This document discusses factors of pathogenicity and virulence in pathogens. It covers an pathogens' ability to (1) overcome the innate immune system by resisting complement activation and phagocytosis, and (2) overcome the acquired immune system by avoiding antibodies/lymphocytes through rapid reproduction, immune deception, antigen variability, and immune suppression. It also discusses the toxicity pathogens can cause through direct cellular damage, metabolic injury from exotoxins, and damage from the host's inflammatory and immune responses.