Lecture 17- Influenza

Question 1

Viral structure?

Answer 1

Delivery system with internal payload that contains genome and enzymes necessarily for first few steps of viral replication

Question 2

What is flu?

Answer 2

Acute viral infection of respiratory tract including throat, mouth, nose, bronchial tubes and lungs

Question 3

What type of virus is influenza?

Answer 3

Orthomyxovirus which is a spherical, enveloped virus containing a segmented, negative strand RNA genome

Question 4

What is significant about influenza RNA polymerase?

Answer 4

Have high error rates leading to antigenic drift

Question 5

What are the two significant surface antigens of influenza?

Answer 5

Haemagglutinin which helps attach to cell and neuraminidase which helps replicated viruses leave cell

Question 6

Why is influenza A most significant

Answer 6

Seen in many species which means it can cause huge pandemics. Also unlike influenza B it can undergo antigenic shift as well as drift and can cause pandemics

Question 7

What causes RNA replication in viruses?

Answer 7

RNA- dependent RNA polymerase

Question 8

How is RNA replicated in viruses?

Answer 8

Negative single strand RNA converted to positive strand and mRNA which goes to form protein and negative single stranded RNA to make new viruses

Question 9

How I’d flu spread?

Answer 9

Small particles aerosols stay in air

Larger droplets coughed onto someone within 3m

Cough onto surface

Question 10

Barriers to virus?

Answer 10

Ciliaa
Mucus
Immunogenicity defence like natural killer cells and macrophages

Question 11

Influenza symptoms?

Answer 11

Headache, fever , dry cough, sore throat, nausea, diarrhoea, fatigue etc but up to 75% have no symptoms

Question 12

Influence incubation?

Answer 12

1-5 days and with no symptoms can still infect others

Question 13

Risk people with influenza

Answer 13

Children under 6 months 
Over 65
Immunocompromised 
Pregnant women 
High BMI over 40

Question 14

How to diagnose influenza?

Answer 14

Range of diagnostic tests but usually use clinical assessment and history. Use tests if admitted to hospital etc

Question 15

Influenza treatments.

Answer 15

Antivirals not used m,ugh due to resistance

Neuramidase inhibitirs like tamiflu

Prevention through vaccination

Question 16

Influenza vaccinations?

Answer 16

I activated vaccine and attenuated vaccin. Attenuated usually given to children.

I activated can be quad rivals to or trivalent depending on how many strains it works against

Question 17

What is antigenic drift?

Answer 17

Small mutations in haemagluttinin and neuraminidase that occur gradually over time due to error prone rna polymerase

Question 18

Antigenic shift?

Answer 18

Only influenza type A and only occurs every 10-20 years and can cause pandemics.

Two or more different strains combine to give a different sub type of flu. Occurs when influenza viruses from several different species occur in the same host

Question 19

How does reassortement occur in antigenic shift?

Answer 19

Environments where pigs, birds humans etc live close together a pig can be simultaneously infected with multiple influenza subtypes and a new subtype can arise which can spread to humans and birds etc

Question 20

How does flu kill?

Answer 20

Causes immune response that triggers antibodies and immune cells which move to infection site and release cytokines leading to inflammation.

Immune system can overreact and damage lung tissue and cause secondary opportunistic inf3ction fr9mvorganisms like streptococcus or staphylococcus

Question 21

Who should get flu vaccine?

Answer 21

The old, the young
Health care workers
Chronic medical conditions
Pregnant women

Question 22

Effects of flu with pregnancy?

Answer 22

Lower birth rate
Increased maternal complications
Increased risk of prematurity
Increased risk of perinatal mortality