Evasion of host cell defense mechanisms by pathogenic bacteria

From an immunological viewpoint, invasion of pathogenic bacteria into a sus ceptible host poses a potential life-threatening situation and thus has to be met with all weapons that are available, A crucial component of host def ense mechanisms is the macrophage. The scavenger activity of this cell ensu res the uptake and destruction of bacteria in phagolysosomes, on the one ha nd, and activation of the adaptive component of the immune system through p resentation of bacterial antigens, on the other hand. From the bacterial pe rspective, entry into a phagolysosome is usually fatal and many pathogens h ave developed strategies that circumvent the destructive environment of thi s organelle. Such evasion strategies often exploit normal host cell functio n. Understanding these survival strategies will deepen our insight of the p athogenesis of infection as well as host cell biology.