immuunivastus

Immuunivastus, also known as immune evasion, is a process by which pathogens, including viruses, bacteria, and parasites, manipulate the host's immune system to avoid detection, elimination, or destruction. This strategy allows the pathogen to persist within the host, often leading to chronic infections. Immune evasion can occur at various stages of the immune response, including antigen presentation, signal transduction, and effector functions.

One common mechanism of immune evasion is the modification of surface antigens, such as glycoproteins or glycolipids, to prevent recognition by host immune cells. For example, viruses like HIV and hepatitis C virus (HCV) encode enzymes that modify host cell surface proteins, making them less recognizable to the immune system.

Another strategy involves the inhibition of immune cell activation and proliferation. Pathogens can achieve this by producing immunosuppressive molecules, such as cytokines, or by interfering with immune cell signaling pathways. For instance, Mycobacterium tuberculosis produces mycolic acids that inhibit phagosome-lysosome fusion, preventing the bacterium from being destroyed by macrophages.

Some pathogens also exploit the host's immune cells to their advantage. For example, certain bacteria, like Legionella pneumophila, can survive and replicate within phagocytic cells, such as macrophages, without being killed. This intracellular lifestyle allows the pathogen to avoid immune detection and destruction.

Immune evasion is a complex and dynamic process that involves a delicate balance between the pathogen and the host immune system. Understanding the mechanisms of immune evasion is crucial for the development of new therapeutic strategies to combat infectious diseases.