Viral Pathogenesis

Question 1

What is tissue tropism?

Answer 1

Tissue specific –> more likely to infect certain tissues and not others

Question 2

What are the factors influencing tissue tropism? (4)

Answer 2

1. Access to tissue for replication
2. Required receptors for binding/entry
3. Expression of host gene for viral production and future infection
4. Activity of host defense

Question 3

Compare the method of viral transmission in local infection and systemic disease

Answer 3

1. Local infection: Shedding from initial infection site

2. Systemic disease: Shedding from multiple, distant sites

Question 4

What factors influence the means of viral transmission?

Answer 4

1. Site of virus replication/release

2. Stability of virus particle

Question 5

Compare the method of viral transmission for enveloped and naked viruses

Answer 5

1. Enveloped virus: fragile and sensitive to environment
   * Close contact transmission
2. Naked virus: sustain environmental stress
   * transmitted via virus-associated object
   * through respiratory or fecal/oral route

Question 6

What are the environmental stresses affecting viral transmission? (3)

Answer 6

1. pH
2. temperature
3. detergent

Question 7

List 4 host factors in susceptibility to viral disease.

Answer 7

1. Appropriate receptors for virus entry
2. Host age
3. Genetic background
4. Immune status

Question 8

Mechanism of immune-mediated viral infection

Answer 8

1. Antibody mediated (immune complex)
2. Cell mediated (rash, fever, malaise)
3. Autoimmune (cross-reactivity)
4. Transient immune modulation (immune suppression)

Question 9

Compare acute local and acute systemic infection

Answer 9

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