Dugga 3 - Antivirals Flashcards
What are zoonoses?
Viruses that can be transmitted from animals and insects to humans
How can viruses be transmitted
Airborn
Tick born
Physical contact
Food-borne
Water-borne
How can a virus be viewed in simple terms?
Protein package transmitting foreign nucleic acid between host cells
Virus contain either RNA or DNA, can they contain both?
No
They contain one or more molecules of either RNA or DNA
Can viruses contain both single and double stranded RNA or DNA
Yes, either ssRNA, dsRNA, ssDNA or dsDNA
What is the protein coat called that protects the viral nucleic acid?
capsid
What are capsids made up of?
Protein subunits called protomers
What is a nucleocapsid?
A capsid containing nucleic acid
How does vaccination work
Introducing the body to foreign material which bears similarity to some component of the virus but lacks its infectious nature
What is the body’s response to a vaccine
It has the opportunity to recognise the molecular fingerprint of the virus (antigens) and is therefore primed to attack
Why is it difficult to make a vaccine against HIV?
Because of rapid gene mutations in the viruses resulting in constant changes to the amino acid composition of the glycoproteins normally present on viral surface
What triggers the immune system?
The glycoproteins on the viral surface. Therefore any changes in these will lead to the virus being disguised
What is viral genomics?
The full genome of any virus can now be quickly determined and compared with other viruses
What are good drug targets for antivirals?
Proteins that are important in the life cycle, bear little resemblance to human proteins, common to a variety of virus and important to early stages of the viral life cycle
What do antivirals usually act against?
HIV, herpes virus, hepatitis b and hepatitis c
Are there most antiviral drugs available against DNA or RNA viruses?
DNA
How does aciclovir work?
It is a prodrug. It cab bind to DNA polymerase and inhibit it. Aciclovir can be added as a nucleotide to the growing DNA chain and then the chain cannot be extended any further
Does aciclovir act as a chain terminator?
Yes
Are nucleoside analogues prodrugs?
Yes
How do nucleoside analogues show selectivity of virally infected cells over normal cells?
They are taken up more effectively into virally infected cells and their triphosphate show selective inhibition for viral DNA polymerases
Have inhibitors of tubulin polymerisation been used against DNA viruses?
Yes
What is a provirus?
A virus that can lay dormant in host cell DNA until it is activated by cellular processes
Why does HIV have to be treated with a combination of drugs?
The virus undergoes mutations very easily and so can rapidly develop resistance. If only using one drug it will lead to, long term, select the mutated virus which is resistant. Need a combination of reverse transcriptase and protease
What is an NRTI
Nucleoside reverse transciptase inhibitor
What is NNRTI
Non nucleoside reverse transciptase inhibitor
What is a PI?
Protease inhibitor
How do non nucleoside inhibitors work?
Act as enzyme inhibitors by binding to an allosteric binding site
How does the protease enzyme look?
A symmetrical dimeric structure consisting of two identical protein subunits
What are the names of the two glycoproteins of flu?
HA haemagglutinin and NA neuroaminidase
What does HA do?
Binds to the sialic acid moiety of glycoconjugates on the surface of host cells leading to cell uptake
What does NA do?
Catalyses the cleavage of sialic acid from glycoconjugates. Aids the movement of the virus
Are HA and NA antigens for the flu virus?
Yes
Why are new flu vaccines required each year?
Because the influenza A virus readily mutates proteins
How do the adamantanes work?
Inhibit influenza A by blocking a viral ion channel protein
