Principles of Immunisation Flashcards
Types opf immunity
- adaptive= active (immunisation vaccines, infection or
exposure) - innate= passive: recieved immunity (placental transfer of IgG, colostral transfer of IgA, immunoglobulin
therapy or immune cells)
Passive immunity
- short term immunity using antibodies produced outside the body
- specificity
- no memory
Active immunity
- the immunity that results from the production of antibodies by the immune system in response to the presence of an antigen
- specificity
- memory
Advantages of passive immunity
- Gives immediate protection
- A quick fix
Disadvantages of passive immunity
- 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
Give natural and artificial examples of passive immunity
Natural: maternal immunoglobulins transferred to foetus or neonate naturally using a specialised mechanism involving the neonatal Fc receptor
Artificial:
* Snake bite - passive infusion of antibody specific for the toxin
* Hypogammaglobulinaemia (1/2ndry indsion of gamma-globulins to reduce infection
* Rabies immunoglobulin - “post-exposure prophylaxis” together with vaccination
Examples of natural and artificial, active immunity
- natural= exposure/infection
- artificial= vaccination
Advantages of active immunity
- Antigen (whole organism or part of it) stimulates immune response
- (often) Long term immunity - may be lifelong
- Immunological memory
- No immediate effect, but faster and better response to next antigenic encounter
Vaccination
administration of antigenic material (a vaccine) to stimulate an individual’s immune system to develop adaptive immunity to a pathogen
common diseases vaccinated against
probs don’t need to know
measles, mumps, rubella, polio, diptheria, tetanus, cholera, typhoid, yellow fever, HPV, shingles, hep A
Explain vaccines which kill the whole organism
- arget organism, e.g., polio virus is killedT
- 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
Explain vaccines that attenuate the whole organism
- 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
Give the mechanism of attenuation
- pathogenic virus is isolated from a patient and grown in human cultured cells
- cultured virus used to infect monkey cells
- 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
Types of vaccine
4 types
- Live attenuated (LAV)
- Inactivated (killed antigen)
- Toxoid (inactivated toxins)
- Subunit (purified antigen)
How does the subunit vaccine work
- Recombinant proteins
- Generally very safe
- Easy to standardise
- Not very immunogenic without an effective adjuvant
- Need to understand how to generate immunity
How does the toxoid vaccine work
- 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
- Can’t proliferate in environment???
ex inc: tetanus, diphtheria
Diseases LAV used for
*Tuberculosis (BCG)
*Oral polio vaccine (OPV)
*Measles
*Rotavirus
*Yellow fever
Diseases inactivated vaccines used for
*Whole-cell pertussis (wP)
*Inactivated polio virus (IPV)
what diseases are toxoid vaccines used for
*Tetanus Toxoid (TT)
*Diphtheria toxoid
Diseases subunit vaccines used for
*Acellular pertussis (aP)
*Haemophilus influenzae type B (Hib)
*Pneumococcal (PCV-7, PCV-10, PCV-13)
*Hepatitis B (hepB)
Vaccine schedule for children
- 2 months old= Diphtheria, tetanus, pertussis, polio, Haemophilis influenzae type b, Streptococcus pneumoniae, rotavirus
- 3 months old= Diphtheria, tetanus, pertussis, polio, Haemophilis influenzae type b, Neisseria meningitidis C, rotavirus
- 4 months old= Diphtheria, tetanus, pertussis, polio, Haemophilis influenzae type b, Streptococcus pneumoniae
- 12-13 months old= Haemophilis influenzae type b, Neisseria meningitidis C, measles, mumps, rubella, Streptococcus pneumoniae
- 2/3/4 years old= Influenza
- > 3 years 4 months old= Diphtheria, tetanus, pertussis, polio, measles, mumps, rubella
- 12-13 years old= Human papilloma virus (females only)
- 13-18 years old= Diphtheria, tetanus, polio, Neisseria meningitidis C
vaccines for travellers
- Hepatitis A
- Typhoid
- Neisseria meningitidis serogroups A, C, W135, Y
- Cholera
- Yellow fever
- Japanese encephalitis
- Tick-borne encephalitis
- Rabies
Contraindications of vaccination
reason for someone not to recieve treatment (harmful)
Temporary:
* Febrile illness
* pregnancy - cannot be given live attenuated vaccines
Permanent:
* allergy
* immunocompromised - cannot be given live attenuated vaccines as individuals may develop disease from the vaccine strain
Explain herd immunity
- Primary aim (of vaccination) is to protect individual who recieves the vaccination
- Vaccinated person less likely to be source of infection to others
- Dec risk of unvaccinated individual being exposed
- Individuals who can’t be vaccinated still benifit
What vaccine coverage levels (ish) would lead to herd immunity
90-95%
What makes a good vaccine
- Potent antibody response - high antibody titers
- Potent CD8+ cytotoxic T cell response
- CD4+ T helper response
- Memory
Challeneges to vaccines
- Conventional vaccines cannot elicit immunity against all infectious disease
- Persistance - don’t always give lifelong protection
- Generation of memory cells
- Antigenic shift/drift an strain diversity
- Cold chain netwok (how get them to where they need to go)
Antigenic shift
1.Influenza virus has eight separate RNA strands
2.Co-infection of a host with the virus allows genetic reassortments that give rise to novel antigenically distinct virus particles
3.Immune evasion and step increase in virulence
What does antigenic drift arise from
point mutations
cold chain network
Maintain product quality from time of manufacture until point of administration by ensuring vaccines are stored and transported within reccomemded temp ranges
vulnerability of neonates
- 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
vulnerability of elderly
- Reduced efficacy or responsiveness to vaccination
- Oligoclonal responses lacking specificity
- Reduced plasma cell survival niches
Explain conjugate vaccines
- The antigen is the carb capsule (polysacharride)
- Carbs are poor antigens (don’t stimulate the immune system as broadly as protein antiges), especially in babaies
- Conjugation of the carb to a protein carrier makes them more effective
checkpoint inhibitors
*Checkpoint inhibitor antibodies unlock the gateway to the adaptive immune system
*Powerful anti-tumour responses
*But potential for immune related adverse effects
Boost immune response against cance cells
how does an immune response occur following vaccination
(brief)
Vaccination increases the levels of circulating antibodies against a certain antigen.
