Final answer:
Bacillus anthracis evades phagocytosis by producing virulence factors encoded by two plasmids. These factors suppress the immune system and provide protection from the host immune response.
Step-by-step explanation:
Bacillus anthracis, the causative agent of anthrax, evades phagocytosis through the production of virulence factors. It maintains two plasmids, pX01 and pX02, which encode these factors. The pX01 plasmid encodes a three-part toxin that suppresses the host immune system. The pX02 plasmid, on the other hand, encodes a capsular polysaccharide that protects the bacterium from the host immune system.
By producing these virulence factors, Bacillus anthracis is able to avoid being ingested by phagocytes, allowing it to persist and cause infection in the host.