INFLUENZA

Question 1

cause

Answer 1

• influenza A

Question 2

structure of virus (4)

Answer 2

• genetic material = RNA
• 8 single strands rather than 1
• virion surrounded by phospholipid envelope from host’s cell membrane
• envelope contains two types of antigens, proteins acting as spikes on the surface

Question 3

types of antigens on influenza (2)

Answer 3

• (H) haemagglutinin = used in entering host cell

- (N) neuraminidase = used in leaving host cell

Question 4

what makes new strains of flu successful? (2)

Answer 4

• new antigens/arrangement of antigens on virus so immune system cannot protect against
• causes pandemics (i.e spanish influenza)

Question 5

pandemic

Answer 5

epidemic over a wide area, crossing international boundaries, with a huge amount effected

Question 6

transmission (4)

Answer 6

• infect many species hence bird/swine flu
• inhaled in droplets from coughs/sneezes/ aerosol transmission
• mucus protects virus
• survives best in dry air and low UV, i.e winter hence seasonal flu

Question 7

prevention (4)

Answer 7

• regular handwashing
• using and discarding tissues
• vaccines sometimes effective, new one needed annually
• quarantine

Question 8

antigenic types in influenza (2)

Answer 8

• antigenic drift

- antigenic shift

Question 9

antigenic drift (4)

Answer 9

• no RNA proof-reading enzymes
• so each replication produces a new mutation
• causes a gradual change in surface proteins
• why a new vaccine is needed yearly

Question 10

antigenic shift (3)

Answer 10

• flu strains can recombine to make new antigen combinations
• can cause epidemics
• pigs/birds can act as reservoirs as the virus mutates to infect humans

Question 11

epidemic

Answer 11

rapid spread of disease to a large number of people in a short time