Evidence for the Pasteurella haemolytica cytotoxin as a product of actively growing bacteria.
The release of soluble cytotoxin from Pasteurella haemolytica type 1 cultured at 37 C in RPMI 1640 medium containing 7% bovine fetal serum was evaluated, using bovine alveolar macrophages in a microplate 51Cr-release assay. Heat-labile leukotoxic activity was detected in culture supernatant during the lag and logarithmic-growth phases, but not in stationary-phase culture; toxic activity could not be demonstrated in sonicates of logarithmic (1 hour) or stationary (18 hour) phase organisms. This pattern of toxin release, typical of a bacterial exotoxin or metabolic enzyme, is unique among bacterial leukotoxins, which are typically cell-associated and released after autolysis or sonication from outgrown cultures.
D000818:Animals; D002417:Cattle; D003470:Culture Media; D003603:Cytotoxins / Q000096:biosynthesis* / Q000633:toxicity; D006358:Hot Temperature; D008264:Macrophages / Q000187:drug effects; D010325:Pasteurella / Q000254:growth & development / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000166:cytology; D013010:Sonication
D003470:Culture Media; D003603:Cytotoxins