Prevention and treatment of viral disease COPY Flashcards
Define prophylaxis.
Preventing the diseases before the aetiological agent is acquired, by vaccination or giving the drug before infection
What are the four broad types of virus vaccines?
- Live Attenuated
- Inactivated
- Purified Subunit
- Cloning
Describe each of the types of virus vaccines.
Live Attenuated – live virus has its virulence reduced and then is administered to the patient
(mild infection)
Inactivated – the virus is taken and its genome is destroyed so that it is still stimulates a response but can no longer be infectious – given with adjuvant
Purified Subunits – the viral genome is taken and treated with proteases which chops it into small pieces. These subunits have antigens that can trigger an immune response.
Cloning – viral genome is cloned in a bacterium and the copies of the genome are either:
Injected into people
Put into virus-like particles
A new virus is made with a little segment of virulent material from the original virus
State what type of vaccine has been produced for each of these diseases:
Polio – inactivated + live attenuated
Smallpox – live attenuated
Rubella – live attenuated
Hepatitis B – cloned subunit
Influenza – inactivated + live attenuated
HPV – cloned subunit
How are Live Attenuated Vaccines made?
The virus is passed through the wrong type/wrong species of cells this makes the virus evolve and change its virulence
e.g. if a virus is passed through monkey cells then it will become a monkey virus and it will no longer be as virulent to humans
What are some differences between live attenuated vaccines and inactivated vaccines?
- Live attenuated vaccines give rapid, broad, long-lived immunity, dose sparing
- Inactivated vaccines often require boosters, high doses needed, safe
What types of vaccines exist for influenza?
Purified subunit vaccine
Live-attenuated (nasal spray)
What types of vaccines exist for polio?
SALK – inactivated
- preparation of virus has been treated so it can no longer replicate
- not a good vaccine because it needs a large dose
SABINE – live attenuated
- this is much better
- however if you give it to someone immunosuppressed they will have the persistent virus
How are recombinant attenuated virus vaccines made?
- Pathogenic virus genome typically consists of receptor-binding gene, virulence gene and capsid protein genes
- you can either mutate the virulence gene or delete the virulence gene
- You then get a virus which is IMMUNOGENIC but NOT VIRULENT
What type of vaccine does rotavirus have?
Live attenuated reassortant
only given to babies as it can cause bowel blockage in older babies
Give two examples of subunit vaccines.
HPV
Hepatitis B Virus
What is the best available broad antiviral therapy and what are the limitations of it?
Interferons they switch on a natural antiviral response
– it activates inflammation and fever and can make the patient feel even more ill
What are the two strategies for inhibiting influenza?
Blocking the M2 channel
Neuraminidase inhibition
Describe inhibition of the M2 channel in influenza.
- When endocytosed, influenza virus enters the endosome
- The low pH of the endosome opens the M2 channel allowing protons to move into the endosome and break the bonds holding together the protein capsid of influenza
- This allows influenza to uncoat and release its contents into the cytoplasm of the cell
- Adamantes (rimantadine and amanatadine) can fit in the M2 channel and prevent protons from moving in, thus meaning that the influenza is locked in its protein shell
Describe neuraminidase inhibition in influenza.
- Neuraminidase is usually produced by influenza to destroy sialic acid on the surface of the host cell thus meaning that the virus doesn’t bind to the same cell again
- By blocking neuraminidase you can limit the spread of the virus to other cells because it just binds to the same cell again and again
