Viruses 4 - Classification

Question 1

What type of infection is caused by a virus that is rapid and self-limiting?

Answer 1

Infection cleared by the immune system, leading to recovery

Examples include Influenza Virus and Rotavirus.

Question 2

What is the carrier status duration for FMDV in cattle?

Answer 2

Virus can persist for up to 24 months in the animal after symptoms cleared

For sheep and goats, the duration is 5-12 months; for African buffalo, it can be up to 5 years.

Question 3

What is a characteristic of chronic infections?

Answer 3

Virus persists at very low levels in immune privileged sites

Examples include FeLV and Jaagsiekte ‘chase disease’.

Question 4

What does a latent infection involve?

Answer 4

Virus persists at very low levels and replicates in immune privileged sites

Limited recognition by the immune system of infected cells.

Question 5

What is the potential for a latent infection?

Answer 5

Potential to reactivate usually due to immunosuppression or external stimuli

Example includes Herpesviridae.

Question 6

What is a chronic infection characterized by?

Answer 6

Slow, continuous growth of the virus

Example includes Jaagsiekte ‘chase disease’ (Ovine pulmonary adenocarcinoma).

Question 7

What is the taxonomic classification of viruses based on?

Answer 7

Replication characteristics

This follows the same classification system as all organisms (KPCOFGS).

Question 8

True or False: Chronic infections tend to kill the host.

Answer 8

False

Chronic infections do not tend to kill the host.

Question 9

Fill in the blank: The virus can persist for _______ months in sheep and goats after symptoms clear.

Answer 9

5-12

Question 10

What is a key feature of viruses in latent infection?

Answer 10

No or few viral proteins expressed

This limits the immune system’s recognition of infected cells.