Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: February 17, 1995
Publication Date: N/A
The known adhesins of virulent B. bronchiseptica strains are expressed only in the Bvg+ phase following incubation at 37 deg. C. However, the temperature at the initial site of colonization on the mucosa of the upper respiratory tract is significantly less than 37 deg. C. Furthermore, B. bronchiseptica has been shown to survive in environments at low temperature. These observations suggest that organisms initiating infection are likely to have a phenotype different from those grown at 37 deg. C. We compared the adherence of virulent porcine strains grown at 37 deg. C with their Bvg- phase counterparts grown at low temperature. While cultures grown at 37 deg. C attached well to swine ciliated nasal epithelial cells (approx. 8 bacteria per cells, depending on the strain), their Bvg- phase counterparts grown at 23 deg. C exhibited a 2- to 3-fold incerease in the number of bacteria attached per cell. Temperature shift experiments revealed that the level of attachment of Bvg- phase organisms steadily declined with increasing incubation time at 37 deg. C. As demonstrated by Western blotting, cultures grown at 23 deg. C did not produce filamentous hemagglutinin or pertactin until at least 8 to 10 hours after a shift to 37 deg. C. These data suggest that a novel Bvg-repressed or temperature-dependent adhesin may be important in initiation of porcine B. bronchiseptica infection.