L11: Immunisation

Question 1

Explain passive immunity

Answer 1

• short lived (half life of IgG ~3 weeks)
• hypogammaglobunlinaemia in infants as maternal IgG declines
• can be gained by plasma infusion (Ab from recovered patients)
• IgG can be infused every 2/3 weeks for immunodefieciency to maintain protection

Question 2

Explain active immunity

Answer 2

• exploits immunological memory
• secondary response is faster to develop, greater in magniutde and may be qualitatively better (e.g. higher affinity Ab)

Question 3

How can herd immunity protect an individual and the gen population

Answer 3

Disease declines if majority of population is immune

Question 4

Explain the pathology of measles

Answer 4

• highly infectious viral disease where patients develop fever and rash
• can cause ear infections ( which can lead to hearing loss), pneumonia (particularly in young kids), sub acute scelerosing panecephalitits (SSPE)

Question 5

What percentage range need to be vaccinated to prevent MMR outbreaks?

Answer 5

83-94%

Question 6

List the requirements for an effective vaccine

Answer 6

• vaccine being safe& stable
• high level of protection
• long lasting protection
• right type of response
• low cost
• easy to administer
• minimal side effects

Question 7

What are the 5 main typpes of vaccines?

Answer 7

• Inactivted: dead organisms
• Attenuated: live but virulence disabled organisms e.g. yellow fever
• Subunit: protein fragments e..g Hep B
• Toxoid: bacterial toxin e.g. tetanus
• Conjugate: something with low antigenic property covalently bound to something with high e.g. s. pneumoniae+ diptheria

Question 8

Name advantages of using live vaccines

Answer 8

• single dose effective
• may be given by natural route
• may induce local and sytemic immunity
• may induce right type of response

Question 9

Name cons of using live vaccines

Answer 9

• can revert to virulence
• possibility of contaminatin
• susceptible to inactivation
• causes disease in immunocompromised host

Question 10

How is polio caused?

Answer 10

By an enterovirus spread through the faceo-oral route

Question 11

Explain the cell biology of polio

Answer 11

Member of the picornaviridae: +ve sense RNA translated into large polypeptide which is cleaved post translation

Question 12

How do polio infections present?

Answer 12

Most infections are subclinical and are small # are accompanied by flu like symptoms

Question 13

How many strains of polio cause symptoms?

Answer 13

3

Question 14

Give examples of diseases that are treated with subunit vaccines

Answer 14

• hep B: surface Ag of virus
• pneumoccal polysacc: from the capsule of s. pneumoniae (pneumovax) & may get non responders
• tetanus toxoid: inactivated form of a protein exotoxin seecreted by bacteria

Question 15

Explain how subunit vaccines work

Answer 15

T dependent response

- MHC interaction with TCR ables T cells to help and stimulate B cells by production of their cytokine panel

Question 16

What is ‘reverse vaccinology’?

Answer 16

Where the whole genome is screened to identify proteins that could be used as vaccines
- used to develop vaccine against neisseria meningitidis group B

Question 17

What are other important considerations for vaccines?

Answer 17

• Importance of inducing ‘right type’ of immunity e.g. HIV may need to induce CTL response
• Wrong type of immune response may do more harm than good e.g. 1960s RSV vaccine

Question 18

What are adjuvants?

Answer 18

Substances administered with an Ag to promote immune response

• pure Ags often eliicit weak immune response
• enhances immune response by providing a ‘depot’ and by immunostimulatory properties

Question 19

Explain how adjuvants can act in the immune response

Answer 19

• Activate dendritic cells via TLRs or NLRs
• Cause release of endogenous danger singals
• Promote Ag uptake by dendritic cells, which can then locate their lymph nodes & help stimulate B and T cells
• Stimulate release of chemokines/ cytokines
• Promote cross presentation of exogenous Ag by class I MHC, geeting CD8 and CTL cells involced and produce those cytokines and engage with macrophages

Question 20

Adjuvants are licensed for use in humans and animals. True or false?

Answer 20

True, but they are not all interchangable

Question 21

Give examples of adjuvants used in animals

Answer 21

• Freunds adjuvant: oil in water emulsion, quite immunogenic and can cause bad localised reactions
• Freunds complete adjuvant: also contains mycobacteria and is v stimulatory

Question 22

What is ‘alum’?

Answer 22

Its the most commonly used adjuvant in humans

• contains aluminium containig compounds
• been shown to be better in stimulating Ab response (Th2) compared to Th1 mediated response