6 - SARS-CoV-2

Question 1

when was the first coronavirus discovered?

Answer 1

1931

Question 2

when was reverse genetics discovered?

Answer 2

2000

Question 3

what family doe the Sars-CoV-2 virus belong to?

Answer 3

Coronaviridae

Question 4

which members of the coronavirinae subfamily are known to cause infections in humans

Answer 4

alphacoronavirus and betacoronavirus

Question 5

SARS-CoV-1

Answer 5

• Spill-over reservoir unknown: civet cats -cull to break the chain
• Most transmission occurred in hospital setting (hubs)
• No transmission until 24-36h after symptoms, lack of asymptomatic cases -contract tracing effective

Question 6

SARS-CoV-2

Answer 6

• Spill-over reservoir unknown
• Widespread community transmission
• Possible abundant asymptomatic/mild cases

Question 7

SARS-COV-2 Genome

Answer 7

• Single-stranded
• non-segmented
• positive sense
• ~30 kb long genome. - encodes for 27 genes which are either structutral, non-structural, accessory proteins

Question 8

structural proteins

Answer 8

• Constitute the virion

* Include S, E, M, N

Question 9

non- structural proteins

Answer 9

• Not structural components of virion

* Include NSP1, NSP2, NSP3, NSP14 etc

Question 10

What is the role of non-structural proteins in SARS-COV-2?

Answer 10

They form a large compound that replicates RNA

Question 11

accessory proteins

Answer 11

• Produced only in infected cells

* Includes ORF3b, ORF6, ORF7a etc

Question 12

coronavirus virion and viral proteins

Answer 12

• ~125 nm diameter
• enveloped viruses
• Numerous surface-projected club-like spikes

Question 13

Functions of S protein

Answer 13

• Entry of SARS-COV-2 into cells
• Host tropism
• Protective immune responses (vaccines)
• Virulence – severity of the disease

Question 14

Functions of N protein

Answer 14

• Component of nucleocapsid
• Virus transcription efficiency
• Protective immune responses (vaccines)

Question 15

Functions of M protein

Answer 15

• Most abundant amongst structural proteins

* Assembly of virus particles

Question 16

Functions of E protein

Answer 16

• Smallest amongst all the structural proteins

* Virus assembly, and release

Question 17

What are the 4 stages of the SARS-COV-2 replication cycle

Answer 17

Fusion, replication, assembly and release

Question 18

What are the two ways in which SARS-COV-2 can enter the host cell?

Answer 18

• the virus will bind to the ACE-2 receptor and then the receptor is cleaved by TMPRSS2 and then the plasma membrane fuses with the virus
• the virus binds to ACE-2 and is endocytosed into the cell

Question 19

Why is omicron less severe than delta?

Answer 19

Omicron replicates in the upper respiratory tract meaning that the lungs do not experience the damage that they would with delta which replicates in the lungs

Question 20

Which types of immunity is important for long term protection against COVID?

Answer 20

Antibodies, CD4+ T cells and CD8+ T cells

Question 21

How is SARS-CoV-2 transmitted?

Answer 21

Droplets (e.g. coughing), aerosols (e.g. talking) or smear infection (e.g. on surfaces such as door handles)