Mechanism of Action of Anti Viral Drugs

Question 1

What is the basic structure of a virus?

Answer 1

small infective agents consisting of RNA or DNA enclosed in a protein coat

Question 2

how do viruses replicate?

Answer 2

they have no metabolic machinery and therefore use the host cell metabolic processes which they infect

Question 3

What do viruses use to attach to a host cell? What do they attach onto?

Answer 3

• polypeptides on the envelope or capsid

- bind onto normal membrane receptors for things like cytokines, neurotransmitters ore hormones

Question 4

what process do viruses use to enter the host cell once bound to the surface?

Answer 4

receptor mediated endocytosis

Question 5

What is the main target for entry inhibitors?

Answer 5

viral fusion with the host cell

Question 6

what are the 2 main entry inhibitors used?

Answer 6

entry inhibitor- Maraviroc

fusion inhibitor- Enfuviritide

Question 7

which viruses are entry inhibitors used against?

Answer 7

-retroviruses- HIV as an example

Question 8

How does HIV enter a host cell? What mediates its entry? What is the receptor? What are the co-receptors?

Answer 8

mediated by Env glycoprotein spike trimer of gp120 and gp41

receptor CD4 is required and a co-receptor CCR5 or CXCR4

Question 9

What is the mechanism of action of the entry inhibitor Maraviroc?

Answer 9

binds to co-receptor CCR5 preventing its interaction with gp120

Question 10

What is the mechanism of action of the fusion inhibitor Enfuviritide?

Answer 10

binds to gp41 and interferes with its ability to approximate the 2 membranes

Question 11

What are examples of drugs which prevent viral uncoating?

Answer 11

Amantadine and rimantadine

Question 12

What is the mechanism of action of the viral uncoating drugs?

Answer 12

block the M2 ion channel involved in virion uncoating following endocytosis

Question 13

What is the mechanism of nucleoside analogue chain terminators?

Answer 13

compete with natural substrate in DNA or RNA polymerisation.
Chain termination comes from not offering 3’-hydroxyl function at the 2’-deoxy ribose moiety required for the attachment of incoming nucleotide

Question 14

What type of drug are nucleoside analogues? what is their active form?

Answer 14

• prodrugs- requiring intracellular phosphorylation by viral and or cellular kinases converting them to
• 5’-triphosphates

Question 15

What is an example of a nucleoside analogue?

Answer 15

Aciclovir

Question 16

What sort of viruses are nucleoside analogues used to treat?

Answer 16

DNA viruses

Question 17

What is Aciclovir used against?

Answer 17

• herpes simplex virus: genital herpes simplex, herpes simplex labialis
• varicella zoster virus: chicken pox, shingles
• prevention of herpes viruses in immunocompromised patients

Question 18

How do nucleoside reverse transcriptase inhibitors work?

Answer 18

binds to the chain of DNA to being transcribed terminating it early rendering it useless since its incomplete

Question 19

now do no nucleotide reverse transcriptase inhibitors function?

Answer 19

bind to the reverse transcriptase enzyme itself and denature it so it can’t produce viral DNA

Question 20

What are examples of nucleoside RT inhibitors?

Answer 20

-lamivudine, abacavir, zidovudine stavudine

Question 21

what are examples of non nucleoside RT inhibitors?

Answer 21

delaviridine, efavirenz, etravirine, nevirapine

Question 22

What is the mechanism of action of protease inhibitors?

Answer 22

host mRNAs code directly for functional proteins.
virus specific protease then converts them into various functional proteins
protease does not occur in the host making it a target

Question 23

What are examples of protease inhibitors?

Answer 23

atazanvir, indinavir, lopinavir, ritonavir, saquinavir

Question 24

What are protease inhibitor used to treat?

Answer 24

hepatitis C virus

Question 25

Which protease inhibitors are used against hepatitis C?

Answer 25

Telaprevir and Boceprevir

Question 26

What is the function of HIV integrase?

Answer 26

mediates2 reactions: 3’ end processing of double stranded viral DNA ends.
strand transfer which joins viral DNA to host chromosomal DNA

Question 27

What are 3 examples of integrase inhibitors?

Answer 27

• Raltegravir
• Elvitegravir
• Dolutegravir

Question 28

What is the function of virus release inhibitors?

Answer 28

stops transmission within host by stopping transmission of virus from cell to cell

Question 29

what is an example of virus release inhibitors?

Answer 29

influenza Neuraminidase inhibitors

Question 30

what is the function of Neuraminidase during influenza infection?

Answer 30

NA- functions in influenza infection by cleaving sialic acid from cell surface so that newly made viruses are released and able to spread to uninfected cells

Question 31

how do NA inhibitors function?

Answer 31

replicate structure of sialic acid and bind to the active site on NA hence preventing its function

Question 32

what are 2 NA inhibitors?

Answer 32

Zanamivir

Oseltamivir

Question 33

What is an example of an immunomodulator and what is it used to treat?

Answer 33

• Peg interferon alpha

- Hepatitis C and B virus