Vaccines Flashcards by Gabor Szloboda

What are the three types of vaccines used?

Whole-killed, toxoid and live attenuated.

How well did you know this?

Not at all

Perfectly

Immunisation can be…

Passive immunisation

Active immunisation or Vaccination

How well did you know this?

Not at all

Perfectly

Define passive immunisation

The administration of pre-formed immunity from one person/animal to another person.

How well did you know this?

Not at all

Perfectly

What are the limitation of passive immunisation?

Only humoral (AB) mediated - not work if cell mediated.

How well did you know this?

Not at all

Perfectly

What are the advantages of passive immunisation?

Gives immediate protection.
Effective in immunocompromised patients.

How well did you know this?

Not at all

Perfectly

What are the disadvantages of passive immunisation?

Short-lived, possible transfer or pathogens - serum sickness:

How well did you know this?

Not at all

Perfectly

Example of passive immunisation

Specific immunoglobulin (Ig)
- Human Tetanus Ig (HTIG) rapid protection of exposed individuals.

Human Rabies Specific Ig - Used after exposure to rabies to give protection until vaccine becomes effective.
Human Hepatitis B Ig (HBIG)
Varicella Zoster Ig (VZIG)

How well did you know this?

Not at all

Perfectly

Human Normal Immunoglobulin (HNIG) (Passive immunisation)

Prepared from pools of at least 1000 donors, contains ABs against measles, mumps, varicella, hep a etc…

How well did you know this?

Not at all

Perfectly

Convalescing serum (SARS Co-V2)

Pooled from people recovering from COVID-19 but clinical trial result suggests no overall increased efficacy against virus using passive immunisation.

How well did you know this?

Not at all

Perfectly

Active immunisation

Non-living vaccines (whole killed and toxoids)

Live attenuated vaccines

How well did you know this?

Not at all

Perfectly

The whole microbe vaccine

Bacteria or viruses grown in vitro and inactivated (formaldehyde or B-propionolactone)

Non-living vaccines do not cause infection - AG induced response that protects against infection - by non-self AG recognition.

Can also be cell-free toxoids - inactivated toxins.

How well did you know this?

Not at all

Perfectly

Problems and limitations of whole killed vaccine

Organism must be grown to high titre in vitro (some cannot be grown in labs).

Whole pathogen can cause excessive reactogenicity (ADR)

Immune response are not always close to the normal response to infection.

Requires two shots.

How well did you know this?

Not at all

Perfectly

Examples of bacterial whole killed vaccines

Diphtheria - toxoid (treated with formaldehyde)

Tetanus - toxoid

Pertussis - killed whole bacteria. Now acellular pertusses in the UK.

DTP given as one.

Cholera - heat killed bacteria.

How well did you know this?

Not at all

Perfectly

Examples of viral whole killed vaccines.

Polio
Influenza vaccine
Hep A
Rabies
SARS-Co-V2

All inactivated viruses.

How well did you know this?

Not at all

Perfectly

Live attenuated vaccines

Organism replicate within the host and induce an immune response which is protective against the wild type but does not cause disease.

More real life and provides better protection.

How well did you know this?

Not at all

Perfectly

Attenuations

Cultured in such way that is does not cause disease when inoculated into humans.

Pathogenicity lost
Antigenicity retained

How well did you know this?

Not at all

Perfectly

What are the advantages of live attenuated vaccines?

Immune response more closely mimics real infection - not fixed, no shape change.

Better immune response - lower doses.

Route of administration may be favourable (oral).

Fewer doses may be required.

How well did you know this?

Not at all

Perfectly

What are the problems and limitations with live attenuated vaccines?

Impossible to balance attenuation and immunogenicity.

Reversion to virulence.

Transmissibility.

May not be attenuated enough for immunocompromised people.

How well did you know this?

Not at all

Perfectly

Examples of bacterial live attenuated vaccines (ONLY 2)

BCG - TB
Salmonella typhi - temp. sensitive. Orally given.

Examples of viral live attenuated vaccines

Poliomyelitis (Sabin) - eradicate polio

Vaccinia virus - smallpox: cross reaction between itself and the variola virus.

MMR

Why are so many pathogens lack a vaccine?

Pathogen too difficult to grow

Killed pathogen not protective (shape change)

Impossible to obtain attenuated and suitably immunogenic strain

Too many strains causing disease etc.

List the novel vaccine approaches

Recombinant Proteins
Synthetic Peptides
Live Attenuated Vectors
mRNA Vaccines
Polysaccharide-Protein Conjugates

Recombinant proteins

Genetically engineered - from bac, yeast, insect or mammalian cells.

Don’t have to grow pathogens in vitro.

Major issue: finding the proteins that are protective and strong enough to generate an immune response.

Examples:
HepB surface AG
HPV Cervarix, Gardasil
SARS-Co-V2 Novovax

Synthetic peptides

Directly uses a machine (no need to grow pathogens)

Problems:
Identifying protective epitopes
Inducing a strong + broad response

Viral vectors

Composed of safe living attenuated viruses that have inserted genes encoding foreign AGs which are displayed to the immune system. Covid jab.

How do viral vectors work?

When injected the virus is taken up by an APC, the viral DNA is released and enters the nucleus. The viral DNA is transcribed to mRNA and translated to a protein – some of this spike protein is presented with MHC II on the cell surface as a foreign antigen. This is recognised by T-cells and initiates an immune response to the spike protein. The virus is replication deficient and can not replicate in human cells limiting its spread.

DNA vaccines

Mammalian plasmid containing DNA that encodes for the foreign protein of interest is injected directly. Required a lipid nanocarrier to get DNA into human cell.

What are the advantages and disadvantages of DNA vaccines?

Adv: no need to grow pathogen or viral vector. No live organism is involved DNA is cheap to produce Disadv: poor immunogenicity None on the market

mRNA vaccines

mRNA of the target foreign protein is synthesized in vitro + lipid nanoparticle (protects from degradation) crosses plasma membrane. Translated in cytoplasm and the protein is presented on MHC.

T-independent AGs

Bacterial capsular polysaccharides cannot be processed and presented on MHC class II No T cell help Antibody response of low magnitude Low affinity Predominantly IgM Little or no boosting on secondary exposure Infants respond especially poorly and are major target group for these vaccines Haemophilus influenzae (conjugate vaccines - type B polysaccharide vaccine or 7-valent conjugate. Neisseria meningitidis type C - polysaccharide-protein conjugate. Streptococcus pneumoniae 23-valent polysaccharide vaccine or 7-valent conjugate.

At what ages is pneumococcal conjugate vaccine is given?

PCV at 2, 4, 13 months

Meningitis C is given at

3 and 4 months

Booster dose of Hib and MenC vaccine (combined) given at

12 months of age.

HPV vaccine for...

Teenage girls and boys...

BCG vaccine changes

No longer given routinely - targeted risk infants.

8 weeks old vaccinations

Diphtheria Tetanus Pertussis Polio Hib HepB MenB Rotavirus (Oral)

12 weeks vaccinations

Diphtheria Tetanus Pertussis Polio Hib HepB Rotavirus Pneumococcal conjugate vaccine PCV13

16 weeks vaccinations

DTP Polio Hib HepB MenB

One year old

Hib/MenC Pneumococcal conjugate vaccine MenB MMR

Eligible paediatric age groups

Live attenuated influenza vaccine (nasal spray, single application in each nostril)

3 years and 4 months

Diphtheria Tetanus Pertussis Polio MMR

12 to 13 years old

HPV

14 years old

Tetanus Diphtheria Polio Meningococcal ACWY conjugate

65 years old

Pneumococcal polysaccharide vaccine

65 years old and older

Inactivated influenza vaccine

70 years old

Shingles vaccine