Viruses must survive inside the host. The immune system tries to detect and destroy them. Many viruses therefore use special strategies to escape this defence.
Some viruses hide their genetic material. They stay inside cells in a quiet or latent state. In this way, they reduce the signals that would alert immune cells.
Other viruses block the production of interferons. Interferons normally warn nearby cells and slow viral spread. By interfering with this signal, the virus gains time to multiply.
Several viruses also interfere with antigen presentation. They prevent infected cells from displaying viral proteins on their surface. As a result, cytotoxic T cells find it harder to recognise and kill those cells.
Some viruses produce proteins that look like host molecules. These decoys confuse immune receptors. They can reduce inflammation or block the action of antibodies.
A few viruses attack immune cells directly. They infect lymphocytes or macrophages and weaken the response from within. HIV is a well-known example of this approach.
Viruses also change their surface proteins over time. This antigenic variation helps them avoid antibodies made against earlier forms. Influenza viruses use this method every season.
These evasion strategies explain why some infections persist. They also show why vaccines and antiviral drugs must target more than one step of the viral life cycle. Understanding these tactics remains essential for better treatment and prevention.
CMP Bio World 