Evasion and Subversion of Immune System (Lec 9) Flashcards
1
Q
antigenic drift
A
- Point mutations lead to changes in surface proteins (antigen)
- gradual, small changes in the genetic makeup of a virus, particularly in its surface proteins, that occur over time
e.g. yearly changes in influenza viruses
2
Q
antigenic shift
A
- sudden, major change in the antigens of a virus, often leading to the emergence of a new strain that the immune system has not encountered before
- Recombination: co-infection results in an exchange of genetic information and generates more competitive virus
- has resulted in influenza pandemics
e.g. Spanish Flu- H1N1 (1918)
3
Q
Staphylococcus aureus
A
- has a superantigen that prevents IgA mediated phagocytosis
- disrupts host immune response
4
Q
Superantigens
A
- cross-link receptors together to trigger broad T cell activation.
- Results in non-specific T cell
activation - less effective immune response
- trigger an overactive immune response by binding to a large number of immune cells and causing an exaggerated activation of the immune system
- can lead to harmful effects, including inflammation and tissue damage
5
Q
Gene Conversion of Trypanosoma brucei
A
- a protozoan parasite that has a
surface glycoprotein that can undergo gene conversion - > 1000 genes encoding variable
surface glycoproteins (VSGs), can help it evade immune response - can lead to Chronic infection = inflammation
- Inflammation = neurological
damage and coma, “sleeping
sickness”
6
Q
Latent Viruses
A
- hide from our immune system
- integrate DNA into host cells
- a trigger reactivates their replication
ex. Epstein-Barr (EBV) hides in B cells, can lead to cancer if reactivated
7
Q
Measles Infection and Immune Amnesia
A
- measles affects 2 key lines of immune response: naive cells and memory cells
- after infection, body is left vulnerable long after initial illness has passed
- diversity of naive cells is reduced
- wipes out proportion of the memory cells
