Final answer:
Pathogens, such as viruses and Mycobacterium tuberculosis, employ strategies like masking their antigens with host molecules or developing complex cell walls to evade the host's immune response and ensure their survival. Evasion tactics also include antigenic variation, production of protective capsules, and immune suppression, allowing chronic infections and challenging the effectiveness of interferons without robust cytotoxic T cell response.
Step-by-step explanation:
Pathogens have developed various mechanisms to evade the immune response, which is critical for their survival and proliferation within the host. One strategy employed by pathogens like viruses is to mask their antigens with the host's molecules. For instance, HIV uses the plasma membrane of the host cell to conceal its own antigens, thereby avoiding detection and destruction by the host's immune system.
Another example is Mycobacterium tuberculosis, which has a complex cell wall that resists the digestive enzymes of macrophages. Pathogens may also vary their surface antigens or produce protective capsules. These adaptations ensure that pathogens can persist within the host, leading to chronic infections like tuberculosis.
Moreover, some helminthic worms use glycan molecules to mimic host cells or suppress the immune system altogether. Interferons have a role in slowing viral replication in diseases such as hepatitis B and C, but a robust cytotoxic T cell response is crucial for overcoming viral infections through clonal expansion and the killing of infected cells.