6 - Prevention and treatment of viral disease Flashcards Preview

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Flashcards in 6 - Prevention and treatment of viral disease Deck (15):

What is the difference between prophylaxis and therapy?

prophylaxis prevents this disease BEFORE the host is infected
therapy target the infection after it has infected the host


What is a live attenuated virus vaccine?

a natural virus with its genome inside a capsid, which has had its virulence reduced so it only produces a mild infection and stimulates the immune response


what is an inactivated virus vaccine?

take the parental virus, and treat with chemicals and heat to destroy the genome (so it is no longer infectious)
when injected into a person, the viral proteins will be recognised and an immune response will be triggered


What is usually added in an inactivated virus vaccine and why?

because getting an immune response from the vaccine is more difficult


what is a purified subunit vaccine?

original parental genome has been taken and treated with proteases to chop it into smaller pieces
these are subunits of the virus which contains antigens that can trigger an immune response


what are the cloned types of viral vaccines?

- live virus vector vaccine
- DNA vaccine
- virus-like particle vaccine


How can vaccines be produced from cloning?

parts of the original viral genome are cloned inside the bacteria
- the DNA can be put into virus-like particles e.g. HPV
- the viral DNA can be injected into someone
- a new virus can be made which doesn't make people ill but has a segment of virulent material from the original virus


How are viruses attenuated to make Live Virus Vaccines?

- isolate pathogenic virus from patient
- grow in human cells
- take cultured virus and infect monkey cells
- gradually the genome of the virus will adapt to the monkey cells and it will become a monkey virus
- the virus will now longer grow well in human cells


What are the pros and cons of live vaccines?

- rapid, broad and long-lived immunity
- dose sparing
- cellular immunity
- requires attenuation
may revert


What are the pros and cons of inactivated vaccines?

- safe
- can be made from wild virus type
- frequent boosting required
- high doses needed


Which virus has both live and inactivated vaccines available?

influenza, polio


How are recombinant attenuated virus vaccines made?

- pathogenic virus genomes are made up of a receptor-binding gene, virulence gene and capsid protein genes
- the virulence gene can either be mutated or deleted
- the resulting virus is IMMUNOGENIC but NOT VIRULENT


What do viral enzymes tend to target and what do they act as?

target viral proteins/enzymes
often acts as substrate analogues


What are the best antiviral drugs?

Nucleoside analogues


What are the advantages of acyclovir?

- very good antiviral because it is specific to virus infected cells
- administered as a pro-drug and it can only phosphorylated by the virus encoded enzyme THYMIDINE KINASE
- it has has a higher affinity for viral DNA polymerase than host DNA polymerase