogenic potential of H parasuis strains. Thus, guinea pigs may be useful as a laboratory animal model for examining cellular factors associated with virulence and immunogenicity of H parasuis.
authors.affiliation: Department of Veterinary and Microbiological Sciences, College of Agriculture, North Dakota State University, Fargo 58105.
authors.forename: V J
authors.initials: VJ
authors.lastname: Rapp-Gabrielson
authors.forename: D A
authors.initials: DA
authors.lastname: Gabrielson
authors.forename: G J
authors.initials: GJ
authors.lastname: Schamber
mesh_terms: D000818:Animals; D001170:Arthritis, Infectious / Q000382:microbiology / Q000662:veterinary; D016667:Bacterial Capsules; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D005260:Female; D006168:Guinea Pigs; D006190:Haemophilus / Q000145:classification / Q000472:pathogenicity*; D006192:Haemophilus Infections / Q000382:microbiology / Q000662:veterinary*; D012692:Serial Passage; D012700:Serositis / Q000382:microbiology / Q000662:veterinary; D012703:Serotyping; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*; D014774:Virulence