Anaplasma Phagocytophilum - Bacterial Mechanism

Bacterial Mechanism

Anaplasma phagocytophilum binds to fucosylated and sialylated scaffold proteins on neutrophil and granulocyte surfaces. A type IV secretion apparatus is known to help in the transfer of molecules between the bacterium and the host. The most studied ligand is PSGL-1 (CD162). The bacterium adheres to PSGL-1 (CD162) through 44-kDa major surface protein-2 (Msp2). After the bacterium enters the cell, the endosome stops maturation and does not accumulate markers of late endosomes or phagolysosomes. Because of this, the vacuole does not become acidified or fused to lysosomes. A. phagocytophilum then divides until cell lysis or when the bacteria leave to infect other cells.

This bacterium has the ability to affect neutrophils by altering the function of the host cell. It can survive the first encounter with the host cell by detoxifying superoxide produced by neutrophil phagocyte oxidase assembly. It also disrupts normal neutrophil function, such as endothelial cell adhesion, transmigration, motility, degranulation, respiratory burst, and phagocytosis. It causes an increase in the secretion of IL-8, a chemoattractant that increases the phagocytosis of neutrophils. The purpose of this is to increase bacterial dissemination into the neutrophil.