Antivirals, Antimalarial and Antifungals Flashcards
Differences between DNA viruses and RNA viruses
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)
Examples of DNA viruses
Herpes, Hepatitis B, Adenovirus
Examples of RNA viruses
HIV, Influenza, Corona
Characteristics of a virus
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
1st pathological mechanism of a virus
Adsorption: the virus attached to its host cell by specific binding
2nd and 3rd pathological mechanism of a virus
PENETRATION: virus is engulfed into a vesicle and its envelope is UNCOATED = freeing the viral genome into the cell cytoplasm
4th pathological mechanism of a virus
SYNTHESIS: replication and protein synthesis, the host cell synthesizes the basic components of new viruses
5th pathological mechanism of a virus?
ASSEMBLY: viral spike proteins are inserted into infected host cell membrane. The nucleocapsid is formed RNA and capsomers
6th pathological mechanism of a virus
RELEASE: enveloped viruses released off membrane = carrying away an envelope with the spikes. The virus is ready to infect
Target and mechanism of Maraviroc?
Chemokine Receptor Antagonists and acts as a competitive antagonists. targets viral fusion/absorption
Target and mechanism of enfuvirtide?
Targets viral fusion/absorption. Inhibits viral fusion with the host CD4 cell membrane
Target, mechanism of amantadine and indication?
Synthetic amine which blocks M2 ion transport channel (proton pump) —> prevents VIRAL UNCOATING. Indication: Influenza A
Target, mechanism of acyclovir and indication?
Viral DNA polymerase inhibitor —> terminates viral DNA chain elongation (replication). Indication: Herpes infection ( cold sores,genital herpes,chicken pox,shingles)
Target, mechanism of zidovudine and indication?
Nucleoside reverse transcriptase inhibitor (NRTI) —> blocks the binding of incoming nucleotide —> chain termination. Indication : HIV
Target, mechanism of efaverenz and indication?
Non-nucleoside reverse
transcriptase inhibitor (NNRTI) —> blocks the enzyme without the need for phosphorylation. Direct binding = activity loss. Indication : HIV
Target, mechanism of protease inhibitors (e.g ritonavir,lopinavir) and indication?
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)
What is the pre-erythrocytic cycle?
An infected female mosquito bites a person transmitting the plasmodium falciparum parasite, in the form of SPOROZOITES
What do sporozites do?
Reach the liver and multiply within the hepatocytes without causing symptoms
What is the erythrocytic cycle?
Sporozites become MEROZOITES, they enter the bloodstream and invade RBCs. MEROZOITES mature into TROPHOZOITES. Trophozoites mature into schizonts
What do schizonts do?
They multiply asexually until the cells burst = allowing newly formed merozoites to invade more RBCs
What is the exo-erythrocytic cycle?
SPOROZOITES enter hepatocytes and form hypnozoites. Dormant forms could reactivate after months/years = relapse
Signs and symptoms of malaria?
Headache, cough, vague pains in joints, fever, nausea/vomitting,diarrhoea, cyanotic lips and nails
What antimalarial is safe in pregnancy?
Proguanil ( + 5mg folic acid in 1st trimester)
Drug class and MOA of proguanil?
Biguanide and is a folate antagonist
Drug class and MOA of atovaquone?
Ubiquinone analogue and works by targeting mitochondria
Structural features of fungi
Cell wall made from chitin
Layer of mannoproteins
Layer of beta-glucans
Cell membrane (ergosterol)
