Virology 2

Question 1

Distinguish enveloped viruses and non-enveloped viruses in terms of sensitivities.

Answer 1

Enveloped viruses are sensitive to dessication, extreme pH and require direct contact via blood.

Question 2

What happens to a cell in a lytic infection vs a non-lytic infection?

Answer 2

Lytic infections lead to death. Non-lytic infected cells produce virus by budding.

Question 3

What is the host’s main defense against viral infections?

Answer 3

Inferferons alpha and beta. Binding of interferons to their receptors causes the cell to go into an antiviral state. DsRNA induces IFN synthesis.

Question 4

Discuss the MOA for IFN-induced proteins.

Answer 4

A dsRNA protein kinase, Pkr, is made in its inactive form in response to IFN treatment of uninfected cell. dsRNA activates Pkr which phosphorylates elF2a which inhibits translaion of both viral and cellular proteins.

Question 5

What is the role of oligoA synthase?

Answer 5

Activated by dsRNA, makes oligoA which activates RNase L; Degrades viral and cellular RNAs

Question 6

What is the role of humoral immunity in viral infections?

Answer 6

Make neutralizing antibodies the prevent virus from entering a host cell.

Question 7

Discuss cellular immunity in viral diseases

Answer 7

Viral proteins are bound to MHC 1 and presented. Recognized and lysed by CD8s; Requires two signals

Question 8

How can a virus avoid the immune system?

Answer 8

1. Antigenic variation
2. Restrict expression of viral gene products.
3. Suppresion of MHC 1 expression
4. Decreased cell adhesion
5. Killing immune cells.

Question 9

Whats the main dis/advantages of Live viral vaccines?

Answer 9

Adv: Stimulates both humoral and cellular immune system; Long term immunity.
Disadv: Can cause disease or revert back to virulence.

Question 10

Discuss Inactivated viral vaccines

Answer 10

Eliminate infectivity without destroying antigenicity. Requires adjuvants and is inefficient at inducing cellular and long-term immunity