Control of Viral Population Flashcards
ways to control viral population
- Quarantine
- Good hygiene
- Changes in lifestyle
- Elimination of a vector
- Immunize the population
- Development and implementation of antivirals
ways to control outbreak
ID source/reservoir, clean-up, quarantine, immunization, etc.
Universal precautions when handling blood
assume contamination
Essential in hospital / health care settings in order to control viral disease
Limit contact, immunize health care workers, improve hygiene
disinfection for virus
70% ethanol, 15% chlorine bleach, autoclaving
is education (public, research) important for viral control
yeah
vaccines for virus
1) Inactivated (killed)
2) Live-attenuated
3) Subunit
4) DNA
difference between prophylactic and therapeutic
prophylactic - used to prevent contracting infection
therapeutic - used to treat once infection has been contracted
ways to prevent or treat viral populations
vaccines, antivirals, stimulate host innate immune system
ways to stimulate host innate immune system
– Interferon (induces synthesis of cellular proteins capable of inhibiting translation or transcription)
– Activate NK kills (agents that bind to toll-like receptors)
– Antibodies (natural or passive immunization)
what qualities make a vaccine good?
– Cheap (for majority of vaccines, new vaccines usually much more expensive)
– Used before discovery of viruses
– Result in decline of illness and death (polio, MMR, etc.) - humans and animals
– Eradication (smallpox)
what are live attenuated vaccines
LIVE virus particles that grow in the vaccine recipient but do not cause disease because the vaccine has been altered (mutated) to a non pathogenic form
examples of infections treated with live attenuated vaccines
Polio (Sabin), MMR, Yellow fever, Rotavirus, Varicella
what are inactivated vaccines
Preparations of the normal (wild type) infectious, pathogenic virus then rendered non-pathogenic usually by chemical treatment such as with formalin that cross- links viral proteins
example of infections treated with inactivated vaccines
Polio (Salk), Influenza, HepA
what are subunit viral vaccines
• Purified virus components
• Recombinant proteins that self-assemble
into Virus Like Particles (VLPs) and they help host form resistance
example of viruses treated with subunit
HepB, Quadrivalent HPV
what type of vaccine is gardasil
subunit
how does HPV vaccine work
– Recombinant L1 proteins that self-assemble into VLPs and is given before the onset of sexual activity
– ~100% protection from infection with vaccine HPV types
– Potential to prevent ~70% of cervical cancers,
~90% of genital warts
what is a DNA viral vaccine
- Usually harmless viruses into which a gene for a (supposedly) protective antigen has been spliced
- Protective antigen is then made in the vaccine recipient to elicit an immune response
how do antivirals work
they interfere with virus specific functions and interfere with cellular functions (preferably virus infected)
properties of antivirals
water soluble, taken up by cells, stable
what are antivirals not?
– toxic – carcinogenic – allergenic – mutagenic – teratogenic
what properties make a good medicine
- activity
- solubility
- oral bioavailability
- half life
- metabolic profile/toxicity
viruses treatable with antivirals
- Herpes simplex virus
- Varicella-zostervirus
- Cytomegalovirus
- Human immunodeficiency virus
- Influenza A and B viruses
- Respiratory syncytial virus
- Hepatitis B and C viruses
- Papillomavirus
- Picornavirus
goal of antivirals
virion disruption or inhibition of life cycle
how do antivirals block attachment hence blocking subsequent stages
– tends to be virus specific, more for prophylaxis
– neutralizing antibodies bind viral receptors prevent attachment of the virus to the host cell
how do antivirals block penetration
fusion inhibitors
how do antivirals block uncoating
– amantadine
how do antivirals block replication
– Nucleoside analogues: incorporated into viral genomes
– Get chain termination: analogues lack hydroxyl groups for linking of backbone
example of an antiviral that blocks replication
acyclovir
what is acyclovir used to treat
HHV I and HHV II infections
how does acyclovir work
it is a guanine analogue that uses viral thymidine kinase –> monophosphate (using host cell TK) –> diphosphate (using host cell TK) –> triphosphate
acyclovir triphosphate blocks DNA synthesis by chain termination which it does by inhibiting the function of viral DNA polymerase
nucleoside inhibitors of reverse transcriptase
Azidothymidine (AZT), ddI (nucleoside polymerase inhibitors)
what are non-nucleoside polymerase inhibitor example and how does it work?
Nevirapine - bind to various sites on enzyme
antiviral that blocks assembly and release
Protease inhibitors (Saquinavir, etc.)
how does Saquinavir (protease inhibitor) work
– Block cleavage of polyproteins
– HIV is dependent on proteolytic enzyme for full infectivity
– Drug-resistant strains > protease mutations
what causes resistance to antivirals
• Targeted enzyme changes • Mutations, deletions, substitutions • Replication rate – type of NA figures heavily here • Preventative measures against resistance – Rationale behind antiviral “cocktails”
examples of immunomodulators
• Interferons
– IFN-α: active against many viral infections
• Imiquimod
– Toll-like receptor ligand, stimulates innate responses to attack the virus infection (HPV)
examples of viruses that use interferons
Hep A, B, and C, HSV, HPV, and rhinovirus
