Influenza (OrthoMyxoViridae)

Question 1

Properties

Answer 1

ssRNA virus.
Enveloped.
Negative-sense RNA.
Must bring own RNA polymerase to make a positive sense.
Replicates in Nucleus (Big Exception)
8 segments, 8 places where mutation can be formed.

Question 2

Diseases

Answer 2

Strain ABC - MOST COMMON CAUSE OF FLU

Question 3

Mutations

Answer 3

Antigenic Drift: Point mutation in Viral RNA leading to changes in NA, HA.
.Epidemics
Swine-Flu H1N1

Antigenic Shift:
Assortment of genes with differetn species.
Pandemics

Question 4

Influenze A

Answer 4

Epidemic and Pandemic

Question 5

Influenza b

Answer 5

Endemics

Question 6

Pathogenesis

Answer 6

1. HA Binds to Sialyl receptors on epithelium and RBCs.
2. Endocytosed by cells.
3. M2 proteins causes H+ influx from Lysosomes. (Amantadine, Rimantidine - works only on H.influenza A)
4. Uncoating.
5. Genome enters nucleus, RNA polymerase uses CAP from host mRNA to make it’s mRNA which is +ve sense which makes capsid and glycoproteins as well as RNA polymerase. This polymerase makes -sense mRNA.
6. Packaging happens at Golgi. Exit but still attached via HA.
7. Neuraminidases cleave HA. Releasing our virions. (Oseltamivir, Zenamivir acts here).

Question 7

Transmission

Answer 7

Respiratory Droplets

Question 8

Vaccine

Answer 8

Live Vaccine - IM
Killed vaccine - intranasal

Question 9

Complications

Answer 9

1. SA pnemonia after H. viral.
2. Reyes Syndrome if Aspirin is used.
3. GBS

Question 10

Why Aspirin ain’t used in viral infections?

Answer 10

Aspirin: Hepatic megaly, fever and rash, Encephalitis [Reiter]
.
.uncoupling at mt. level.