Viral Pathogenesis (complete)

Question 1

Describe the effects of tissue tropism on the nature of viral disease

Answer 1

Tropism = Likelihood to infect certain tissues, not others

Determined by a combo of factors:

1) access to tissue in which it can replicate (right tissue???)
2) receptors required for virus binding and entry (right receptors??)
3) a relative failure of host defenses (how easy are they gonna make it for this virus??)

Question 2

Describe the effects of virulence on the nature of viral disease

Answer 2

Four types of virulence genes:

1) Affect ability of virus to replicate
2) Modify host defense mechanisms
3) Facilitate virus spread in and among hosts
4) Directly toxic to host cells

Question 3

Describe the effects of host responses on the nature of viral disease

Answer 3

Factors that affect viral disease:

1) Right receptor
2) Cell type
3) Age
4) Genetic background
5) H/o exposure
6) Immune status

Question 4

Describe the incubation period of acute local disease

Answer 4

Short (1-2 days)

Question 5

Describe virus shedding and transmission in acute local disease

Answer 5

Infection of epithelial cells ONLY

• Infects on the luminal side
• Replicates in epithelial cells
• Sheds back into lumen
• Therefore => no access to blood circulation (NOT SYSTEMIC)

Question 6

Describe host responses in acute local disease

Answer 6

Induces secretory IgA (prevents you from being infected by that exact virus again)

Question 7

Describe the likelihood of reinfection in acute local disease

Answer 7

Common

B/c there are soooo many serotypes (like the common cold)

Question 8

Describe the incubation period of acute systemic disease

Answer 8

10-21 days

Question 9

Describe virus shedding and transmission in acute systemic disease

Answer 9

Two rounds of replication!!

• Primary replication: epithelium => virus in blood
• Secondary rep: Spleen, lung, liver

Question 10

Describe host responses in acute systemic disease

Answer 10

• IgG and secIgA released

- Lifelong immunity to virus

Question 11

Describe the likelihood of reinfection in acute systemic disease

Answer 11

Unlikely

Question 12

What is the difference between persistent and latent infection?

Answer 12

P: ongoing virus production

L: true latent/dormant state — virus is NOT replicating

Question 13

What are different types of viral diseases?

Answer 13

1) Measules
2) Orthopox virus (smallpox)
3) Viral gastroenteritis
4) Rubella
5) Hep B, C
6) HSV
7) HPV
8) Parvovirus
9) Retroviruses