How Salmonella overcomes body’s defences to cause disease ?
•the Vi antigen
– It forms a capsule to protect the bacterium from complement and from phagocytic(PMN) immune cells.
– the Vi antigen, further protect themselves from lysis within the macrophage
•The very presence inside the macrophages helps to escape the adverse conditions outside the macrophages
•they are protected from polymorphonuclear leukocytes (PMNs), the complement system, and the acquired immune response (antibodies)
•There are mechanisms which help the bacteria to overcome the hostile environment in side the macrophages
– The bacterium produces homocysteine to inactivate nitric oxide and enzymes
•The infected macrophage provides Salmonella a vehicle safe from other elements of the immune system and in which it can multiply and travel.
•The microorganism causes the apoptosis in the macrophages and enters the bloodstream to attack the rest of the body.
•M cells are epithelial cells that mature into professional phagocytes reside within Peyer's patches. Immobile and interspersed among regular enterocytes in Peyer patches,
•bacteria-mediated endocytosis (BME).helps to overcome the innate defenses in the small intestine