Viral Evasion

Question 1

Antiviral action of IFN:

Answer 1

IFN-gamma produced by immune response
IFN-gamma binds to virus infected cell, as well as binding to and signalling to neighboring uninfected cells
IFN-alpha/beta are produced
IFNs induces an “antiviral state” in cells, that limits virus replication

Question 2

The immediate response to viral infection relies on:

Answer 2

PRRs recognising PAMPs (e.g. viral proteins)

Engagement of these receptors then initiates intracellular signaling cascades which ultimately cause the activation of transcription factors and the expression of type I interferons and pro-inflammatory cytokines.

This innate response establishes an anti-viral state in the infected cell and its neighbours and alerts immune cells to the danger. In order to establish a productive infection, viruses need to overcome this initial anti-viral response.

Evasion of innate immune defenses is achieved by means of viral proteins that inhibit the signaling cascades emanating from the PRRs

Question 3

IFN induces a pro-viral state in cells

TRUE OR FALSE

Answer 3

FALSE

IFN induces an anti-viral state in cells

Question 4

Virus inhibition of the interferon response:

Answer 4

By generally interfering with host cell gene expression.
By blocking IFN production.
By inhibiting IFN signaling.
By inhibiting the action of IFN-induced enzyme with anti-viral activity.
By having a replication strategy which is insensitive to the action of IFN.

Question 5

Viral anticytokine strategies:

Answer 5

Homologues of cellular cytokines that influence the development of the immune response.
Homologues of cellular cytokine receptors, e.g. TNF, IFN, IL-1, IL-18
Binds chemokines (bind CKs or CK receptors)
Inhibit intracellular signalling pathway, e.g. induction of chemokines/cytokines (via NF-kB activation) or IFN response.
Block cytokine secretion