Avian Influenza Virus

Question 1

What family does influenza belong to?

Answer 1

Orthomyxoviridae family

Question 2

What is influenza A?

Answer 2

Causes influenza infections in both animals and people
Usually seasonal
has 8 segments with two strains

Question 3

What is influenza B?

Answer 3

Has a more limited host range- only affects humans and seals
Causes seasonal influenza in humans

Question 4

What is influenza C?

Answer 4

• Limited host range- only affects humans and pigs
• Rare infections in people- only 7 segments

Question 5

What are the two major envelope proteins in the influenza A virus?

Answer 5

• Haemagglutinin, HA, H
• Neuraminidase, NA, N

Question 6

What is influenza A subtyping based on?

Answer 6

the antigenicity

Question 7

How many genome segments are found inside of influenza?

Answer 7

8

Question 8

What is the main innate immune response of avian influenza?

Answer 8

It has a specific protein NS1
that blocks the production of interferon gamma

Question 9

How many subtypes of HA are there?

Answer 9

18

Question 10

How many subtypes of NA are there?

Answer 10

11

Question 11

What is thought to be the main reservoir of all influenza

Answer 11

aquatic waterfowl

Question 12

What are the main symptoms of LPAI ( low pathogenicity avian influenza)

Answer 12

• ruffled feathers
• loss in egg production
• reduced weight gain

Question 13

Name five symptoms of high pathogencity avian infleunza

Answer 13

1. failure to eat
2. fever or noticeable increase in body temp
3. mucus discharge
4. diarrhoea
5. neurological signs

Question 14

Name four ways the avian influenza virus can be transmissed

Answer 14

1. Direct-Direct contact
2. contaminated faeces and bodily fluids
3. contaminated feed and water
4. vehicles, clothing and footwear

Question 15

What samples of avian influenza may DEFRA take for testing?

Answer 15

• swabs (oro-pharyngeal)
• tissue samples
• blood samples
• carcass depending on the species

Question 16

What control strategies may DEFRA put in place for avian influenza?

Answer 16

• Cull birds on infected premises
• may put a place in a restricted zone
• no movement of poultry, eggs etc
• no gatherings of poultry

Question 17

Name four ways to reduce human to animal transmission

Answer 17

1. Surveillance
2. Reduce the exposure
3. Seek medical assistance
4. Education of the public

Question 18

What is the inactivated vaccine given to humans?

Answer 18

• Strain that grows well in eggs
• typically given by intramuscular innoculation

Question 19

What is the live attenuated vaccine given to humans?

Answer 19

• addition of mutations to make the vaccine sensitive
• adminsitered by an intranasal spray twice a year in the nasal passages

Question 20

What occurs to the haemagglutinin when the virus enters an endosome?

Answer 20

• HA acidification
• Causes the core to loosen
• low pH then causes haemagglutin to fuse with the endosome and uncoat

Question 21

What is the innate anti-viral response?

Answer 21

• Virus encodes a non-structural protein which antagonises the induction of type I IFN
• Prevents RIG-I activation (receptor for inteferon I)
• Prevents RIG-I signalling

Question 22

What is the adaptive anti-viral response?

Answer 22

• Dendritic cells present the antigen to T lymphocytes in the lymph node
• T cells leave the lymph node, circulate in the blood and hone to the infection site
• IFN activates macrophages and other cells at the site of infection
• CD8 kills infected cells to stop the spread of infection

Question 23

Name one example of low pathogenicity avian influenza

Answer 23

• H9N2
• Prevalent in Asia and the Middle East
• still causes production losses and is economically important

Question 24

What two LPAI can mutate to become HPAI?

Answer 24

• H5
• H7