cells of the innate immune system—macrophages, neutrophils, and monocytes—are constantly surveying the body to find signs of injuries and infections. Once such an infection is detected, these cells swarm to the infected site to ingest, or phagocytose, bacterial cells or the viral particles. They devour the invaders, internalize them, and route them to special compartments. These compartments—lysosomes, among them—are chock-full of enzymes to degrade the virus into smaller fragments, including those bits and pieces of proteins known as peptides.
