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

Four strains of Bordetella bronchiseptica (CSU-P-1, 64-C-0406, 1120-A-83-013, and B205BT) with defined virulence for neonatal swine were examined, and an attempt was made to correlate the presence of certain in vitro phenotypic characteristics with the ability of a particular B. bronchiseptica strain to produce turbinate and lung lesions in piglets. All of the strains except CSU-P-1 colonized the nasal passages of the pigs heavily, and strains 1120-A-83-013 and B205BT produced moderate to severe nasal and lung lesions in experimentally infected piglets. All of the strains attached equally well to porcine tracheal ring explant cultures, and all of the strains except CSU-P-1 produced smooth, hemolytic colonies on Bordet-Gengou medium, agglutinated porcine erythrocytes, and possessed adenylate cyclase activity. Strains 1120-A-83-013 and B205BT produced considerably higher levels of dermonecrotic toxin activity than did strains CSU-P-1 and 64-C-0406. These results indicate that production of nasal and lung lesions in neonatal piglets by the B. bronchiseptica strains tested can be directly correlated with their level of dermonecrotic toxin production.