Prevention and Treatment of Viral Disease Flashcards
Prophylaxis:
preventing didease pefroe agent acquired
Therapy:
treating disease after host infected
What are the different types of vaccine?
Live attenuated:
- natural virus with genome inside capsid - Virulence recued so only mild infection
Inactivated virus vaccine:
- take parental virus and treat with chemicals and head to destroy genome - No longer infectious but proteins still triggered
Purified subunit vaccine:
- original parental genome taken and treated with proteases to chop into little pieces - Subunits containing antigens trigger IS
Toxoid: made from toxin that has been made harmless
Conjugate: weak antigen covalently attached to strong antigen so stronger immunological response
How do you clone a virus?
- Live virus vector, DNA, virus like particles vaccines
- Part of original viral genome cloned inside bacteria
- Can put DNA into virus like particle
- May just inject viral DNA
- May make new virus doesn’t make people ill but has virulent material segment
How do you attenuate a virus?
- Isolate
- Grow
- Take culture and infect
- Adapt to other organism so no longer infects humans
What viruses have both live and attenuated vaccines?
- Influenza: inactivated virus with only spike proteins (HA)
- Polio
What are the two types of polio vaccine?
- SALK inactivated vaccine - treated so no longer replicated
- Not good vaccine need larger does
- SABINE live attenuated - better
How to make a recombinant attenuated virus vaccine?
- Pathogenic virus genome usually consists of:
- Receptor binding gene
- Virulence gene
- Capsid protein gene
- Can either mutate virulence gene or delete is so virus immunogenic but no virulent
How was smallpox eradicated?
- No animal reservoir
- No latent or persistent infection
- Easily recognized disease
- Vaccine was effective against all strains
- Potent, low cost, abundant, heat stable, easy administration
What are the pros of a live vaccine?
- Rapid
- Broad
- Long lived immunity
- Dose sparingly
- Cellular immunity
What are the cons of a live vaccine?
requires attenuations so may revert
What are the pros of an attenuated vaccine?
- Safe
- Can be made form any type
What are the cons of an attenuated vaccine?
- Requires frequent boosting
- Needs high dose
How to treat viral infections?
Interferon
How are viruses targeted?
target viral enzymes by acting as substrate analogues
What is a nucleoside analogues?
- Viruses need to replicate genome and add nucleosides to growing RNA chain
- Look like normal base but missing e.g acyclovir, Zidovudine AZT
- Modified nucleosides incorporated but lack 3’ hydroxyl group so chain terminates
What are neuraminidases?
- Produced by influenza
- Virus enters cell by binding to sialic acid during infections so replicating host cell gradually dies and new viruses bud
- Neuroamidiase moves to cell surface and destroys sialic acid (SA) so original cell less likely to be infected by daughter
- If inhibit neuroamidase enzyme latches back down to cell and won’t spread
What are drugs used in HIV treatment?
- NRTI
- NNRTI - bind to enzyme but not active site
- Integrase inhibitor
- Entry inhibitors
- Protease inhibitor
What are other forms of viral treatment?
- protease inhibitors (HCV and HIV)
- ion channel blockers (influenza)
- neuraminidase inhibitors (influenza)
