Immune evasion and subversion pt 2 Flashcards
T and B cells bearing receptor that recognize self-antigens are eliminated
clonal deletion
T-Cells clonal deletion
-must bind to MHC but not self antigen
-Fails to recognize self MHC eliminate
-Passes but does not react well with self-antigen it will be eliminated
Schistosome mansoni outer covering
tegument
Schistosome mansoni taking advantage
It takes adavtange of nonresponse to self by absorbing host proteins onto their tegument to make it look like it apart of own tissue
T. vaginalis taking advantage
Encodes surface in proteins that are similar to the host proteins so it does not trigger a strong immune response
Straegy used by parasties to evade the host’s immune system by altering the proteins or antigens on their surface
Antigenic variation
Trypanosoma brucei using variant surface glycoprotein
Have over a thousand copies of VSG but only express 1 at a time
VSG into the membrane and a variable region exposed to antibodies
Antigenic Variation works
Pseudogene are inactive due to the lack of promoters
Only one site is expresses at a time
Then a new VSG gene is copied from the pseudogene pool and transposed into the expression site
How does this affect antibodies
Antibodies from previous VSG proteins become ineffective
How often does antigenic switich occur
about every 100 generations
How does antigenic variation affect immune response
Allows parasite to avoid detection by immune cells targeting specific antigens
Allows for reinfection of previously infected hosts