Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: June 5, 2005
Publication Date: June 5, 2005
Citation: Brockmeier, S., Loving, C.L., Nicholson, T.L., Palmer, M.V. 2005. Coinfection with porcine respiratory coronavirus and bordetella bronchiseptica in pigs. American Society for Microbiology. Z016, p. 614.
Coinfection with two or more pathogens is a common occurrence in respiratory diseases of most species. The manner in which these pathogens interact is not always straightforward, however. Bordetella bronchiseptica and porcine respiratory coronavirus (PRCV) are respiratory pathogens of pigs whose relatives, B. pertussis and the SARS virus, cause respiratory disease in humans. The effect of coinfection of PRCV and B. bronchiseptica was examined in thirty, 4-week-old pigs (10 pigs per group) that were infected with PRCV, B. bronchiseptica, or PRCV and B. bronchiseptica. An additional 10 pigs served as sham infected controls. Five pigs from each group were euthanized at 4 and 10 days post infection. In the two groups which were infected with virus, PRCV was isolated from the lung lavage of pigs at 4 days post infection but not at 10 days post infection. However, lung lesions were present at both time points and were more severe at 10 days post infection in these two groups. In both groups infected with the bacteria, B. bronchiseptica was cultured from all pigs at both 4 and 10 days post infection. Gross and histopathological lung lesions were more severe in the coinfected group as compared to the groups infected with B. bronchiseptica or PRCV alone. The difference was most pronounced at 10 days post infection, when the mean percentage of lung affected in the coinfected group was 19 percent compared to 5.5 percent and 1.4 percent for the groups infected with PRCV or B. bronchiseptica alone, respectively. Thus, there appears to be a synergistic effect between PRCV and B. bronchiseptica with regards to severity of pneumonia in swine, although the fact that the most severe lesions occurred when the pathogens were being cleared may indicate that the lesions are due to the immune response to the pathogens rather than the presence of the pathogens themselves.