Flashcards in Session 5 Deck (19):
What are the steps involved in the viral replication cycle?
1) Binding and adsorption of the virus to the host.
2) Virus endocytosed into the cell.
3) Viral RNA is synthesised and replicated to form new RNA.. Virus then assembled within the cell.
4) Virus is released by budding and then released from the cell.
What are the two steps involved for uncoating and successful transcription of viral RNA?
1) ATP-driven entry into the endosome, allowing fusion of the viral membrane to the internal endosomal membrane.
2) Protons must enter the virus via an M2-ion channel. The subsequent fall in pH allows the viral coat of the nucleocapsid to breakdown.
Which glycoprotein is required to prevent adhesion of viruses upon release?
Which type of influenza is the most serious and why?
Type A as they have multiple host species, and exhibit antigenic shift and drift.
What are M2 ion channel blockers?
E.g. Amantadine and Ramantadine. They prevent entry of protons into the virus itself, via the M2 ion channels. Used to treat influenza A.
Give two ADRs of M2 ion channel blockers.
Dizziness, GI disturbance, hypotension, confusion, insomnia, hallucinations.
Describe the role of neuramidase inhibitors.
Block virion release from the host cell membrane, hence they are unable to infect other host cells. Used to treat influenza A and B.
Give an example of a neuramidase inhibitor.
Zanamivir and Oseltamivir.
Give 2 ADRs of neuramidase inhibitors.
Headache, nose bleed, respiratory depression, bronchospasm.
Name the three antibiotic targets, and give an example of each.
DNA synthesis = Quinolones, e.g. Ciprofloxacin.
Protein synthesis = Aminoglycosides (Gentamicin), Macrolides (erythromycin) and Tetracyclines.
Cell wall synthesis = Beta-lactams (Penicillins, Cephalosporins and Carbapenems), Glycopeptides (Vancomycin).
What are common ADRs or antibiotics?
Diarrhoea, fever, nausea, vomiting and immediate hypersensitivity reactions.
Give the two mechanisms through which antibiotic resistance develops.
Intrinsic: due to gene mutation within the bacteria itself.
Extrinsic: resistance acquired from another bacterium passing on the information, e.g. via transformation, conjugation and transduction.
What is the difference between transformation and transduction in terms of antibiotic resistance?
Transformation = uptake of naked DNA
Transduction = movement of genetic material by bacteriophages.
What is conjugation?
cell-to-cell contact whereby chromosomal DNA is transferred from one bacterium to another, via plasmids.
Give two effects of antibiotic resistance.
1) Antibiotic inactivation
2) Alteration of target site
3) Alteration of metabolic pathways
4) Reduced intracellular antibiotic accumulation
Give two steps to avoid spread of resistance.
Preventing spread of recognised resistant bacteria.
What are the two major determinants of bacterial killing?
Time and concentration above the minimum inhibitory concentration.
What is time-dependent killing?
Some antibiotics are effective due to the extensive amount of time the antibiotic binds to the microorganism, and how long they spend above the minimum inhibitory concentration.