Anti viral agents Flashcards
What is a virus?
Infectious obligate intracellular parasite.
Size of a virus?
10nm - 1μm
When talking about the shape and how a virus looks what term is used?
Virus morphology.
What is an enveloped virus?
Lipid bilayer membrane on outermost part of virus.
What is a non enveloped virus?
Only has a protein capsid on outermost part of virus.
Examples of non enveloped viruses?
Adenovirus, Picornavirus, Calicivirus.
Examples of enveloped viruses?
Measles virus and ebola virus.
Why do RNA and retro viruses lack proof reading capability?
They use their own RNA polymerases. These lack proof reading capability.
Why do RNA and retro viruses have a higher mutation rate?
Lack of proof reading.
What does segmentation of viral genome allow?
Segmentation of viral genomes allows exchange of intact genes between related viruses when they coinfect the same cell.
What does HIV use to bind to CD4 receptor?
gp120 (glycoprotein).
How does HIV replicate?
Binds to CD4 using gp120 receptor. Viral contents enter cell. Viral DNA formed by reverse transcriptase. Viral DNA inserted in human genome using an integrase. New Viral RNA is used as genomic RNA and used to produce viral proteins. New viral RNA and proteins move to cell surface to produce immature HIV. Budds out of cell.
How does influenza replicate?
Influenza enter cell by endocytosis. Single strand of RNA enters nucleus. RNA is replicated and mRNA is produced. mRNA leaves nucleus and is translated into viral proteins. RNA genomes and viral proteins go to cell surface join together and bud off.
What is the cytopathic effect?
Morphological changes in cells caused by viral infection
What is syncytia?
Fusion of multiple cells into a single multinucleated cell body. Viruses can cause this.
What technique can be used to detect viral genome?
PCR.
What technique can be used to detect viral antigen?
ELISA.
What do nucleoside analogues do?
Inhibit nucleic acid replication.
What is acyclovir?
Nucleic acid chain terminator. Guanosine derivative.
What is acyclovir missing in order to continue addition of nucleotides? What bond can’t be formed?
Lack of 3’ -OH prevents phosphodiester bond formation.
What allows for the specificity of acyclovir?
Only activated inside virus infected cells as it can only be phosphorylated by virus-encoded thymidine kinase present in herpes virus. Higher affinity for viral dna polymerase rather than host cell polymerase.
What does remdesivir treat?
Hepatitis C and SARS-COV-2
How does remdesivir treat hepatitis C?
Adenosine derivative. Cause chain termination 3 nucleotides downstream of incorporation by twisting DNA.
Amantadine treats what disease?
Influenza A.
How does amantadine work?
Blocks M2 channel protein. Influenza is locked in the endosome as H+ ions can’t enter M2 channel protein and so no uncoating of virus.
What has prevented amantadine from working?
A single point mutation in the M2 channel protein.
What are relenza and tamiflu?
Neuraminidase inhibitors.
How do neuraminidase inhibitors work?
Prevents sialic acid cleavage by inhibiting neuraminidase enzyme. Virus is stuck on cell.
Why is tamiflu better than relenza?
Chemistry of Relenza means the virus more readily acquires resistance
What does baloxavir treat and how?
Influenza. Inhibits PA endonuclease.
HIV antiviral drug mechanisms?
Fusion inhibitors, co receptor antagonists, Reverse transciptase inhibitors, integrase inhibitors, protease inhibitors (block maturation stage at end).
What is palivizumab?
Monoclonal antibody. Type of passive immunotherapy use to treat RSV (Respiratory syncytial virus).
What is dexamethasone and tozulizimab
Immunomodulators. Dexamethasone is a steroid that decreases inflammatory response and toculizimab inhibits IL-6.
Cure for HIV?
Transplant of bone marrow from a CCR5 delta 32 donor.
Why may you keep someone on a drug even if the virus has resistance to it?
Mutations acquired that gives resistance to drug lowers virulence.
