Principles of Immunisation

Question 1

What are the two main types of immunity?

Answer 1

adaptive - responsible for memory and specificity

innate- protective barriers which don’t change for e.g. mucosal layers that prevent infection

Question 2

What are the typical cells of adaptive immune system?

Answer 2

lymphocytes and the two important lymphocytes being t cells (drive antibody immune responses) and b cells (antibody producing cells)

Question 3

What are the two states of the adaptive immune system?

Answer 3

Active (natural and artificial forms of immunity) and passive (natural and artificial forms of immunity) (receive immunity but your immune system hasn’t had to do any work)

Question 4

What are the methods of passive immunity? (adaptive)

Answer 4

(Natural)
placental transfer of IgG
colostral transfer of IgA

(Artificial)
Immunoglobulin
therapy or
Immune cells

Question 5

What are the methods of active immunity? (adaptive)

Answer 5

(Natural)
infection or exposure

(artificial)
immunisation vaccines

Question 6

Differences between active and passive immunity?

Answer 6

ACTIVE
-you’re either infected or vaccinated
-develop antibody and t cell responses that will respond to every challenge with infection
-immune system specific for pathogen and drives memory immune response

PASSIVE
-test tube full of antibodies against a particular pathogen and administer to uninfected individual.
-Will help to prevention of disease
-immune system specific for pathogen
-no memory of infection from immune system
-doesn’t drive memory immune response

Question 7

Advantages and disadvantages of passive immunity?

Answer 7

Advantages:
Gives immediate protection

A quick fix

Disadvantages:
Short term effect – no immunological memory

Serum sickness – incoming antibody is recognised as a foreign antigen by the recipient and results in anaphylaxis

Graft versus host disease (cell grafts only) – incoming immune cells reject the recipient

Question 8

Why are maternal immunoglobulins transferred to the foetus or neonate naturally using a specialised mechanism involving the neonatal Fc receptor?

Answer 8

The neonatal Fc receptor transfers the antibody through cells and into the neonates bloodstream. This provides a certain amount of immunity to the baby for any recent pathogens.

Question 9

Give examples of passive immunity?

Answer 9

Snake or spider bites, scorpion or fish stings
- passive infusion of antibody specific for the toxin

Hypogammaglobulinaemia – primary or secondary
Infusion of g-globulins to reduce infection

Rabies Immunoglobulin -“Post-exposure prophylaxis”
together with vaccination

Question 10

Which are immunoglobulins for post exposure prophylaxis?

Answer 10

Human Normal Immunoglobulin (HNIG)
Hepatitis A
Measles
Polio
Rubella

Specific Immunoglobulins
Hepatitis B
Rabies
Tetanus
Varicella-Zoster Virus

Question 11

What is vaccination?

Answer 11

administration of antigenic material (a vaccine) to stimulate an individual’s immune system to develop adaptive immunity to a pathogen

Question 12

Describe killed whole organism vaccine?

Answer 12

Target organism, e.g., polio virus is killed

Effective and relatively easy to manufacture

Booster shots likely required

Virus must be heat killed effectively – any live virus can result in vaccine-related disease

Question 13

Describe attenuated whole organism?

Answer 13

An avirulent strain of target organism is isolated
Can be very powerful and better than killed
Simulate natural infection
Reversion back to virulent form
Refrigeration required

Question 14

Describe how you get a weaker form of the virus?

Answer 14

pathogenic virus is isolated from a patient and grown in human cultured cells

the cultured virus is used to infect monkey cells

the virus acquires many mutations that allow it to grow well in monkey cells

the virus no longer grows well in human cells (it is attenuated) and can be used as a vaccine

Question 15

Describe recombinant proteins as vaccines?

Answer 15

Generally, very safe
Easy to standardise
Not very immunogenic without an effective adjuvant
Need to understand how to generate immunity

Examples
Hepatitis B surface antigen (HBsAg)
Human papilloma virus (HPV) proteins

Question 16

Describe toxoid (modified toxin) vaccine?

Answer 16

Toxin is treated with formalin
Toxoid retains antigenicity but has no toxic activity
Only induces immunity against the toxin, not the organism that produces it
e.g. tetanus, diphtheria

Question 17

What are the contraindications of vaccination?

Answer 17

febrile illness- cannot be immunocompromised as immune system has to do a lot of the work

pregnancy- slightly immunocompromised

allergy- immunocompromised

Immunocompromised – cannot be given live attenuated vaccines as individuals may develop disease from the vaccine strain

Question 18

What is herd immunity’s purpose?

Answer 18

vaccine coverage of 90-95%

Vaccinated individuals are less likely to be a source of infection to others
Reduces the risk of unvaccinated individuals being exposed to infection
Individuals who cannot be vaccinated will still benefit from routine vaccination programmes

Question 19

What makes a good vaccine?

Answer 19

Potent antibody response – high antibody titers
Potent CD8+ cytotoxic T cell response
CD4+ T helper response
Memory

Question 20

Do we need t cell responses for vaccines?

Answer 20

If want vaccine to generate potent IgG response you need a T cell response as T cells act to optimise antibody production.
Drive b cells to make more effective antibody responses against pathogens.

Question 21

What are the challenges facing vaccines?

Answer 21

Conventional vaccines cannot elicit immunity against all infectious disease

Persistence – ideally vaccines should give life-long protection

Generation of memory cells

Protection of vulnerable groups
The very young, the elderly and immunocompromised individuals

Antigenic shift and drift, and strain diversity in general
Bird and swine influenza pandemics

The cold chain network

Question 22

Role of protein receptors, Hemagglutinin and neuramidase?

Answer 22

Genes encode two really important protein receptors hemagglutinin H and other neuramidase N (H1 and N1).
Hemagglutinin all about virus entering host cell and infecting cell and neuramidase all about exiting cell .

Question 23

Describe antigenic shift?

Answer 23

Influenza virus has eight separate RNA strands

Co-infection of a host with the virus allows genetic reassortments that give rise to novel antigenically distinct virus particles

Immune evasion and step increase in virulence
(body not able to deal effectively with flu strains)

e.g., the H1N1 influenza virus in 2009

Question 24

What is antigenic drift?

Answer 24

slight mutations in the human genome which give rise to slight differences in the receptors

Question 25

Describe the vulnerability of neonates?

Answer 25

not very good at mounting immune responses against particular types of pathogen, particularly polysaccharide coated pathogens.

Vulnerability <18–24 months to encapsulated bacteria such as pneumococcus, Hib and meningococcus

Fewer FDC, and B cells do not express costimulatory molecules

Short term antibody production

Question 26

Describe vulnerability of the elderly?

Answer 26

Reduced efficacy or responsiveness to vaccination
Oligoclonal responses lacking specificity
Reduced plasma cell survival niches (in bone)

Question 27

What is a B cell?

Answer 27

Something that is stimulated by a viral pathogen.
Will the undergo development such that it changes aspects of its cell phenotype and basically becomes an antibody producing factor.
Have b cell receptors on cell surface but change to becoming an antibody producing factory type cell - plasma cell. No longer has B cell receptor on surface but it secretes lots of antibody into the bloodstream.

Question 28

Describe the conjugate vaccine?

Answer 28

The antigen is the carbohydrate capsule (polysaccharide antigens)

Carbohydrates are poor antigens (do not stimulate the immune system as broadly as protein antigens), especially in babies

Conjugation of the carbohydrate to a protein carrier makes them more effective

Question 29

Describe checkpoint inhibitors?

Answer 29

New type of antibody immunotherapy used to treat a number of different cancers and they’re very powerful. Boost immune response against the cancer cells.
And can have vaccine effect - stop cancer relapsing.

Question 30

Describe personalised vaccines?

Answer 30

first test the individuals immunity against broad range of potential vaccines
take blood sample and incubate with panel
look to see which is generating certain amount of immunity