Latent and Persistent Infections

Question 1

Describe an acute virus infection

Answer 1

rapid onset
brief duration of symptoms
either host or virus is eliminated
active virus replication and immune response then immune memory
too much immune response causes tissue damage

Question 2

Similarities between acute and chronic virus infection

Answer 2

initial steps of infection–virus infects, replicates, and host responds with an immune response

Question 3

How is chronic virus infection different from acute?

Answer 3

virus not eliminated (months, or entire life)
immune response will continue to be stimulated
immune response controlled so that it isn’t too robust
but increased overall systemic levels of inflammation

2 types: latent, persistent

Question 4

Latent virus infection

Answer 4

minimal expression of viral genes
no lytic replication
no virion production

Question 5

What is the prototypical latent virus infection?

Answer 5

herpesvirus

Question 6

Advantages of latent virus infection for the virus

Answer 6

invisible to immune system

cannot be eliminated b/c virus uses host cell machinery to maintain genome

Question 7

disadvantages of latent virus infection for the virus

Answer 7

limited spread to a naive host (no virion production)

death of the infected cell is the end for the virus

Question 8

How do latent viruses overcome its challenges?

Answer 8

limited transmission to naive host–by reactivation to lytic
death of infected cell results in death of virus–by infecting long lived cells

Question 9

What kind of lifestyle does Hepatitis C virus have?

Answer 9

lytic only, chronic persistent

Question 10

In what kind of infections does T cell exhaustion occur?

Answer 10

T cell exhaustion: upregulation of inhibitory receptors that weakens signaling downstream of TCR, leads to loss of antiviral fxns and T cell death

answer: chronic persistent virus infection

Question 11

Pathogenesis of chronic latent infection

Answer 11

very little if any disease

Question 12

Overcoming pathogenesis for latent infection

Answer 12

induce virus reactivation, bu tricky b/c reactivates only small portion of the latently infected cells

vaccine development difficult

can help susceptible hosts by giving antivirals targeting lytic viral replication since this is what produces pathogenesis

Question 13

pathogenesis of chronic virus infec

Answer 13

virus replication causes tissue and cell damage
tissue damage caused by immune response
chronic inflammation can lead to cancer

Question 14

overcoming pathogenesis of persistent infection

Answer 14

therapies target BOTH viral and host processes

viral: target viral replication
host: mild immunosuppresive therapy