Question

In your own words be as specific and detailed. explain how the trypanosome survive within the host to ensure transmission to new hosts? How does the parasite evade the host immune system?

Answer 1

The adaptive host immunity allows trypanosomes to survive and establish chronic infection. The trypanosome sustains itself for long term in mammalian hosts and ensure transmission to new host. The trypanosome need to gain salivary gland access to ensure their transmission to the new host.

The parasite evade the host immune system by the mechanism of antigenic variation.

1. The genome of trypanosome has a cassette of 1000 genes that code for variant surface glycoproteins VSGs.

2. A single VSG gene is expressed when it is switched into an active site close to the telomer. The remaining genes are silent.

3. This mechanism allows the parasite to change its surface protein coat when an immune challenge is raised against the current array thus, proonging its existence in host cells.