Influenza Virus and Vaccines

Question 1

Describe the structure of Orthomyxovirus

Answer 1

negative sense, segmented RNA, helical, Enveloped

Question 2

What are the types of Influenza?

Answer 2

Influenza A
Influenza B

Question 3

Describe Influenza A

Answer 3

-Infects Humans, swine, and avians
-Is capable of antigenic drift and shift
-Combines hemagglutinin 1,2, or 3 with neuraminidase 1 or 2.
-Is the cause of most epidemics and all pandemics

Question 4

Describe Influenza B

Answer 4

-Infects humans
-Genetic drift is the genetic change that is most problematics
-Can result in reinfection and changing the vaccine, rare epidemics, and no pandemics

Question 5

What does Antigenic Drift result in?

Answer 5

-Small changes in the virus
-The most critical mutations are in the hemagglutinin (HA) envelope protein
-Mutations in HA have the potential to allow the virus to escape neutralizing antibodies
-*Antigenic drift in HA will enable the virus to reinfect people and is the reason to change the flu vaccine

Question 6

What is Antigenic shift?

Answer 6

-Large changes
-Is the swapping of viral RNA segments between human and avian, or human and swine, or all three viruses
-This mixing can sometimes lead to a vastly new virus that can cause a pandemic

Question 7

How is Influenza spread?

Answer 7

Person to person via respiratory droplets and fomites

Question 8

How is influenza killed?

Answer 8

Influenza is an enveloped virus and is killed with detergents, heat, acid, and drying

Question 9

Most of the deaths caused by influenza are by people of what age group?

Answer 9

65+

-A large number of people are infected each year with thousands of hospitalizations. Most hospitalizations occur in people with underlying health conditions, but previously healthy adults and children are hospitalized and some die yearly

Question 10

A ______ strain of influenza will become the new sessional influenza until supplanted by a new pandemic strain

Answer 10

pandemic

Question 11

What type of infection is influenza and what it its incubation time?

Answer 11

Local infection; short incubation time

Question 12

How long to influenza symptoms last?

Answer 12

Symptoms last 2-3 days and can be as long as 5. Most recover, but some lack strength and energy for several weeks; a cough can linger

Question 13

When do adults shed the virus? Children?

Answer 13

-Adults shed the virus one day before symptoms to 5-7 days after
-Children can shed up to 10 days after symptoms

Question 14

What are about 1/3 of influenza deaths due to?

Answer 14

-Secondary bacterial pneumonia (Pneumonia caused by influenza is rarer but is generally worse and has a high fatality rate.)
-Other causes are due to underlying health problems such as heart disease or pulmonary disease

Question 15

The viral Hemagglutinin binds to _______

Answer 15

sialic acid

Question 16

The _____ linkage is the type human influenza virus bind.

Answer 16

alpha2-6

-It is present in the upper respiratory tract at high levels and only in the lower respiratory tract at low levels

Question 17

Bacterial pneumonia is most prevalent in people with underlying lung problems, but even the healthy can get secondary bacterial infections. List the ways how.

Answer 17

1) Killing air epithelial cells make it easier for bacteria to bind in the airway
2) Influenza can kill alveolar macrophages that help prevent bacterial infection
3) Airway edema and dead cells create a nutrient-rich environment for bacterial growth
4) The viral neuraminidase inactivates some innate antimicrobials that might help kill bacteria and exposes bacterial attachment sites

Question 18

___________ is a detergent disrupted inactivated virus. Just the HA and NA are isolated and put in the vaccine

Answer 18

Inactivated Influenza Vaccine (IIV)

Question 19

_________ contains a cold-adapted influenza virus containing the HA and NA in the inactivated vaccine

Answer 19

Live attenuated influenza vaccine (LAIV)

Question 20

________ contains an entirely recombinant HA protein grown in cell culture

Answer 20

Subunit vaccine (RIV)

Question 21

All of the influenza vaccines are ______

Answer 21

quadrivalent

Question 22

What does the quadrivalent vaccine contain?

Answer 22

Two strains of influenza A and two strains of influenza B

Question 23

How do they pick the vaccine strain for influenza?

Answer 23

It takes time to make the vaccine. This means the vaccine strains must be picked well before the flu
season. They do this by seeing what strains of influenza are prevalent in other parts of the world. These viruses will go into our seasonal influenza vaccine.

Question 24

Protection from influenza infection is achieved ________ after vaccination

Answer 24

2 weeks

Question 25

List the neuraminidase inhibitors

Answer 25

Zanamivir and Oseltamivir

Question 26

What do Zanamivir and Oseltamivir do?

Answer 26

-They prevent the budding and release of the virus.
-It must be used within 2-3 days of infection to have a maximal effect

Question 27

What is the new drug used to treat influenza?

Answer 27

Baloxzvir

Question 28

What is the function of Baloxzvir?

Answer 28

-It is a cap-dependent endonuclease inhibitor
-It block the ability of the virus to ‘snatch caps’ and transcribe viral mRNA
-It seems to be as effective as neuraminidase inhibitors
-It should be used within 2-3 days of infection for effectiveness

Question 29

Describe the 1918 flu epidemic

Answer 29

1) Infected 1/3 to 1/2 of the world’s population
2) Fatality rate >2.5%
3) It had a W-shaped mortality curve, meaning more deaths in the 18-40 year age than normal for influenza

Question 30

Avian strains recognize _______ linkages, which are present more in the lower respiratory tract

Answer 30

alpha 2,3 Sialic acid linkages

-This makes for a more severe LRT infection but also less spread from person to person

Question 31

Human strains recognize _________ linkages present at higher levels in the Upper Respiratory Tract

Answer 31

alpha 2,6 Sialic acid linkages

-This alpha 2,6 Sialic acid usage means there is less chance of LRT infection but much more efficient person-to-person spread

Question 32

What would happen if you have a strain like the 1918 that can efficiently infect both the upper and lower respiratory tracts?

Answer 32

There can be severe LRT infections and efficient person-to-erson spread

Question 33

A _______ is present in avian flu and the 1918 influenza but not in human influenza

Answer 33

virulence factor

Question 34

Another necessity in a pandemic strain is _________ in the population to the new influenza virus

Answer 34

little immunity

Question 35

What is the “Bird” Flue designated as? What is this based on?

Answer 35

-Designated HPAI or LPAI-High Pathogenic or Low Pathogenic Avian Influenza
-Based on the ability of the virus to kill chickens, not humans

Question 36

What are the two main avian influenzas that have crossed over to infect humans?

Answer 36

H5N1 and H7N9

Question 37

What is H5N1considered?

Answer 37

HPAI and can cause devastation in the poultry industry

Question 38

What are the two strains of H7N9

Answer 38

LPAI and HPI

Question 39

Is either H5N1 or H7N9 spread person-to-person?

Answer 39

Neither virus is efficiently spread from person-to-person