viral evasion of host immunity Flashcards
give a way in which herpes simplex virus can evade the immune system
makes ICP 47 protein
stops tap from allowing peptide entering endoplasmic reticulum and therefore prevents it from being picked up by MHC and presented on the cell surface
how does the epstein barr virus evade the immune system
EBV- produces EBNA1 a protein containing lots of glyciens - this cannot be processed by proteasome
how does the cytomegalovirus evade the immune system?
produces US3 protein which binds to tapasin and prevents peptides from being loaded onto MHC
how does adenovirus evade the immune system?
produces E3-19K which prevents recruitment of TPA to tapasin and also retains the MHC in the ER
how does the KSHV virus evade the immune system?
kK3 protein induces polyubiquitination and internalisation of the MHC
MHC in the internalised endosomes are degraded by lysosomes
what is the problem with the viral mechanism to stop MHC surface presentation?
and what is a mechanism viruses have developed to avoid this?
if the cell does not have any MHC molecules on the cell surface then it wont be targeted by T cells but it will be targeted by NK cells as they will recognise the cell as abnormal.
viruses encode MHC analogues which are presented on the cell surface and tricks the NK cells
how does the measles virus cause immunosuppression?
infects CD150 (SLAM) positive cells which includes memory T cells which erases the immunological memory
what is a way a virus avoids the humeral immune response
antigenic variation
slight changes in viral antigen so any antibodies already made against the virus will no longer recognise it when next infected by that virus
eg influenza antigenic drift
influenza antigenic shift- massive change in virus introduced by different animal sources
what is a way vaccines are being designed to reduce problems with viral antigeninc shifting
vaccines that persuade the immunesystem make antibodies to a more inaccessible area of the antigen that has less frequent mutagenic changes than the top part of the virus
synthetic vaccinology
what is antibody dependent enhancement? for example with dengue
After a person is infected with dengue, they develop an immune response to that dengue subtype. … The immune response attracts numerous macrophages, which the virus proceeds to infect because it has not been inactivated. This situation is referred to as Antibody-Dependent Enhancement (ADE) of a viral infection
