Lecture 6- Prevention and treatment of viral disease

Question 1

What is the difference prophylaxis and therapy?

Answer 1

PROPHYLAXIS= preventing the disease before the etiological agent is acquired by vaccination or prophylactic drugs
THERAPY+ tranig disease after infection of host

Question 2

What are the two mechanisms of defence against viruses?

Answer 2

Vaccines- prophylactic

Antiviral drugs- Therapeutic

Question 3

Why was the smallpox vaccine lead to the eradication of smallpox?

Answer 3

• No animal reservoir
• No latent or persistent infection
• easily recognisable disease
• vaccine effective against all strains
• Properties of vaccine: potency, low cost, abundance, heat stability, easy administration

Question 4

What are the different types of vaccines? Give examples of viruses along with them

Answer 4

• live attenuated virus vaccine (influenza, MMR, Polio, smallpox, varicella)
• inactivated virus vaccine (HepA, Rabies, Japanese encephalitis)
• Fractionates subunit vaccine ( Influenza)
• live virus vector vaccine
• DNA vaccine

Question 5

How do you generate an attenuated virus?

Answer 5

1) Pathogenic virus isolated from patient and grown in human cultured cells
2) Virus used to infect permissive cell line (monkey cells)
3) Virus mutates and evolves exclusively to monkey cells
4) Virus can’t grow in human cells =vaccine

Question 6

What are the pros and cons of a live vaccine?

Answer 6

PROS: 
- rapid, broad ,long lived immunity
- dose sparing
- cellular immunity
CONS:
- requires attenuation
- may revert

Question 7

How are inactivated vaccines generated?

Answer 7

• Destroy genome

- host has immune response to virus surface proteins

Question 8

What are the pros and cons of inactivated vaccines?

Answer 8

PROS:
- safe
- can be made from wild the virus
CONS:
- needs frequent boosting
- high doses needed

Question 9

Which two viruses have both live and attenuated vaccines?

Answer 9

Influenza

Poliovirus

Question 10

What are the two forms of the poliovirus?

Answer 10

• Salk inactivated vaccine

- Sabin live attenuated vaccine (not for immunocompromised individuals)

Question 11

What are the two forms of the influenza vaccine?

Answer 11

• Inactivated virus/ HA subunit

- LAIV (FluMIST)- for children

Question 12

How are recombinant attenuated virus vaccines synthesised?

Answer 12

• remove gene for virulence
• gene for receptor binding proteins and capsid remains
• immuogen but not pathogenic

Question 13

What sort of vaccine is rotatrix and which virus is it used against?

Answer 13

Rotavirus (death by diarrhoea and vomitting)

- live attenuated rotavirus recombinant vaccine

Question 14

What are the criteria for administering rotatrix?

Answer 14

• Can cause intussusception (bowel blockage) in babies older than 3 months
• only given to babies under 15 weeks

Question 15

Name some subunit vaccines, the subunit they contain and the virus they target

Answer 15

1) Gardasil and Cervarix–> papilomavirus–> virus like particles from recombinant coat proteins
2) HBV vaccine –> Hep B –> sAG cloned and expressed in yeast

Question 16

What sort of vaccine is the shingles vaccine and who is it administered to?

Answer 16

Live attenuated vaccine

- for those aged 70 or 79

Question 17

What might vector Ebola G proteins in the Ebola vaccine?

Answer 17

Chimpanzee adenovirus

VSV

Question 18

What are the three different types of antiviral treatments?

Answer 18

1) Interferons to induce the hosts natural antiviral response
2) Drugs with specific antiviral capacity
3) Treatment to alleviate symptoms

Question 19

Name a specific group of antiviral drug and briefly describe how they work

Answer 19

Nucleoside analogues

• nucleoside incorporated into DNA
• lacks 3’ OH
• prevents phosphodiester bond formation

Question 20

Name a specific nucleoside analogue and briefly describe its mechanism of action

Answer 20

Acyclovir

• activated in virus infected cells
• higher affinity for Viral DNA polymerase than host cell polymerase
• maps to thymidine kinase

Question 21

Name the antivirals used against influenza

Answer 21

Amantadine, Zanamivir, oseltamivir

Question 22

Name another group of antivirals and how they work. Give a couple of examples of antivirals within this group

Answer 22

Neuraminidase inhibitors (NA are influenza surface proteins which cleave sialic acid and allow the exit of influenza from its hot cell)
- sialic acid, relents, tamiflu

Question 23

What are the different stages of the HIV replication cycle that antivirals target?

Answer 23

1) Binding and ENTRY inhibitors
2) REVERSE TRANSCRIPTION inhibitors
3) INTEGRATION inhibitors
4) Transcription and translation to proteins (PROTEASE inhibitors)
5) Transcription to replicate genome
6) Virion assembly
7) Budding and exit

Question 24

What was the initial treatment for HCV? what were the disadvantages of this treatment?

Answer 24

• Interferon treatment wit ribavirin
• only effective in 50% patients
• unpleasant side effects

Question 25

What were the two drugs which developed against HCV? what were the consequences of it?

Answer 25

Protease inhibitors- telaprivir and boceprivir

–> resistant mutants generated by monotherap y –> Combination therapy with IFN and RBVN

Question 26

What is the immunisation strategy for ebola?

Answer 26

1) vector vacine: G protein carried on a different virus
2) Passive vaccine
- Zmapp (3 MABs)
- Serum therapy from survivors