T & P & Control Of Viral Diseases Flashcards
Describe the treatment of viral diseases.
- Antiviral drugs
-interfere w the ability of a virus to infiltrate a target cell or target diff stages of replication/syn of components required for the replication of the virus - IS stim
-interferons = class of proteins w antiviral effect & modulate func of IS - Syn of antibodies or administration of natural antiserum (antibodies)
Describe Acyclovir.
-antiviral restricted to herpes virus
-prodrug, inactive
-synthetic nucleoside analog of deoxyguanosine
-requires virus enzymes in inf host cell to covert into active form -> then interferes w virus replication
TREATMENT OF:
1. Herpesvirus inf in humans
2. Feline herpesvirus 1 induced corneal ulcers
3. Equine herpesvirus 1 induced encephalomyelitis
Describe the mechanism of antiviral effect of Acyclovir.
-herpes simplex DNA polymerase enzyme incorporates the acyclovir mono phosphate into the growing DNA strand as if it were 2-deoxyguanosine monophosphate
-stop the growing viral DNA chain = further elongation of the growing viral DNA chain is impossible bc acyclovir monophosphate lacks the attachment point for insertion of additional nucleotides
-competitive inhibition of viral DNA polymerase = acyclovir tri phosphate compete w dGTPs for viral DNA polymerase
Describe how acyclovir is non toxic to the uninfected host cell.
-herpesvirus thymidine kinase & herpes virus DNA polymerase = viral enzymes & not found in uninfected host cells -> acyclovir cant be phosphorylated & incorporated into host DNA
=non toxic to uninfected host cells
Describe Amantadine & its mechanism of antiviral effect.
-inhibit replication of most strains of influenza A viruses by blocking uncoating of virus
MECHANISM:
-M2 ion channel is the target of the antiviral Amantadine
-compounds clog the channel & prevent it from pumping protons into the virion
-viral RNAs remain bound to M1 & cant enter the nucleus = virus replication inhibited
Describe neuraminidase inhibitors & their mechanism of action.
-syn by influenza A & B virus
>EX: oseltamivir (Tamiflu)
MECHANISM:
-block function of neuraminidase w NA inhibitors to treat influenza
-prevents release of virus & spread of inf as the HA of virus is still bound/attached to the sialic acid containing receptors on surface of already inf host cell
-inhibition of neuraminidase slows virus spread to give IS time to catch up & mediate virus clearance
Describe nucleoside analog reverse transcriptase inhibitors (NRTIs).
- Zidovudine (ZDV) or Azidothymidine (AZT)
-nucleoside analog of thymine i.e. resembles the deoxyribonucleotide containing the base thymine - Didanosine (ddI)
Describe the ZDV/AZT mechanism of action.
-competitive inhibition of reverse transcription activity = AZT-triphosphate competes w thymine deoxyribonucleotide triphosphate for reverse transcriptase
-insertion of AZT-monophosphate into cDNA blocks the growth of the cDNA being transcribed from the viral RNA by reverse transcriptase
*AZT has been shown to reduce CS in a FIV positive cats when administered at a dose of 10mg/kg BID SQ for 3wks
Describe proteases & protease inhibitors.
- Protease
-required to cleave the HIV poly proteins into functional proteins - Protease inhibitors
-inhibit protease -> HIV poly proteins cant be cleaved into functional proteins
-bind to active site of HIV protease & prevent the enzyme = HIV cant mature & non infectious virus made
Describe the prevention & control of viruses.
- Vaccination
A) live attenuated virus vaccines
B) non replicating virus vaccines
-vaccines made from inactivated whole virions
-vaccines made from purified native viral proteins
C) vaccines made by recombinant DNA & related technologies - Reducing contact
A) isolation = applies to animal/ppl who are known to be ill w contagious disease (show CS or test +)
B) quarantine = those who have been exposed to a contagious disease
-not effective w diseases involving chronically inf healthy shedder
-sep animal even if no CS or - test
C) culling
-sep & restrict movement of animals & proper disposal - Decontamination
A) decontamination = process that renders medical device, instrument, surface safe to handle
B) sterilization = destroy all forms of microbial life (even highly resistant pathogens like spores)
C) disinfection = elim many or all path except spores on inanimate objects (less effective)
D) antisepsis = liquid antimicrobial to skin to inhibit or destroy microorganisms - Sterilization methods
A) moist heat = autoclave
B) dry heat = hot air oven
C) chemical method = gas like ozone & ethylene oxide
D) radiation
-non ionizing = UV
-ionizing = gamma, X-RAYS
E) sterile filtration = microfiltration using membrane filters
Describe live attenuated virus vaccine types.
- vaccines made from naturally occurring attenuated viruses
- vaccine made by attenuation of viruses by serial passage in cultured cells
- vaccine made by attenuation of viruses by serial passage in heterologous hosts
- vaccines made by attenuation of viruses by selection of cold adapted mutants & reassortants
Describe differentiating infected from vaccinated animals.
‘DIVA’
-subunit marker vaccines (DIVA) have a portion of pathogen in vaccine (less antigens than natural strain)
-if antibodies to other parts/antigens of the pathogen not included in the vaccine are detected the animal has been inf w the path
-if only antibodies to the vaccine subunit/antigen detected then the animal has not been inf
*accompanying diagnostic test
