Immune responses to virus infection

Question 1

What do infected cells and dendritic cells produce?

Answer 1

Antiviral cytokines and type I interferon a and B

Question 2

What detects viral nucleic acids in plasmacytoid dendritic cells?

Answer 2

TLR7

TLR9

Question 3

What do interferons a and B do?

Answer 3

Inhibit viral replication by inducing dsRNA protein kinase (PKR)and oligoadenylate synthetase

Question 4

What does PKR do?

Answer 4

Inactivation eIF2a so inhibition of protein synthesis

Question 5

What does oligoadenylate do?

Answer 5

Activates RNase L for the degradation of viral RNA so it is difficult for the virus to replicate and produce progeny

Question 6

What are natural killer cells?

Answer 6

Lymphocytes which bind tumour and virus infected cells and kill them by insertion of granules containing perforin.
Circulate in the blood
Activated by interferon a/B

Question 7

What do NTK cells detect?

Answer 7

Generic stressed ligands on cells

Question 8

What recognises the ligands for NK cells

Answer 8

NKG2D NK-activating receptor

Question 9

What are the ligands which induce NK cells?

Answer 9

UK16 binding proteins (ULBP1-6 and MHC class I-related chain A)

Question 10

How do NK cells bind to the target cell?

Answer 10

Lytic immunological synapses

Question 11

What does granzyme B target?

Answer 11

Pro-caspase 3

Question 12

How do mature dendritic cells present antigens to T-cells?

Answer 12

On MHC molecules

Question 13

What do B lymphocytes need to promote proliferation

Answer 13

help from antigen specific CD4+ T lymphocytes

Question 14

what do antibodies do viruses

Answer 14

Prevent viruses binding to the receptors on host cells

Question 15

What is opsinisation?

Answer 15

Fc receptors bind to Fc region of antibody-antigen complexes

Phagocytosis of immunoglobin-bound virus can lead to destruction of the virus

Question 16

how does uptake of immunoglobin-bound virus lead to destruction of the virus?

Answer 16

TRIM21 dependent ubiquitination and proteosomal dependent degradation)

Question 17

What pathways does TRIM21 dependant ubiquitination result in?

Answer 17

Activation of NF-kB, AP-1 and IRF pathways

Question 18

give 4 ways viruses can evade the immune response

Answer 18

1. Interference with IFN a/B
2. Inhibition of NK cell recognition
3. Inhibition of CTL recognition of virally infected cells
4. Inhibition of complement activation

Question 19

Give three examples of inhibition of the interferon a/B response

Answer 19

1. Vaccinia expresses a secreted soluble IFNa receptor
2. Lassa virus nucleoprotein degrades free dsRNAs
3. Adenovirus E1A inhibits IFN transcription.

Question 20

Give 2 examples of inhibition of NK cell recognition

Answer 20

1. HCMV UL16 blocks cell surface expression of NK cell ligands, retaining the proteins in the cell
2. KSHV’s K5 downregulates cell surface expression of MICA and MICB