Week 6- Viral Immune Evasion Strategies Flashcards
What are the main ways antibodies fight viral infection?
Bind to viral attachment proteins Destabilize viral structures Opsonization viruses for phagocytosis Cause viral agglutination Killing of target cell via complement cascade activation
Which antibodies indicate recent infection?
IgM
Which antibodies indicate viral infection?
IgG
What are the main ways by which viruses evade antibodies?
They secrete their antigens to mop up antibodies before they can attach to the virus itself
Exist as many distinct stereotypes with different antigens
What is viral antigenic drift?
When viruses adapt and evolve to evade antibodies
What is viral antigenic shift?
When viruses acquire new antigens via reassortment
What are interferons and when are they produced?
They are small antiviral proteins produced by cells when they detect viral synthesis of foreign molecules eg RNA without a 5’ cap, double stranded RNA, cytoplasmic DNA etc
What interferon receptor do all cells have?
Interferon alpha
What interferon do all cells produce?
Interferon beta
What cells specialise in producing interferon alpha?
Plasmacytoid dendritic cells
How many types of interferon alpha and beta are there?
13/14 interferon alpha types
1 interferon beta type
What are NK cells activated by?
Il-12 and interferon alpha
What do NK cells activate and which molecule do they work with to do this?
They activate macrophages with the help of IL-4
What do NK cells do?
They kill viral infected cells that display fewer than normal MHC molecules by releasing toxic molecules
How do macrophages help fight viral infection?
They filter viruses from blood and inactivate opsonized viruses
How do dendritic cells contribute in the immune response?
They control what type of CD4/CD8 response there will be
Which 2 cell types present antigens to CD4 cells?
Macrophages and dendritic cells
What type of T cell respond to the class 1 MHC complex?
Cytotoxic T cells
What is the common way viruses cause chronic infection?
Disabling T cell responses eg HIV kills CD4 T cells, herpes virus prevents CD8 T cell killing
