Interactions between bovine endothelial cells and Pasteurella multocida: association and invasion.

We investigated the association and the invasion of a bovine aortic endothelial cell (BAEC) line by Pasteurella multocida to study the potential role of internalized bacteria and possible intracellular survival during Pasteurella infections. Our data indicate that P. multocida is able to adhere to and to invade BAECs. The density of the bacterial population plays a defined role for an optimal mechanism of interaction between bacteria and cells, as does the incubation period of association and invasion. The optimal bacteria/cells ratio was found to be 100/1, while the optimal infection time was approximately 4 h of incubation. Bacterial internalization was dependent on microfilament and microtubule stability. The invasion ability of P. multocida in the presence of cytochalasin D was reduced by 60%; in the presence of colchicine it was reduced by 97% and in the presence of nocodazole it was reduced by 95%. Our data show that internalized P. multocida did not induce mortality of invaded endothelial cells. Some Pasteurella cells were able to survive and undergo exocytosis.