Cell-mediated immunity is directed primarily at microbes that survive in phagocytes and microbes that infect non-phagocytic cells. It is most effective in removing virus-infected cells but also participates in defending against fungi, protozoans, cancers, and intracellular bacteria.Nonetheless, the antibody may be effective against E. Chaffensis when a threshold portion of the microbial pool is extracellular and accessible to antibody. This discovery suggests that other obligate intracellular pathogens may also have extracellular phases during which they are susceptible to humoral immunity.