



Infection is a tug-o-war your immune cells and pathogens are fighting constantly. Immune cells are your fellowship, the ring wraiths and the orcs are the pathogens, and both are fighting for the ring (control over the host cell). Just as in Lord of the Rings, at some moments Sauron has the upper hand and other moments the fellowship rises to the top – but the battle is always unfinished.

In order for the pathogen, a mere tiny bacterium, to gain leverage during infection against highly prepared immune cells, they must evolve to be stealth and well-equipped for battle. Specifically, intracellular pathogens, which replicate within host cells, have evolved survival strategies to evade host antimicrobial mechanisms by modulating, or taking control, of these mechanisms.

Some intracellular bacteria, like Brucella abortus, replicate within host membrane-bound vacuoles, or enclosed intracellular compartments. After host cells engulf bacteria from the extracellular milieu, the bacteria within the bacteria-containing vacuole (BCV) are recognized as foreign invaders and can be redirected for degradation by autophagy.

Autophagy has earned its right to be a current buzzword due to its inherent badassedness. Autophagy is an intracellular process of capture and destroy (by lysosomal degradation, explained below) of damaged organelles, protein aggregates, and cytosolic content. However, in the last few years autophagy has been identified to be an important player in innate immunity, or capture-and-destroy-pathogen-immunity.