Treatment, Prevention, Control of Viral Diseases Flashcards
How do Neuraminidase inhibitors prevent the release of virus?
Prevent release of virus and spread of virus because hemagglutinin of virus is still bound/attached to the sialic acid containing receptors on surface of infected cell.
Dry heat sterilization method
Hot air oven, at least two hours at 160c
Antimicrobial Chemotherapy
Treatment of infectious diseases by drugs (chemical compounds) that are inhibitory or lethal to the pathogenic microbe
Resistance to Amantadine occurs by
Changes in amino acids that line the M2 channel, changes prevent the drug from plugging the channel
Differentiating Infected from Vaccinated Animal -DIVA
Vaccination with only live attenuated vaccines leads to a population of an antibody response that does not differ from the antibody response developed after natural infection.
Use of DIVA marker vaccines have a portion of the pathogen - less antigens than natrual strains
Antiviral Drugs
Class of medication used specifically for treating vial infections
Examples of Nucleoside Analog Reverse Transcriptase Inhibitors (NRTI’s)
Zidovudine (ZDV) / Azidothymidine (AZT)
Didanosine (ddI)
Targets for anti-retroviral therapy
Reverse transcriptase
Protease
Integrase
Fusion
Ways that live-attenuated virus vaccines are produced
Produced from naturally occuring attenuated viruses
Produced by attenuation of viruses by serial passage in cultured cells
Produced by attenuation of viruses by serial passage in heterologous host
Produced by attenuation of viruses by selection of cold-adapted mutants and reassortments
Types of non-replicating virus vaccines
Vaccines produced from inactivated whole virions
Vaccines produced from purifed native viral proteins
Internal Farm Biosecurity
Measures taken to combat spread of an infectious disease within the farm
Synthetic tricyclic amine of the adamantane family
Acts as both antiviral and anti-parkinson drug
Amantadine
Moist Heat Sterilization Method
Use of steam
Autoclave heated to 121c for at least 15 min at 15psi
T/F - Acyclovir is nontoxic to uninfected host cells
True
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Herpesvirus thymindine kinase and herpes virus DNA polymerase are not found in uninfected cells
Mechanism of ZDV / AZT
Resembles thymine deoxyribonucleotide triphosphate, reverse transcriptase cleaves two phosphates and inserts AZT monophosphate inot the cDNA that is being synthesized from viral RNA
Antisepsis
Application of a liquid antimicrobial chemical to skin or living tissue to inhibit or destroy microorganisms
Major membrane glycoproteins found on the surface of influenza virus
Neuraminidase (NA)
Hemagglutinin (HA)
Sterilization
Process that destroys or eliminates may or all pathogenic microorganisms, except bacterial spores on inanimate objects
Compared to antibiotics there are (more/less) antivirals available
Less
Mechanism of action of Amantadine
- Compound clog M2 channel and prevent it from pumping protons into the virion
- Viral RNAs remain bound to M1 and cannot enter nucleus
Non-Replicating Virus Vaccines
Vaccines produced from inactivated whole virions
Amantadine inhibits the replication of most strains of what virus
Influenza A viruses
Farm Biosecurity
Comprises all measures taken to minimize the risk of the introduction and spread of infectious agents
General farm biosecurity measures
Housing and management
All in All out housing system
Vermin and bird control
Purchasing policy
Visitor policy
Mechanism of Action of Acyclovir
- Acyclovir molecules → Acyclovir monophosphate by thymidine kinase enzyme
- Host cell adds two phosphates to acyclovir triphosphate. Transported to the nucleus
- Two phosphates are cleaved by virus to form acyclovir monophosphate
- Acyclovir monophosphate incorporated into growing DNA strand in place of a G base by Herpes Simplex DNA polymerase enzyme
- DNA stops growing - lacks attachment point necessary for insertion of additional nucleotides
Applies to animals/ persons who are known to be ill with contagious disease
Isolation
Major toxicities of AZT/ZDV
Anemia
Granulocytopenia
Applies to those who have been exposed to contagious disease
Quarantine
Antiviral Drugs
Drugs that interfere with the ability of a virus to infiltrate a target cell or target different stages of replication/synthesis of components required for replication of the virus
Live- Attenuated Virus Vaccine
Vaccines produced from naturally occurring attenuated viruses
Examples of Neuraminidase inhibitors
Oseltamivir (Tamiflu)
Laninamivir
Zanamivir
Peramivir
Acyclovir
Antiviral activity primarily restricted to herpesvirus
Administration as a prodrug, inactive form
Requires virus enzymes in infected host cell to convert itself into active form, which then interferes with virus replication
Mechanism for Resistance of Acyclovir
Absent production of viral thymidine kinase due to mutation in virus genome
Partial decrease in the production of viral thymidine kinase
Altered viral thymidine kinase substrate specificity that results in phosphorylation of thymidine
Mutations in viral DNA polymerase that causes decreased binding of acyclovir-triphosphate to viral DNA polymerase
4 “w” of Immunization
Where
When
Who
Why
Features of a good vaccine
Safe to use
Effective against diverse strains of same pathogen
Few side effects
Give long lasting, appropriate protectio
Easy to administer
Inexpensive
Benefits outweigh the risk
Neuraminidase Inhibitors
Inhibit neuraminidase (NA) enzyme
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Synthesized by Influenza A and B viruses
Antivirals can act on what processes of viral replication
Receptor binding
Uncoating
Nucleic acid and protein synthesis
Assembly
Release
Modulate immune system
Family of nucleoside ananlog reverse transcriptase inhibititors (NRTIs)
Resembles thymine deoxyribonucelotide - triphosphate
ADV / AZT
Antiviral chemotherapeutic agents are not common in veterinary practice because
High cost of development
Restriction to a single virus and specific animal species
Difficulty in development of broadspectrum with low cytotoxicity
Absence of rapid diagnostic techniques
Amantadine inhibits the replication of influenza A viruses by what mechanism?
Blocking uncoating of the virus
Antibiotics
Types of medications that destroy or slow down the growth of the bacteria
External Farm Biosecurity
Measures taken to prevent an infectious disease from entering or leaving the farm
Disinfection
Process that eliminates many or all pathogenic microorganisms, except bacterial spores on inanimate objects
Viral infection stimulates what part of the immune system
Interferon
Antimycotics
Medications used to treat fungal diseases
Many agents that interfere virus replication are toxic to the cell because
Viruses are intimately dependent on the metabolic pathways of their host cell for their replication
Oseltamivir - Tamiflu
Prodrug that after its metabolism in the liver, releases an active metabolite that inhibits neuraminidase
Sterilization Methods
Moist Heat
Dry Heat
Chemical methods
Radiation
Sterile Filtration
Decontamination
Process or treatment that renders a medical device, instrument or environemental surface safe to handle
Seconary mechanism of Amantadine to stop viral replication
pH change that result from M2 inhibition alter the conformation of hemagglutinin during its intracellular transport later in replication
Interferons
Class of proteins that has antiviral effects and modulate functions of the immune system
Antiparasitics
Class of medications which are indicated for the treatment of parasitic diseases
Mechanism of Uncoating of Influenza virus A
- Endosomal vesicle containing virus particle move toward cell nucleus causing pH to drop
- Viral HA protein undergoes conformational rearrangement
- Viral RNAs released into cytoplasm and transported to nucleus
- Viral RNAs bound to M1 protein
- M1 forms a shell that underlies the lipid membrane
- Viral M2 protein form channel to pump protons from endosme into interior virion
- Protons lower pH releasing viral RNA from M1 protein
Acyclovir can be used in the treatment of
Herpesvirus infections
Feline Herpesvirus 1
Equine Herpesvirus 1
