Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 28, 1998
Publication Date: N/A
Technical Abstract: Bordetella bronchiseptica undergoes phenotypic modulation depending on the temperature at which it is cultured. When cultured at 37C many virulence factors are expressed, whereas they are not when cultured at 23C. Total attachment and intracellular survival of B. bronchiseptica cultured at 23C under modulating conditions or at 37C under non-modulating conditions were determined for several cell types. Cell types used included porcine alveolar macrophages, J774 cells (mouse macrophage cell line), HeLa cells (human carcinoma cell line) and PK-15 cells (porcine kidney cell line). Cells were co-incubated with bacteria for 1 hour after which excess bacteria were washed away and one set of cells was lysed so total number of viable extracellular and intracellular bacteria associated with the cells could be determined. Media containing polymyxin B was added to another set of cells to kill extracellular bacteria and after washing, these cells were ealso lysed to determine viable intracellular bacteria. Trends with all cell types were similar. More bacteria cultured at 23C were associated with cells than bacteria cultured at 37C, but there were more bacteria cultured at 37C surviving intracellularly than bacteria cultured at 23C. When using a double-fluorescence staining procedure to distinguish intracellular bacteria from extracellular bacteria, it appeared that more bacteria grown at 23C were both intracellular as well as extracellular. Thus apparently these bacteria are internalized but do not survive.