Final answer:
Bacterial capsules function primarily to avoid phagocytosis by acting as a barrier and making the cellular structure too large for phagocytes to ingest. Other virulence factors include proteases that degrade antibodies, and changes in surface proteins to hinder the activity of complement molecules.
Step-by-step explanation:
One of the main functions of capsules in bacteria is to avoid phagocytosis. This is a form of immune evasion where the capsule, often composed of polysaccharides, prevents immune cells from adhering and then engulfing the bacterial cell.
The encapsulation makes the bacterial cell much larger and hence, more resistant to being phagocytosed by phagocytes.
Name at least two ways that a capsule provides protection from the immune system. Firstly, the composition of the capsule acts as a physical barrier preventing adherence by phagocytes.
Secondly, the capsule enlarges the bacterium, making it harder for phagocytes to engulf it. In addition to capsules, bacteria use other virulence factors to evade the immune system.
One is the production of proteases, which break down host antibodies, thereby reducing their efficacy. Another is the alteration of the bacterial surface proteins, as seen in Streptococcus species, which contain M protein that inhibits the binding of complement molecules essential for phagocyte activity.