Influenza A Essay

Question 1

What is the structure of influenza A

Answer 1

Mainly spherical, enveloped, ssRNA, negative sense

Question 2

What is the size of the influenza A genome

Answer 2

13.5 kilobases

Question 3

What is the role of the glycoprotein haemagglutinin (HA)

Answer 3

Binds sailor acid for viral entry

Agglutinate RBCs

Question 4

What is the role of the glycoprotein neuramimidase (NA)

Answer 4

Creates sialic acid to release

Question 5

What is the role of the matrix protein 2

Answer 5

Forms protein channel that facilitates uncoating and assembly
Stabilises the virus building
Antigenic neutralising
An outer lipid bilayer formed from the lipid bilayer of infected host (supported by the M1 protein which plays a role in virion assembly)

Question 6

Describe the attachment in the influenza virus replication cycle

Answer 6

By binding to HA-sialic acid on host cell. Virus is endocytosed and a vesicle membrane forms. The vesicle is transferred to the endosome.

Question 7

Describe the uncoating in the influenza virus replication cycle

Answer 7

Endosome acidification - M2 increases the H+ concentration leading to uncoating

Question 8

Describe the transcription stage in the influenza virus replication cycle

Answer 8

Nucleocapsid goes to the nucleus and transcribes mRNA and translates this into proteins in the cytoplasm

Question 9

Describe the replication stage of the influenza virus replication cycle

Answer 9

vRNP is converted into cRNP (ribonucleoprotein)

Question 10

Describe assembly in the influenza virus replication cycle

Answer 10

HA/NA is transported to cell surface with M1 and genome segments

Question 11

What is the final stage of the influenza replication cycle?

Answer 11

Virus buds off by NA

Question 12

What is antigenic drift?

Answer 12

Minor changes in the antigenic sites of the HA and NA because of error prone replication and no proofreading. This provides a selective advantage for seasonal flu

Question 13

What is antigenic shift

Answer 13

Major changes due to reassert,ent of genes that occurs when two different influenza viruses infect the same host. This occurs due to segmented genome and wide host ranges. Leads to complete change of HA, NA or both. Only occurs in influenza A. Usually requires non-human intermediate

Question 14

How do adamantanes treat influenza A?

Answer 14

They block viral uncoating

Question 15

What is the incubation period for influenza A

Answer 15

Usually 2 days but can range from 1 to 4 days