Lecture 12

Question 1

OAS and RNase L

Answer 1

• OAS is 2’-5’-oligoadenylate synthetase that,
  upon activation by dsRNA, catalyzes the
  synthesis of oligomers of adenylic acid.
• These unusual nucleotide oligomers (oligo-
  (A)) activate RNase L, another IFN stimulated
  gene, which then begins to degrade viral and
  cellular mRNAs
• The result of all this is an inhibition of viral
  and cellular protein synthesis and induction of
  apoptosis.

Question 2

Virus Mediated Inhibition of OAS/RNase L

Answer 2

• HIV infection induces the production of an
  RNase L inhibitor.
• Reovirus σ3 protein, Rotavirus nsP3
  protein and Influenza A NS1 protein bind
  dsRNA and inhibit PKR and OAS

Question 3

MxA Proteins

Question 4

Virus Mediated Inhibition of Mx Proteins

Answer 4

• Viruses can evade the antiviral effects of
  Mx proteins through adaptive mutations in
  their nucleoprotein/capsid protein, which is
  a key determinant of Mx sensitivity. (e.g.
  influenza A viruses)
• These mutations can allow viruses to
  overcome the ability of Mx proteins to
  restrict viral replication.