Antivirals, Antimalarial and Antifungals

Question 1

Differences between DNA viruses and RNA viruses

Answer 1

DNA viruses contains DNA genome but RNA viruses contain RNA genome. DNA viruses replication is mediated by DNA polymerase but RNA viruses replication is mediated by RNA polymerase (reverse transcriptase)

Question 2

Examples of DNA viruses

Answer 2

Herpes, Hepatitis B, Adenovirus

Question 3

Examples of RNA viruses

Answer 3

HIV, Influenza, Corona

Question 4

Characteristics of a virus

Answer 4

Not classified as living organisms as they are not cellular ( lack enzymes,no protein synthesis)
Compact structure
Inactive outside host cell
Molecules on the surface impart attachment specificity
Multiply by taking control of the host cells genetic material

Question 5

1st pathological mechanism of a virus

Answer 5

Adsorption: the virus attached to its host cell by specific binding

Question 6

2nd and 3rd pathological mechanism of a virus

Answer 6

PENETRATION: virus is engulfed into a vesicle and its envelope is UNCOATED = freeing the viral genome into the cell cytoplasm

Question 7

4th pathological mechanism of a virus

Answer 7

SYNTHESIS: replication and protein synthesis, the host cell synthesizes the basic components of new viruses

Question 8

5th pathological mechanism of a virus?

Answer 8

ASSEMBLY: viral spike proteins are inserted into infected host cell membrane. The nucleocapsid is formed RNA and capsomers

Question 9

6th pathological mechanism of a virus

Answer 9

RELEASE: enveloped viruses released off membrane = carrying away an envelope with the spikes. The virus is ready to infect

Question 10

Target and mechanism of Maraviroc?

Answer 10

Chemokine Receptor Antagonists and acts as a competitive antagonists. targets viral fusion/absorption

Question 11

Target and mechanism of enfuvirtide?

Answer 11

Targets viral fusion/absorption. Inhibits viral fusion with the host CD4 cell membrane

Question 12

Target, mechanism of amantadine and indication?

Answer 12

Synthetic amine which blocks M2 ion transport channel (proton pump) —> prevents VIRAL UNCOATING. Indication: Influenza A

Question 13

Target, mechanism of acyclovir and indication?

Answer 13

Viral DNA polymerase inhibitor —> terminates viral DNA chain elongation (replication). Indication: Herpes infection ( cold sores,genital herpes,chicken pox,shingles)

Question 14

Target, mechanism of zidovudine and indication?

Answer 14

Nucleoside reverse transcriptase inhibitor (NRTI) —> blocks the binding of incoming nucleotide —> chain termination. Indication : HIV

Question 15

Target, mechanism of efaverenz and indication?

Answer 15

Non-nucleoside reverse
transcriptase inhibitor (NNRTI) —> blocks the enzyme without the need for phosphorylation. Direct binding = activity loss. Indication : HIV

Question 16

Target, mechanism of protease inhibitors (e.g ritonavir,lopinavir) and indication?

Answer 16

Directly bind to the active site of viral protease —> block cleavage of viral proteins to functional conformations = production of immature non-infectious viral particles (VIRAL ASSEMBLY)

Question 17

What is the pre-erythrocytic cycle?

Answer 17

An infected female mosquito bites a person transmitting the plasmodium falciparum parasite, in the form of SPOROZOITES

Question 18

What do sporozites do?

Answer 18

Reach the liver and multiply within the hepatocytes without causing symptoms

Question 19

What is the erythrocytic cycle?

Answer 19

Sporozites become MEROZOITES, they enter the bloodstream and invade RBCs. MEROZOITES mature into TROPHOZOITES. Trophozoites mature into schizonts

Question 20

What do schizonts do?

Answer 20

They multiply asexually until the cells burst = allowing newly formed merozoites to invade more RBCs

Question 21

What is the exo-erythrocytic cycle?

Answer 21

SPOROZOITES enter hepatocytes and form hypnozoites. Dormant forms could reactivate after months/years = relapse

Question 22

Signs and symptoms of malaria?

Answer 22

Headache, cough, vague pains in joints, fever, nausea/vomitting,diarrhoea, cyanotic lips and nails

Question 23

What antimalarial is safe in pregnancy?

Answer 23

Proguanil ( + 5mg folic acid in 1st trimester)

Question 24

Drug class and MOA of proguanil?

Answer 24

Biguanide and is a folate antagonist

Question 25

Drug class and MOA of atovaquone?

Answer 25

Ubiquinone analogue and works by targeting mitochondria

Question 26

Structural features of fungi

Answer 26

Cell wall made from chitin
Layer of mannoproteins
Layer of beta-glucans
Cell membrane (ergosterol)