Dugga 3 - Antivirals

Question 1

What are zoonoses?

Answer 1

Viruses that can be transmitted from animals and insects to humans

Question 2

How can viruses be transmitted

Answer 2

Airborn
Tick born
Physical contact
Food-borne
Water-borne

Question 3

How can a virus be viewed in simple terms?

Answer 3

Protein package transmitting foreign nucleic acid between host cells

Question 4

Virus contain either RNA or DNA, can they contain both?

Answer 4

No
They contain one or more molecules of either RNA or DNA

Question 5

Can viruses contain both single and double stranded RNA or DNA

Answer 5

Yes, either ssRNA, dsRNA, ssDNA or dsDNA

Question 6

What is the protein coat called that protects the viral nucleic acid?

Answer 6

capsid

Question 7

What are capsids made up of?

Answer 7

Protein subunits called protomers

Question 8

What is a nucleocapsid?

Answer 8

A capsid containing nucleic acid

Question 10

How does vaccination work

Answer 10

Introducing the body to foreign material which bears similarity to some component of the virus but lacks its infectious nature

Question 11

What is the body’s response to a vaccine

Answer 11

It has the opportunity to recognise the molecular fingerprint of the virus (antigens) and is therefore primed to attack

Question 12

Why is it difficult to make a vaccine against HIV?

Answer 12

Because of rapid gene mutations in the viruses resulting in constant changes to the amino acid composition of the glycoproteins normally present on viral surface

Question 13

What triggers the immune system?

Answer 13

The glycoproteins on the viral surface. Therefore any changes in these will lead to the virus being disguised

Question 14

What is viral genomics?

Answer 14

The full genome of any virus can now be quickly determined and compared with other viruses

Question 15

What are good drug targets for antivirals?

Answer 15

Proteins that are important in the life cycle, bear little resemblance to human proteins, common to a variety of virus and important to early stages of the viral life cycle

Question 16

What do antivirals usually act against?

Answer 16

HIV, herpes virus, hepatitis b and hepatitis c

Question 17

Are there most antiviral drugs available against DNA or RNA viruses?

Answer 17

DNA

Question 18

How does aciclovir work?

Answer 18

It is a prodrug. It cab bind to DNA polymerase and inhibit it. Aciclovir can be added as a nucleotide to the growing DNA chain and then the chain cannot be extended any further

Question 19

Does aciclovir act as a chain terminator?

Answer 19

Yes

Question 20

Are nucleoside analogues prodrugs?

Answer 20

Yes

Question 21

How do nucleoside analogues show selectivity of virally infected cells over normal cells?

Answer 21

They are taken up more effectively into virally infected cells and their triphosphate show selective inhibition for viral DNA polymerases

Question 22

Have inhibitors of tubulin polymerisation been used against DNA viruses?

Answer 22

Yes

Question 23

What is a provirus?

Answer 23

A virus that can lay dormant in host cell DNA until it is activated by cellular processes

Question 24

Why does HIV have to be treated with a combination of drugs?

Answer 24

The virus undergoes mutations very easily and so can rapidly develop resistance. If only using one drug it will lead to, long term, select the mutated virus which is resistant. Need a combination of reverse transcriptase and protease

Question 25

What is an NRTI

Answer 25

Nucleoside reverse transciptase inhibitor

Question 26

What is NNRTI

Answer 26

Non nucleoside reverse transciptase inhibitor

Question 27

What is a PI?

Answer 27

Protease inhibitor

Question 28

How do non nucleoside inhibitors work?

Answer 28

Act as enzyme inhibitors by binding to an allosteric binding site

Question 29

How does the protease enzyme look?

Answer 29

A symmetrical dimeric structure consisting of two identical protein subunits

Question 30

What are the names of the two glycoproteins of flu?

Answer 30

HA haemagglutinin and NA neuroaminidase

Question 31

What does HA do?

Answer 31

Binds to the sialic acid moiety of glycoconjugates on the surface of host cells leading to cell uptake

Question 32

What does NA do?

Answer 32

Catalyses the cleavage of sialic acid from glycoconjugates. Aids the movement of the virus

Question 33

Are HA and NA antigens for the flu virus?

Answer 33

Yes

Question 34

Why are new flu vaccines required each year?

Answer 34

Because the influenza A virus readily mutates proteins

Question 35

How do the adamantanes work?

Answer 35

Inhibit influenza A by blocking a viral ion channel protein