Virulence of Bordetella Bronchiseptica in the Porcine Respiratory Tract

Abstract

SUMMARY.The virulence of Bordetella bronchiseptica in gnotobiotic piglets was studied by intranasal infection with 11 cultures derived from eight strains isolated from pigs (4), dogs (2), a human subject and a monkey. Six of the cultures contained organisms in phase I and five contained phenotypically different phase-I11 or -1V organisms. Of the phase-I11 and -1V cultures, four were derived from strains that had been isolated in phase I. Colonisation of the nasal cavity was investigated by counting bacteria in nasal swabs and washings. The toxigenicity of cell extracts from each strain and variant was determined by tests of lethality in mice or of cytopathogenicity in cell cultures. The results showed that two phase-I cultures from pigs colonised the nasal cavity and respiratory tract of gnotobiotic piglets better than did four phase-I cultures from other species. Phase-I organisms invariably produced capsules, fimbriae and mannose-resistant haemagglutination of guinea-pig erythrocytes. Four of five cultures in phases I11 and IV consisted of organisms that did not produce capsules, fimbriae or haemagglutination and colonised the nasal cavity poorly. Phase variation from I to I11 occurred in culture and in vivo, but variation from I11 to I occurred in vivo only and was accompanied by enhanced colonisation. Gnotobiotic piglets infected with porcine phase-I organisms exhibited atrophy of the nasal turbinate bones after 28 days; these organisms produced significantly more toxin than did bacteria in phase I from other species, or those in phases 111 and IV. It was concluded that the development of turbinate atrophy was associated with (1) the ability to produce heavy, persistent colonisation in the nasal cavity, and (2) the production of a heat-labile toxin. Only the two porcine phase-I cultures possessed both properties.

The use of pulsed-field gel electrophoresis to examine the epidemiology of Bordetella bronchiseptica isolated from cats and other species

“…These results suggest that B. bronchiseptica is an opportunistic pathogen of cats, and that the likelihood of a particular B. bronchiseptica isolate producing disease is probably related to host or environmental factors such as crowding, stress and hygiene [36]. It may also be related to differential expression of virulence determinants as has been demonstrated for canine or porcine infections where phase variation occurs [37,38].…”

A highly adherent phenotype associated with virulent Bvg+-phase swine isolates of Bordetella bronchiseptica grown under modulating conditions

“…It follows, therefore, that the specific mechanisms used for adherence by these two pathogens may differ. Additionally, strains of B. bronchiseptica isolated from a specific host often display a reduced ability to colonize or induce disease in heterologous species (11,25,37), suggesting there may be host-specific differences in colonization factors of B. bronchiseptica strains as well. Thus, studies on adhesion of B. bronchiseptica in a particular host species are most meaningful when performed with relevant target cells from that species.…”

Virulence factors of Bordetella bronchiseptica associated with the production of infectious atrophic rhinitis and pneumonia in experimentally infected neonatal swine

“…Other investigators have also noted a positive correlation between DNT activity or mouse lethality of B. bronchiseptica strains and the ability of those strains to produce respiratory disease in pigs (4, 6). Collings and Rutter (4) noted that strains of B. bronchiseptica which produced turbinate atrophy in experimentally infected piglets had a much lower 50% lethal dose in mice than did avirulent strains. Elias et al (6) demonstrated that B. bronchiseptica strains isolated from herds of pigs suffering from IAR had a considerably higher average level of mouse toxicity than did strains isolated from nonaffected herds.…”

“…There appears to be considerable variation among B. bronchiseptica strains in their ability to colonize and produce turbinate atrophy and pneumonic lesions in young pigs (4,24). This situation has important implications in the treatment of commercial pig herds colonized by B. bronchiseptica.…”