Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: October 15, 1997
Publication Date: N/A
Bordetella bronchiseptica is an etiologic agent of swine atrophic rhinitis and pneumonia. Serum resistance has been reported as a virulence factor for the related human pathogen Bordetella pertussis. The genetic locus brk was shown to be required for this phenotype, and brk sequence has been demonstrated in one strain of B. bronchiseptica. We found by Southern blotting that 18 B. bronchiseptica swine isolates contain sequence homologous to the B. pertussis brk locus. Two of these isolates were tested for serum resistance. Bacteria were incubated for 30 minutes at 37 deg C in 50% serum from rabbits hyperimmunized with B. bronchiseptica, supplemented with guinea pig complement. Survival ranged from 85-100% as compared to bacteria incubated in phosphate buffered saline (PBS). Survival of E. coli incubated under similar conditions in the presence of specific antibody was <0.0001%. An additional swine isolate that appeared to have a deletion in the region homologous to brk had a reduced level of serum resistance (roughly 34% survival). These results indicate that serum resistance may be a virulence factor for B. bronchiseptica and that this phenotype may be mediated by the brk locus.