Influenza

Question 1

Influenza virus causes a/n Acute/Persistent/ Latent/Slow Virus Infection

Answer 1

Influenza virus causes an Acute Infection

Question 2

Structure of Influenza Virus:

Answer 2

Segmented genome of negative single strands of RNA
Enveloped virus
Neuraminidase (NA)
Haemagglutinin (HA)

HA is required for entry of virus into cells via binding to cell surface receptor/s.

NA is required for virus exit, and is the target for anti-viral drugs.

2 Other Surface proteins:
Matrix - M1
Ion Channel - M2

Virion Interior Proteins:
PB1, PB2, PA, NP
PB1, PB2, PA: Make up “replicase” RNA-dependent RNA polymerase

Question 3

Influenza Virus Life Cycle:

Answer 3

Virus recognises Sialic Acid (A carbohydrate on the cell surface of nearly all cell types)
Endocytosis of virus
Escapes from endosomes through fusion, releasing virus into cell cytoplasm
Viral protein translocates to nucleus and starts making mRNA which is then translated by cell ribosomes, replicating more virus genomes.
Budding of new viruses through cell membrane.

Question 4

Influenza Virus Replication is prone to mutations

TRUE OR FALSE

Answer 4

TRUE

Allows variations

Question 5

Influenza Virus needs to convert its negative RNA strand to a positive RNA strand.
TRUE OR FALSE

Answer 5

TRUE

Question 6

Virus proteins can steal mRNA caps/polyA tails in order to protect the Viral RNA

Answer 6

TRUE

Prevents recognition of viral RNA as being foreign

Question 7

Replication of viral RNA

Answer 7

Takes host mRNA Cleaves and steals its 5’ end
Uses this 5’ end to copy the negative strand viral RNA into positive strand viral RNA

PB1 holds negative strand
PB2 steals 5’ end

Question 8

HA trimer:

Answer 8

Globular head, binds to cell surface receptor
C-terminus stalk embedded in membrane
Protease cleavage site in stalk region

Question 9

Antigenic shift:

Answer 9

Process by which two or more different strains of a virus combine to form a new subtype having a mixture of the surface antigens of the two or more original strains

Question 10

Influenza vaccine production occurs in eggs

TRUE OR FALSE

Answer 10

TRUE

Question 11

Cleavage of protease cleavage site in stalk region of HA trimer leads to generation of BLANK

Answer 11

Cleavage of protease cleavage site in stalk region of HA trimer leads to generation of fusion peptide.
Fusion peptide inserts itself into cell membrane of endosome, driving fusion.