A PORCINE MODEL FOR THE EVALUATION OF VIRULENCE OF BORDETELLA-BRONCHISEPTICA

Studies of virulence factors of Bordetella bronchiseptica require a su itable system. Such a system was devised in colostrum-deprived, caesar ean-derived pigs, aged 7 d. In two different experiments, pigs (n=11) were inoculated intranasally with 10(6) colony-forming units of the vi rulent strain 4609. In the same way: further pigs (n=11) were inoculat ed with a strain (B 133) of unknown virulence. No significant differen ces between 4609 and B133 colonization were seen. However, colonizatio n of the turbinates was significantly higher than that of the trachea, lung and tonsil, and a significantly higher degree of colonization wa s present at 11 d post-inoculation (PI) than at 15 days. Moderate turb inate atrophy was present by 11 d PI, and peribronchiolar fibrosis was present at 15 days. Immunocytochemical methods showed that all pigs h ad bacterial antigen in the ciliated cells of the turbinates and trach ea, and in the lung; some pigs also had antigen in the bronchi. Bacter ial antigen was present in some bronchioles and within the cytoplasm o f pulmonary macrophages and neutrophils. This model should prove usefu l for comparing strains of B. bronchiseptica and isogenic mutants defi cient in putative virulence factors. (C) 1997 W.B. Saunders Company Li mited.