how microbes avoid immune system Flashcards
1
Q
how does yersinia pestis avoid immune system
A
- yersinia plasmid codes for injectisome
- injectisome punches a hole in membrane of target cell
- this allow infiltration of yop protein
- this cuases actin depolymerisation and inhibition of signal transduction
- inhibits phagocytosis
2
Q
how does stapylococcus aureus avoid immune system
A
- A proteins bind to antibodys
- prevent antibodys opsonising microbes
- inhibits phagocytosis
3
Q
what are three ways microbes can avoid innate immunity
A
- avoiding/ inhibiting phagocytosis
- avoiding complement
- avoiding cytokines
4
Q
how does mouse pox avoid cytokines
A
- produces soluble protein which can bind to cytokines
- this prevents cytokine binding to its receptor
- to combat this we can give antibodies which can bind to the soluble protein produced by the virus, this allows the cytokine to bind to its receptor
5
Q
what are the 3 mechanisms microbes can avoid the adaptive immune system
A
- antigenic variation
- antigen shift/drift
- active supression
6
Q
what is active supression
A
- certain microbes such as viruses can prevent MHC presentation
- e.g herpes simple virus has an immediate early gene which codes for a protein that binds to TAP and prevents entry of peptides in endoplasmic reticulum
- adenovirus- binds to mhc and retains it in the endoplasmic reticulum prevents mhc presentation
7
Q
how does trypanosoma brucei avoid immune system
A
- has surface variant glycoproteins on its surface
- over 1600 genes which codes for these variant surface glycoproteins
- only present one of these glycoproteins at a given time
- when host produces antibodies to the variant surface glycoprotein the parasite can change it to another type of variant surface gylcoprotein making the antibody incompatible
8
Q
how does influenza avoid the host immune system
A
- antigenic drift- mutations
-antigenic shift- gene reassortment giving rise to new strains of the influenza- happens upon co-infection of two influenza strains to one host cell - which is why new flu vaccines arise each year
9
Q
how does hiv avoid immune system
A
- antigenic drift- mutations result new strains of HIV to arise
- which is why its hard to develop a vaccine for HIV
10
Q
how does microbes avoid the complement
A
- capsule can inhibit binding of complement
