Immunisation

Question 1

3 types of vaccine

Answer 1

Live attenuated
Whole killed
Toxoids

Question 2

Two types of immunisation

Answer 2

Passive

Active/Vaccination

Question 3

Passive immunisation

Limitation

Advantages

Disadvantages

Answer 3

Pre-formed immunity from one organism to another

Requires antibody mediation

Immediate protection and effectiveness in immunocompromised hosts

Short-lasting
Possible transfer of pathogen
Serum sickness on transfer

Question 4

Passive immunisation - types of immunoglobulin and examples and source

Answer 4

Specific

• human tetanus Ig
• Human Hep B Ig
• VZV Ig

Normal immunoglobulin - HNIG
Prepared from pools of at least 100 donors
Antibody against MMR etc

Question 5

Active immunisation

Two types of vaccine

Answer 5

Vaccination
Live attenuated - weakened live strain of pathogen

Non-living - toxoid and whole killed

Question 6

Live attenuated

Mechanism

Advantages

Problems

Limitations

Answer 6

Organisms injected replicate within host and encourage immune response

• B cells produce plasma and memory cells for future infection
• organism is living and shape preserved –> more realistic
• lower/fewer doses needed
• immune response mimics closely
• better route of administration

• Could result in disease
• balance immunogenicity and attenuation
• reversion to virulence
• transmission
• same effect in the immunocompromised?

Question 7

Live attenuated examples

Bacterial

Viral

Answer 7

BCG - TB

Salmonella Typhi - given orally

Poliomyelitis - polio
Vaccinia - small pox
MMR

Some rely on herd immunity

Question 8

Herd immunity

Answer 8

Social concept of immunity passed on within a community. A certain percentage (80%) are immunised against a disease therefore chance of spread is significantly reduced

Question 9

Non-living vaccines

types

Answer 9

Toxoid
Whole killed

Rapid primary response - doesn’t cause disease

Question 10

Memory immune response chart

Antibody conc (y) by weeks (x)

Answer 10

Flat latent period post 1st exposure
Steep rise during immunisation period - antibody titre increases and levels of IgG and IgM increase
Levels decrease as infection ceases.

2nd exposure - shorter latent period and faster response
Steep curve as antibody conc increases exponentially
Greater increase in IgG

Question 11

Whole killed vaccines

mechanism

Problems and limitations

Examples
Bacterial and viral

Answer 11

Pathogens grown in vitro
Inactivated using toxic ages e.g formaldehyde

Protein or whole organism

Doesn’t cause infection
Antigens within induce immune response

• organism has to be grown in high quantity
• whole organism can cause excess reactogenicity
• immune response not always similar to real response
• need booster
• some bacteria expensive to grow
• adverse reactions

1. Tetanus toxin
2. DTP toxoid
3. Pertussis acellular as part of DTP
4. Cholera - heat killed to inactivate
5. Polio vaccine
6. Influenza
7. Hep A
8. Rabies

Question 12

Cell free toxoids/inactivated toxins

Answer 12

No cytology

Purely antigens/toxin

Question 13

Examples of pathogens without vaccine

Reasons for lack of vaccine

Answer 13

Malaria
HIV
Lyme disease
HSV

Mutation - shape change
Hard to grow
too many strains causing same disease
hard to obtain attenuated strains

Question 14

New approaches

Answer 14

Recombinant proteins
Synthetic peptides
Live attenuated vectors
DNA vaccines 
Polysaccharide-protein conjugates

Question 15

Recombinant proteins

Production
Advantages and problems
Examples

Answer 15

Genetically engineered from pathogenic or mammalian cells

Do not have to be grown in vitro
Not all proteins generate strong enough response
Hep B surface antigen

Question 16

Synthetic peptides

Production
Advantages
Problems

Answer 16

Machine made

Identifying epitopes is problem
Response may not be strong or broad enough

Question 17

Live attenuated vectors

Mechanism - what do they do

Examples and problems
Who is at risk?

Answer 17

Express protein within an attenuated vector e.g vaccinia for small pox, BCG and adenovirus
- bacterial DNA in viral vector –> inserts DNA encoding protective antigen –> displays bacterial antigens –> antibody response encouraged

Immunocompromised people at risk

Question 18

Vaccinia virus

Who is it given to

Answer 18

Smallpox

For immunocompromised

Question 19

DNA vaccines

Mechanism
Form of transmission

Advantage

Answer 19

Express protein from pathogen in mammalian expression plasmid
Injection –> protein expressed
More effective when followed with live vector boost

Avoids need to grow
DNA is cheap 
No live organism 
Poorer immunogenicity 
None on market

Question 20

T independent antigen based vaccines

Who responds poorly and examples of vaccines given

Answer 20

Difficult to vaccinate against
Coated in polysaccharide capsule - cannot be processed and displayed on MHC class II proteins
–> no T cell help

Low magnitude antibody response
Low affinity
Mostly IgM
Little or no boosting on secondary exposure

Infants

• neisseria meningitidis
• streptococcus pneumoniae
• haemophilia influenzae

Question 21

Mechanism of TI antigen –> protein conjugation

Examples

Answer 21

Will work if the B cells are specific 
B cells internalise antigen 
Expressed on surface 
Attracts SPECIFIC T CELLS
Strong antibody response 

Neisseria meningitidis
Streptococcus pneumoniae
Haemophilus influenzae

Question 22

Important changes to immunisation schedule

Answer 22

The addition of a pneumococcal conjugate vaccine (PCV) at 2, 4 and 13 months of age;

A dose of MenC vaccine at 3 and 4 months;

A booster dose of Hib and MenC vaccine (given as a combined Hib/MenC vaccine) at 12 months of age.

HPV vaccine for teenage girls

BCG no longer routinely given to teenagers. Targeted on at risk infants.