The host's immune system is the primary defense against pathogens. The innate immune response provides the first line of defense through physical barriers, phagocytosis, and the production of antimicrobial peptides. If pathogens breach these defenses, the adaptive immune response, including B cells and T cells, is activated to target specific pathogens. However, some pathogens have evolved mechanisms to evade immune detection, making infections more severe or chronic.
