Mi - Pandemic Flu / COVID

Question 1

3 ingredients for a pandemic

Answer 1

Novel antigenicity
Replicate efficiently in human cells
Transmit efficiently between humans

Question 2

Where is the influenza reservoir?

Answer 2

Wild aquatic birds

Question 3

Describe influenza genome

Answer 3

8 RNA sections

Question 4

How can avian influenza adapt to use human cell proteins?

Answer 4

Change in haemaglutanin that binds to human cells, so that avian influenza can use human polymerase
Human ANP23 is short, while avian ANP23 is long
Needs PB2 627k mutation so avian can use shorter human ANP23

Question 5

What process allows avian influenza to replicate in humans?

Answer 5

Reassortment / antigenic shift

Question 6

How does reassortment occur?

Answer 6

In a mixing vessel –> pigs
Pigs get infected with human and avian influenza, both replicating inside pig cells.
8 RNA segments of influenza recombine to create a virus that is not recognised by human immune system

Question 7

Antigenic shift + inability to transmit between people = ?

Answer 7

Dead end zoonoses

Question 8

How does influenza get into the human body?

Answer 8

Respiratory - penetrates mucous membranes and infects epithelial cells

Question 9

What is the receptor for influenza in humans?

Answer 9

Sialic acid

Question 10

What is the difference between how avian and human influenza enters cells?

Answer 10

Human sialic acid uses alpha2-6 link
Avian sialic acid uses alpha 2-3 link

Question 11

How can avian influenza use human sialic acid?

Answer 11

Mutation in haemaglutanin receptor binding pocket

Question 12

How does pH impact a viruses ability to infect humans?

Answer 12

Viruses are adapted to shed their capsule in low pH, as this is what happens when a lysosome forms around it upon entry to cell
However, URT is mildly acidic and aerosol transmission also lowers pH so virus needs a way to not shed its capsule prematurely

Question 13

List the 3 tools of pandemic response

Answer 13

Non pharmaceutical managment - isolation, social distancing etc
Antiviral drugs
Vaccines

Question 14

List drugs used in pandemic

Answer 14

Neurominidase inhibitor (destroy sialic acid)
Baloxavir (polymerase)

Question 15

What type of vaccine are the 2 current flu vaccines (one adult, one children)?

Answer 15

Adult = inactivated, purified haemaglutanin and NA
Kids = live attenuated, cold adapted (4 flu viruses)

Question 16

How could a universal flu vaccine be created?

Answer 16

Creating ABs to the stem of haemagluttanin as this is constant across all flu strains, where as the spike is variable

Question 17

What is a coronavirus?

Answer 17

RNA genome of positive sense in 1 piece, non segmented
30kb (large)
nidovirales type

Question 18

What R do coronaviruses bind to?

Answer 18

ACE2

Question 19

What are the wild reservoirs of coronaviruses?

Answer 19

Wild horseshoe bats

Question 20

Describe disease course of covid

Answer 20

day 0 = infected
day 3 = infectious
day 5 = symptomatic
EITHER
day 8 = non infectious
OR
days 7-10 = disseminated pathology

Question 21

What did the recovery trial discover?

Answer 21

Dexamethasone would reduce death by 1/3 in the sickest patients, but made it worse in mild patients

Question 22

Name 2 potential drug Tx for covid

Answer 22

Molnupiravir
Paxlovid
(monoclonal ABs)

Question 23

What type of vaccine is moderna?

Answer 23

Modified mRNA encoding stabilised spike