Infections - Antiviral

Question 1

Common characteristics of Viruses ?

Answer 1

Acellular ( Lack cellular structure) submicroscopic, AND. obligate intracellular parasites - Cannot reproduce on own and rely on the host cell machinery for replication. They contain either DNA or RNA, NOT both

Question 2

What are Antiviral drugs ?

Answer 2

Drugs that interfere SELECTIVELY with a KEY
virus replication step (effective) without
affecting the host cell (viable and safe)

Question 3

Difference between Virus targeting and Host cell targeting Antiviral drugs ?

Answer 3

Virus targeting- Target viral enzymes/Proteins. E.g Sofosbuvir -Hepatitis C.

Host targeting- Target host cell receptors/ Pathways exploited by viruses e.g Maraviroc - HIV.

Question 4

Adv/Disadvantage of Virus targeting drugs

Answer 4

• Selectively toxicity towards VIRUS + lower risk to host
• More viral mutations > greater drug resistance

Question 5

Adv/Disadv of cell host targeting drugs

Answer 5

• Broad spectrum effect (Targets multiple viruses)
• REDUCED specificity (more SIDE EFFECTS)

Question 6

What is the MOA of HIV entry inhibitors ?

Answer 6

Maraviroc- HIV entry inhibitor, binds to CCR5 receptor. Prevents Virus entering T cell. ONLY effective against CCR5 tropic HIV.

Question 7

What are HIV Fusion entry inhibitors ?

Answer 7

BLOCK fusion of viral envelope with host cell membrane by acting on gp41 proteins.. Preventing Virus entering cell. E.g. Enfuviritide.

Question 8

What do M2 protein inhibitors do ? (Influenza therapy)

Answer 8

• Block M2 PROTEIN in influenza virus. Prevents virus UNCOATING +RELEASING genome into host cell.
• Only effective against Influenza A

Question 9

How do viral genome replication inhibitors work ? (HCV - Sofosbuvir)

Answer 9

Inhibit viral Polymerase enzymes. Prevent virus replicating it’s genome + using viral transcription to new genome.

Question 10

How do NRTI’s (HIV) work ?

Answer 10

• Mimic natural nucleotides.
• Incorporated into viral RNA/DNA during genome replication
• Once incorporated, causes erros in chain (mutations)
• Require activation

Question 11

How do NNRTI’s work (HIV) ?

Answer 11

• Bind to viral polymerases at allosteric
  sites
• Not incorporated in viral rna/dna
  -Allosteric inhibition, therefore causes conformational changes to enzyme making it INACTIVE.

Question 12

How do HIV integrase inhibitors work ?

Answer 12

HIV integrase inhibitors prevent integration of viral cDNA into host cell’s genome.

Question 13

How do protease inhibitors work ?

Answer 13

Block HIV/HCV protease enzyme, preventing maturation of viral proteins necessary for production of new viruses

Question 14

How do Neuraminidase inhibitors work (Influenza ) ?

Answer 14

prevent release of new influenza virus particles from infected host cell by blocking the neuraminidase enzyme