7. Olds (1st exam - 1)

Question 1

How were wild-type hog cholera virus strains lapinized?

Answer 1

• WT hog cholera virus were inoculated into rabbits multiple times (~200 times?) until the strain mutated and adapted to their new host species.
• Once the mutated strain was injected into the original host species, they were no longer able to cause infection due to a change in receptor specificity.
• Thus, swine are resistant to the lapinized strain of hog cholera virus.

Question 2

Why are naked viruses more stable in the environment than enveloped viruses?

Answer 2

The viral ligands of enveloped viruses are located on their lipid envelopes, which are destroyed much more easily than the protein capsids of naked viruses.

Once the ligands are destroyed, then the virus can no longer infect cells.

Question 3

Give the 5 prerequisites of an ideal diagnostic test.

Answer 3

1. Speed
2. Simplicity
3. Sensitive
4. Specific
5. Low cost

Question 4

Explain how dendritic cells play a role in the immune response.

Answer 4

• Uptake or PHAGOCYTOSIS of Ag➡️DC enlarge and pick up Ag
• Breakdown or PROCESSING of phagocytosed Ag➡️formation of phagolysosome as DC travels inside the afferent lymphatics
• Display or PRESENTATION of processed Ag➡️Ag fragments displayed on the surface of DC may activate specific lymphocytes

Question 5

How do Th1 and Th2 cells activate the adaptive immunity?

Answer 5

• Th1 binds to DC displaying MHC 2 + exogenous Ag➡️activates CTL➡️cell-mediated immunity
• Th2 binds to DC displaying MHC 2 + exogenous Ag➡️activates B cells➡️plasma cells➡️secretion of Abs