Evolution and emergence of new viruses

Question 1

What is zoonosis?

Answer 1

When a virus emerges from animals (e.g. ebola)

Question 2

How do new viruses emerge?

Answer 2

• Zoonosis
• Genetic variation
• Increased exposure - travel or world population
• Increased exposure - spread of vector
• New discoveries

Question 3

TRUE OR FALSE:

Horses and humas are dead end hosts for West Nile Virus

Answer 3

TRUE

Horses and humans cannot pass on the disease to another type of organism

Question 4

Name some examples of arboviruses

Answer 4

• Yellow fever
• Dengue
• West Nile
• Zika
• Chikingunya

Question 5

Some “new” viruses can be those that are only recently discovered or detected. Name some examples of these “new” viruses.

Answer 5

• Hep C
• Human papillomaviruses 16 and 18 (cause of cervical cancer)
• HHV8 (cause of Kaposi’s sarcoma)
  
  • notice during AIDS pandemic
• Merkel cell polyoma virus (identified in tumours as non-human sequence)

Question 6

Where did HIV emerge from?

Answer 6

Primates

Question 7

Where did SARS (Severe Acute Respiratory Syndrome) coronavirus emerge from?

Answer 7

Bats via propagation in the intermediate animal = civets

Question 8

Where did MERS emerge from?

Answer 8

Closely related to HKU4 and HKU5 = two bat coronaviruses

Current “reservoir” for human infection are in camels

Question 9

What is antigenic drift?

Answer 9

Re-emergence of the same strain of virus

Question 10

How does genetic reassortment lead to antigenic shift?

Answer 10

• Genetic reassortment = swapping of genetic information
• Genes from human virus and avian virus (viruses adapted to birds) combine
  
  • Genes from avian virus give it new antigenicity
  • Leads to a pandemic

Question 11

What might be the next pandemic?

Answer 11

• MERS
• H7N9

Question 12

TRUE OR FALSE:

We are not prepared for the possibility of a MERS pandemic

Answer 12

TRUE

There are diverse clinical signs, no vaccine and no antiviral