Session 10- Influenza and Virology

Question 1

What is flu

Answer 1

An acute viral infection of the respiratory tract

Question 2

Structure of the influenza virus

Answer 2

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

2 surface antigens

• haemagglutinin (H) - 18 types binds to cell of infected person
• Neuraminidase (N) - 11 types - releases the virus from the host cell surface

Question 3

Influenza A

Answer 3

Affects many animals undergoes antigenic drift and is responsible for pandemics

Question 4

Influenza B

Answer 4

Only affects humans and undergoes antigenic drift- mainly affects older adults

Question 5

Influenza c

Answer 5

Affects humans and pigs and undergoes antigenic drift and produces mild disease

Question 6

How are influenza viruses transmitted

Answer 6

Person to person via the respiratory route- coughing, sneezing, inhaling

Question 7

What are the first lines of defence in the innate immun system

Answer 7

1) respiratory epithelial cells are covered by a thick glycocalyx and tracheobronchial mucus that can trap viruses
2) ciliated respiratory epithelial cells continually sweep mucus up from the lower respiratory tract into the upper respiratory tract where it is swallowed
3) immunologic defences include secretatory IgA, natural killer cells and macrophages

Question 8

How do viruses enter cells

Answer 8

They attach to sialic acid residues on host cell glycoproteins or glycolipids then entry via receptor-mediated endocytosis

Question 9

What is attachment and fusion function associated with

Answer 9

Haemagglutinin protein

Question 10

What is the viral release facilitated by

Answer 10

Neuraminidase protein which cleaves the sialic acid residue of the glycoprotein on the cell surface allowing release

Question 11

Symptoms of i influenza

Answer 11

Fever 
Headache \
Sore throat 
Cough
Aches
Pains

Question 12

Incubation time for influenza

Answer 12

5 days

Question 13

Treatment of influenza

Answer 13

Antivirals
Neuraminidase inhibitors
Vaccination of vulnerable groups

Question 14

What is genetic drift

Answer 14

Genome of the virus is constantly changing in small ways- point mutations- and this leads to genetic variation in both the surface antigens H and N

not as bad

Question 15

What is antigenic shift

Answer 15

Major changes in the genes of flu viruses that occur suddenly when two or more different strains combine which results in a new subtype and is the
cause of widespread epidemics/pandemics

This refers to major changes in H and N proteins

VERY BAD