Question

In detail, what are the mechanisms bacteria use to avoid the host immune system ?

Answer 1

The bacteria are able to avoid the host immune system and there are many ways using which the bacteria does that. There is antigenic variation which allows the bacteria to do that and helps in escaping the immunity. It can do by altering the antigens and is mostly applicable for extracellular pathogens. The antigenic types of different types and can be identified by the serological tests and called serotypes. Once that particular organism infects, the body develops a type specific immunity which protects against reinfection with same type of organism.

There is another angle also for antigenic variation where at one single virus type is responsible for most infections and the human popular gradually tends to develop a protective immunity against them. It does so by neutralizing antibody against the infectious agent.

Some of the strategies applied by bacteria :

Molecular Mimicry – The organism tends to mimic itself like a part of the body and hence avoids any kind of invasion by the host immune system. This does not let formation of the antibodies against the micro-organism. The bacteria tends to mimic the genetic material of the host body and remain the host without have an immune response triggered against it.