Host response to infectious disease

Question 1

Which PRR recognise viruses?

Answer 1

RIG-I, MDA5, TLR3, TLR7, TLR8, PKR

Question 2

Which cytokines are activated upon viral infection?

Answer 2

IFN-alpha and IFN-beta. IFN-beta is much more effective

Question 3

What is the function of paracrine IFN-beta?

Answer 3

induces anti-viral state, where it usually blocks virus entry

Question 4

What is the function of autocrine IFN-beta?

Answer 4

primes infected cells for programmed cell death & induces intracellular changes aimed at blocking virus replication

Question 5

What do virus-infected cells secrete and which cells are recruited?

Answer 5

secrete cytokines & chemokines. recruit macrophages, neutrophils, NK cells, dendritic cells (arrive 1-3 days after infection) and CD4, CD8 T cells and B cells (recruited by innate cells, begins 5 days after primary infection, 3-4 for secondary infection)

Question 6

What is the function of macrophages in a viral infection?

Answer 6

• secretes IL-6, IL-1beta-TNF-alpha
• present antigen to CD8+ T cells
• eat dead/dying cells
• initiate tissue repair
• collagen synthesis

Question 7

What is the function of neutrophils in a viral infection?

Answer 7

• secrete INF-alpha, IL-8, IFN-gamma, GM-CSF
• MAY also present Ag to CD4+ T cells on MHC II
• degranulate releasing reactive oxygen species & metabolic enzymes
• clear dead/dying cells
• execute tissue repair (the best)

Question 8

What is the function of dendritic cells in a viral infection?

Answer 8

• eat dead/dying cells
• process & present viral Ag on MHC II
• cross-present exogenous Ah on MHC I
• migrates to LN to present to CD4+ and/orCD8+ T cells
• provides survival signal & induces CTL proliferation

Question 9

What is the function of NK cells in a viral infection?

Answer 9

• produce IFN-gamma to support CTL response and shape T cell differentiation into Th1
• directly kill virus-infected cell via release of granules & death receptor