Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 21, 2000
Publication Date: N/A
Interpretive Summary: Bordetella bronchiseptica causes swine atrophic rhinitis and pneumonia, tracheobronchitis in dogs, and bronchopneumonia in many species, including rabbits, guinea pigs, cats, and horses. During the 1980's it was also implicated as a respiratory pathogen in seals. In the past, no procedure was available that could easily be used to differentiate between strains of fB. bronchiseptica. Recently we demonstrated that a technique known as ribotyping, which reveals variations in the DNA of different isolates, could be used to classify strains of B. bronchiseptica obtained from different hosts. The significance of this technique is that it permits the tracking of transmission patterns within and between groups of infected animals. In this study we determined the ribotype of 35 seal isolates that were obtained from common and gray seals in the North Sea, during and after a respiratory disease epidemic in Great Britain and Europe that began in 1988. All seal isolates had an identical ribotype that has not previously been found in any of the 214 other B. bronchiseptica isolates we have examined, acquired from 11 different non-marine mammalian hosts at locations all over the world. The seal isolates were also identical when their DNA was analyzed by a second technique known as restriction endonuclease analysis. This is the first report characterizing B. bronchiseptica isolates from sea mammals. We conclude that a single clone of B. bronchiseptica, not found in land mammals, is circulating within the seal population of the North Sea. This work further demonstrates the usefulness of ribotyping for differentiating B. bronchiseptica strains and for establishing transmission patterns of this organism.
Technical Abstract: Bordetella bronchiseptica is a common mammalian respiratory. During a recent European phocine morbillivirus outbreak, B. bronchiseptica was identified as a secondary pathogen causing tracheitis and bronchopneumonia. There is currently no genetic information available from phocine isolates upon which definitive epidemiologic studies could be based. The goal of the present study was to characterize, by ribotyping and restriction endonuclease analysis (REA), 35 phocine B. bronchiseptica isolates and to ascertain their relationship to one another and to isolates acquired from other host species. Thirty-four isolates were obtained in Scotland; the remaining isolate was obtained independently in Denmark. All displayed an identical Pvu II ribotype unique from the 18 ribotypes previously detected in strains from heterologous hosts. Alternative restriction enzymes, useful for subgrouping strains within Pvu II ribotypes, also failed to discriminate among phocine isolates. The exclusive occurrence of a single ribotype of B. bronchiseptica in a particular host species has not been previously observed. Similarly, REA based on either Hinf I or Dde I profiles did not reveal detectable polymorphisms, although unique patterns were readily distinguished among a limited number of isolates from other host species. This is the first report demonstrating the utility of REA using frequently cutting enzymes for discrimination of B. bronchiseptica strains. These data suggest that B. bronchiseptica-induced respiratory disease in seals along the Scottish shore may be due to the circulation of a single, unique clone.