59- Orthomyxoviruses

Question 1

What’s the structure of the influenza viruses?

Answer 1

• Enveloped, RNA. It has two main proteins in the outer shell, Hemagglutinin (HA), and Neuraminidase (NA). HA allows entry into the cell, binding to sialic acid and providing attachment. NA cleaves sialic acid and breaks through the glycoprotein matrix.

Question 2

What is the difference between influenza A and B?

Answer 2

• Influenza A is more prevalent with animals, particularly birds (Avian bird flu, swine flu), and can undergo major and minor antigenic shifts (changes in outer protein coating) but influenza B is almost only in humans and undergoes less change in antigenic drift.

Question 3

Recognize the nomenclature (classification) of influenza viruses, for example A/Bankok/1/79/ (H3N2).

Answer 3

1. Type, 2. Place of original isolation, 3. Date of original isolation, 4. Antigen (different mutations end up with different variations of HA and NA, leading to designation H1/N1)

Question 4

What is antigenic drift?

Answer 4

• Antigenic Drift is minor changes from mutation of HA/NA genes mainly, and happens 2-3 years, and cause local outbreaks but not pandemic ones. Antigenic shift is found only in influenza A, and this is the dangerous type that causes potential pandemics.

Question 5

What is antigenic shift?

Answer 5

. Antigenic shift comes with reassortment of genomes, including animal ones, leading to the avian flu/swine flu deadly variants.

Question 6

How is influenze transmitted?

Answer 6

• Airborne droplets and countertops.

Question 7

What are the clinical syndromes of the influenza infections?

Answer 7

• People begin with a flu syndrome for the first 1-4 days, mainly malaise, headache. Then fever, chills, nonproductive cough. Respiratory tract infections can follow, and complications as a result of influenza can occur. Complications include primary viral pneumonia and the secondary bacterial pneumonia that comes after influenza has weakened the immune system.

Question 8

Amantadine/Rimantadine- mechanism of action

Answer 8

Stop uncoating by blocking M2 ion channel (proton channel)

Question 9

Amantadine/Rimantadine- viruses inhibited

Answer 9

Only A

Question 10

Zanamivir/Oseltamivir- mechanism of action

Answer 10

Analogues of sialic acid, block neuraminidase, and slow down the infection process

Question 11

Zanamivir/Oseltamivir- viruses inhibited

Answer 11

A and B