Influenza & Ebola

Question 1

Influenza structure

Answer 1

enveloped negative sense ssRNA

Question 2

Influenza entry & transmission

Answer 2

1. droplets enter respiratory tract
2. binds to sialic acid containing receptors (SA alpha 2-6 linkage with galactose)
3. fusion of membranes via acidic conditions
4. virus replicates, causing inflammatory response and therefore symptoms

Question 3

types of Influenza

Answer 3

• type A, B & C
• A & B for humans
• A can infect animal reservoirs

Question 4

hemaglutinin (HA)

Answer 4

assists virus entry into cell by binding to sialic acid linked to galactose receptors

Question 5

neuraminidase (NA)

Answer 5

assists virus exiting the cell by cutting SA from HA receptor

Question 6

M1

Answer 6

structural, rigid matrix that holds virion together

Question 7

M2

Answer 7

ion protein

Question 8

ribonucleoproteins (RNP)

Answer 8

polymerase, RNA, nucleoproteins

Question 9

nuclear export proteins (NEP)

Answer 9

moves products into and out of nucleus

Question 10

non structural protein (NSP 1)

Answer 10

anti-interferon activity

Question 11

current influenza A subtype infecting humans

Answer 11

H1-N3 & H3-N2

Question 12

How do replicated virions become infectious?

Answer 12

trypsin must bind to the hydrophobic fusion peptide of recently cleaved HA

Question 13

Influenza innate immune response (immediate)

Answer 13

• lung surfactant proteins prevent viral binding
• collectins bind to HA & NA to block binding process
• triggers lectin pathway of complement cascade

Question 14

Influenza innate immune response (delayed)

Answer 14

• infected epithelial cells produce type 1 interferons
• PAMP-PRR interactions trigger inflammatory cells
• cytokine release

Question 15

Influenza adaptive immune response

Answer 15

• CD8+ cytotoxic T cells

- antibody to HA & NA

Question 16

antigenic drift

Answer 16

single mutations in viral replication creates new strains within subtypes, mutations must occur in all 5 antigenic sites before antigenic drift occurs and an epidemic breaks

Question 17

Influenza diagnosis - rapid diagnostic test

Answer 17

To determine if type A or type B

• positive for A: C & flu A line
• positive for B: C & flu B line
• positive for A & B: C, flu A & flu B
• just C = negative for influenza

Question 18

Influenza diagnosis - culture & HIA test

Answer 18

To determine which strain/subtype

• allantoic fluid from infected embryonated avian eggs
• reference antisera (from ferrets/rabbits) inhibits agglutination of HA with red blood cell sialic acid

Question 19

Influenza vaccine

Answer 19

inactivated trivalent vaccine: type A H1N1, type A H3N2, type B

Question 20

Influenza treatment

Answer 20

• adamantanes: M2/ion channel blockers, only active for type A
• relenza (zanamivir) & tamiflu: NA inhibitors, active against A & B

Question 21

Ebola structure

Answer 21

negative sense ssRNA

Question 22

Why is ebola so dangerous?

Answer 22

• highly contagious, transmission through any direct contact with bodily fluids
• no vaccines or treatments

Question 23

antigenic shift

Answer 23

introduction of new subtype of influenza, therefore creating a pandemic