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M301 > W14 Vaccine types (GN) > Flashcards

W14 Vaccine types (GN) Flashcards

1
Q

What are the 3 Types of vaccination?

A
  • Whole organisms
    -Live attenuated vaccines
    -Killed/inactivated vaccines
  • Purified macromolecules (Partial microorganism)
    -Subunit/Recombinant Protein Vaccines
    -Toxoid Vaccines
    -Polysaccharidic or protein-conjugated Vaccines
  • Nucleic acid vaccines
    -DNA vaccines
    -mRNA vaccines
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2
Q

What is a Live attenuated vaccine?

A

Containing whole bacteria or viruses
which have been “weakened”(attenuated)
-Genetically altered microbes with reduced virulence but retain their immunogenicity
-Genes encoding virulence factors are deleted or mutated

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3
Q

What are the advantages? (4)

A

✓Follow a natural infection
✓Elicit a strong cellular and antibody response
✓Long-lasting response
✓One or two doses required

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4
Q

What are the disadvantages of a live attenuated vaccine?

A
  • Live microbes can mutate and revert back to a virulent form → causing mild disease (rare)
  • Attenuated forms can cause disease in immunocompromised patients and unborn babies
    -Contraindicated in immunocompromised or pregnant women
  • They require refrigeration to be active → heat and light can inactive the microbes
    -difficult to be shipped and stored in developing countries
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5
Q

Examples of live attenuated vaccines?

A

➢ measles, mumps and rubella (MMR), chickenpox, poliovirus, rotavirus,
nasal flu vaccines → Replicating viruses
➢ Bacillus Calmette Guérin (BCG) vaccine → Replicating bacteria
➢ Smallpox vaccine → Live non-replicating virus

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6
Q

What is a Killed/inactivated vaccine?

A

Inactivated microorganisms.
Containing whole bacteria or viruses which
have been killed/inactivated
-Microorganisms are grown in culture media and killed by heat or chemical agents (e.g. formalin)
* Microbes cannot replicate or cause disease, without comprising antigenicity

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7
Q

What are the advantages of a kill/inactivated vaccine? (2)

A

Advantages
✓Safer for immunodeficient patients and in pregnancy than live vaccines
✓More stable than live vaccines → no requirements of refrigeration
-can be shipped to developing countries as freeze-dried form

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8
Q

What are the disadvantages of a kill/inactivated vaccine?

A

Weaker response that live microorganisms →
multiple doses are required for long-term immunity
▪ A first dose primes the immune system, while boosters develop a protective immunity
▪ Adjuvants are CRITICAL for enhancing the response
▪ They may fail to develop immunity in
immunocompromised patients

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9
Q

What are examples of killed/inactivated vaccines?

A

➢ Polio, Hepatitis A, flu and rabies vaccines → viruses
➢ Pertussis, cholera, meningococcal vaccines → bacteria

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10
Q

Live attenuated versus inactivated vaccines

A

Production:
L- Cell culturing system under adverse conditions to select avirulent microorganisms.
Or genetical alteration
I- Culture and inactivation of microorganisms by chemicals/radiations

Booster requirement:
L- Usually, only a single booster
I- Multiple booster

Stability
L- Less stable
I- Stable

Immunity induced
L-Humoral and cell-mediated
I- Mainly humoral

Genetical reversion tendency:
L- May revert to virulent form
I- No risk

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11
Q

Subunit vaccines (microbial components)
What do they contain?
How are they produced?
Examples? (3)

A
  • Contain only antigenic molecules of microbes. Not the whole organism.
  • Produced by fractionating microbes into components or by recombinant DNA technology and purified
  • Components are selected as capable of stimulating a
    specific immune response and protect from relevant
    pathogen infection and/or related severe disease

Subunit vaccines (microbial components)
➢A) Protein/peptide vaccines
➢B) Toxoid
➢C) Polysaccharidic conjugates

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12
Q

What are the advantages of subunit vaccines?(microbial protein)

A

✓Safe for immunodeficient patients
✓Less likely to induce side effects

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13
Q

What are the disadvantages of subunit vaccines?(microbial protein)

A
  • Poor immunogenicity →Antigens may not retain their original 3-D conformation in the microbes
  • Require boosting doses
  • More challenging and expensive to develop
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14
Q

Subunit vaccines – A) Protein vaccines
What do they consist of?
Examples?

A
  • Consisting of protein/peptide antigen(s) including
    epitope(s) that antibodies or T cells recognise →
    triggering a specific strong immune response

➢ E.g. external viral proteins (envelope or capsid proteins)
* Can contain 1 to 20 antigens.

Hepatitis B vaccine, MenB Vaccine (Meningococcal B Vaccine)

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15
Q

Subunit vaccines – B) Toxoid vaccines
Examples?

A
  • Against bacteria producing exotoxins, responsible for a disease (C. tetani)
    -Soluble and heat-labile proteins released outside by viable bacteria (Gram +ve and -ve)
  • Toxoids are toxins produced in culture systems and detoxified to produce harmless vaccines that prime the immune system to inactivate the bacterial toxin

Diphtheria and tetanus vaccines → bacteria

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16
Q

Subunit vaccines – B) Toxoid vaccines
Advantages and disadvantages?

A

Advantages - Highly efficient and safe immunized agents (immunodeficient patients and in pregnancy) and no risk of mutations

Disadvantages - Require many boosters

17
Q

Subunit vaccines – C) Polysaccharidic conjugate
What are they produced against?

A

Produced against capsulated pathogenic bacteria
▪ S. pneumoniae (pneumococcus), N. meningitidis (meningococcus),

  • Include the surface polysaccharide (usually low
    immunogenic) on the capsule of pathogenic bacteria
  • Attached to a toxoid protein to creates a strong
    immune response → Conjugate
18
Q

Subunit vaccines – C) Polysaccharidic conjugate
Adv and Disadv?
Examples?

A

➢ Long-lasting immunity

➢Capsule polysaccharides are bacterial type-specific (require more polysaccharides to extend coverage to a bacterial species

✓ Hib/MenC vaccine (even alone) → Haemophilus influenzae type B capsular polysaccharide +
meningococcal capsule polysaccharide (group C) both directly conjugated to tetanus toxoid
✓ Children’s pneumococcal vaccine against Streptococcus pneumoniae → polysaccharides
from the surface of the 13 most common invasive bacterial types conjugated to tetanus toxoid

19
Q

Nucleic acid vaccines

A

Based on the principles of gene expression
* Design of antigen-coding DNA sequence (genetically engineered)
* Delivery inside human cells
* Exploiting the cellular machinery (transcription → translation) to produce viral proteins → antigens

20
Q

mRNA vaccines: Nucleic acid vaccines

A
  • Delivery of DNA vaccines inside cells
  • Delivery of mRNA vaccines inside cells
21
Q

A) mRNA vaccines
What are they based on?
MOA?

A

Based on synthetic RNA coding for microbial
antigenic protein (coronavirus spike proteins like
in the RNA vaccines against SARS-CoV-2 from
Pfizer and Moderna)

  • RNA enters cell cytoplasm (site of translation)
  • Translation produces coronavirus spike proteins
  • Spikes are presented outside the cell membrane
    to activate immune system
22
Q

B) DNA vaccines
What are they based on?
MOA?

A
  • DNA vaccines can be uptake by cells
  • A small portion (0.1%) reaches the nucleus
  • DNA is transcribed into mRNA and translated
    into antigenic proteins
  • Antigenic proteins are detected by the immune
    system → humoral and cell-based response

Plasmids including a gene encoding the microbial antigen
Vaccine antibody response to spike within 1 week

23
Q

Nucleic acid vaccines
What are the advantages? (3)

A

➢ Cheap and quick to make
➢ Cheap and quick to make
➢ Safe and effective to stimulate both humoral and cell-based immunity

24
Q

Nucleic acid vaccines
What are the disadvantages? (4)

A

➢ Low stability of mRNA vaccines, requiring low storage temperatures
➢ Individual variability (long-term effects)
➢ Intracellular delivery challenges
➢ Public hesitancy based on misconceptions

25
Q

Nucleic acid vaccines Examples? (2)

A

✓ Two COVID-19 mRNA Vaccines:
➢ Pfizer-BioNTech (Comirnaty) and Moderna vaccines, both based on the viral gene sequence encoding SARS-CoV-2 spike proteins (External envelope glycoproteins).

26
Q

Route of administrations for vaccines? (4)

A
  1. Intramuscular route (e.g. hepatitis B virus)
    * Administered into the muscle mass
    * Related to all vaccine containing adjuvant to minimise side effects
  2. Subcutaneous route (e.g. measles)
    * Into the subcutaneous layer between skin and muscle
  3. Intradermal route (e.g. BCG)
    * Into the dermal layer of the skin (BCG live vaccine to prevent neurovascular injury)
  4. Oral route (e.g. rotavirus)
    * Making injection easier to eliminate the need for needle
27
Q

Which statement about inactivated microbial vaccines is incorrect?
A) They can provide long-lasting immunity with a single dose
B) They do not replicate
C)They usually require booster doses
D)They are generally safe for immunocompromised patients
E) Chemicals can be used to inactivate infectivity

A

=A
(multiple booster required as opposed to live-attenuated where usually only a single booster is required)

M301 (78 decks)

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