vaccines lecture 1 Flashcards
what are the 2 major parts of immune system
- innate
- adaptive
what is the innate immune system
First line of defense
- Responds quickly to invaders
- Primed and ready to fight at all times
- No adaptation in response (same response on re-exposure)
- Acts to confine invader and stops spread
- No memory persists afterwards
what is the adaptive immune system
Second line of defense
- Slower response
- Adapts to invaders (faster and stronger response on re-exposure)
- Memory persists afterwards
The innate immune system has 3 main part what are they
- physical barriers
- chemical barriers
- cellular barriers
The adaptive immune system has 2 main part what are they
- B cells
- T cells
what are the types of immunity
- Passive
- active
what is passive immunity
- can be natural or artificial
- natural: Antibodies transmitted from mother to baby
- artificial: Antibodies acquired from a medicine
what is active immunity
- can be natural or artificial
- natural: Antibodies developed in response to an infection
- artificial: Antibodies developed in response to a vaccination
what is an antigen
Antigen = molecular structure which may be present on the outside surface of a pathogen that triggers response an immune.
What is an antibody
Antibody = proteins produced by B cells. They are specialised Y-shaped proteins that tag antigens for destruction
what is a vaccine
Vaccination = when a vaccine has been administered to you
what is immunisation
Immunisation = process of what happens in your body after you have received a vaccine
Give an example of a pathogen
SARS-CoV-2 ( Covid-19 )
Describe the structure of the SARS-CoV-2 ( Covid-19 ) pathogen
SPIKE PROTEINS
- The spike proteins are anchored into the viral envelope and form a crown like appearance. The spike proteins attach to the target cell and allow the virus to enter it
ENVELOPE
- The RNA is surrounded by an envelope which has different roles in the life cycle of the virus. These may include the assembly of the new virus and helping the new virus to leave the infected cell
RNA
- The RNA is inside the envelope and acts as a template so that once it is inside the host cell, the coronavirus can replicate itself and be released into the body
what is the R₀ value
- Term that describes how contagious/transmissible
an infection disease is - R0=Basic Reproduction Number
- Average number of secondary cases arising from a
primary infection case in an entirely susceptible population - R₀ < 1
- R₀ = 1
-R₀ >1
what is herd immunity
Refers to indirect protection of a community of people from a disease by immunising a critical proportion of that population
What is a vaccine?
- A vaccine is a biological preparation
- Typically contains weakened or inactive parts of a particular disease-causing pathogen
what do vaccines do
- Improves immunity to a particular disease
- Triggers an immune response within the body
- Relies on the generation of immunological memory
- Mimics a natural infection without causing illness to the individual
- Protects not only the vaccinated individual but also their community
how do vaccines work
Vaccination ‘programs’ the immune system to remember a particular disease pathogen by allowing it to ‘practice’ on a weakened or killed version of the pathogen. This is called primary response to a pathogen
If the pathogen invades the body again in full strength, the immune system is ready to respond quickly. This is called a secondary response to a pathogen. Secondary responses happen faster and at a greater magnitude than primary responses, resulting in the creation of more antibodies to fight the pathogen and more memory cells to fight it in the future
what do an ideal vaccine do
- Produce the same immune protection which usually follows natural infection but without causing disease
- Generate long lasting immunity
- Interrupt the spread of infection
what are the 3 main types of vaccines
- Whole pathogen vaccines
- Subunit vaccines
- Nucleic acid vaccines
- Viral vectored vaccines
Whole pathogen vaccines
Live attenuated
Inactivated
Subunit vaccines
Conjugate
Toxoid
Recombinant protein
Nucleic acid vaccines
RNA
Viral vectored vaccines
Viral vectored
Live attenuated vaccines
Obtained from live pathogenic organisms
Pathogenic organisms are treated to become attenuated (or weakened) – lose capacity to induce full-blown disease but retain immunogenicity
Pathogenic organism is attenuated by introducing it into a species in which it does not replicate well or forcing it to replicate repeatedly in tissue culture
Activates T-killer cells
advantages of Live attenuated vaccines
Most potent of all types of vaccines – mimic real infection
Produces a strong immune response
Typically produce long-term immunity after one or two doses
Limitations of Live attenuated vaccines
Potential to revert to virulent/infectious form
Poor stability – require strict control of storage and transport conditions
Should not be administered to immunocompromised patients (e.g. blood cancer patients, pregnant women, chemo/radiation therapy patients)
Examples of Live attenuated vaccines
Part of the routine immunisation schedule
Measles, Mumps and Rubella (MMR)
Rotavirus
Nasal Influenza
Shingles
Travel Vaccines
MMR
Bacillus Calmette-Guerin (BCG) – protection against tuberculosis
Oral Typhoid
Yellow Fever
Inactivated vaccines
Obtained through thermal of chemical inactivation of pathogenic agents
Pathogens remain immunogenic but can’t replicate within the host
advantages of Inactivated vaccines
Safer than live attenuated vaccines (low risk of reverting to the virulent, infected form)
Usually more stable than live attenuated vaccines – easier to store and transport
Limitations of Inactivated vaccines
Excessive inactivation treatment can destroy immunogenicity
Insufficient treatment can leave infectious agents present in the vaccine
Requires mandatory booster immunisations
Examples of inactivated vaccines
Part of the routine immunisation schedule
Polio
Injectable Influenza
Hepatitis A (specialist groups only)
Travel Vaccines
Cholera
Hepatitis A
Japanese Encephalitis
Polio
Rabies
Tick-borne Encephalitis
Injectable Typhoid
Subunit vaccines
One or more antigenic fragments of the pathogen (e.g. proteins, polysaccharides, capsid) are used to stimulate the immune response
Antigens may be obtained through recombinant protein expression, production in yeast cells or bacteria or extraction from infected cells
Generally require addition of an adjuvant
advantages of Subunit vaccines
Immune response can focus on antigenic fragment of the pathogen only
Safer than whole pathogen vaccines because do not contain whole pathogen
Usually more stable than whole pathogen vaccines – easier to transport and distribute
Can be given safely to immunocompromised patient
Limitations of Subunit vaccines
Highly complicated manufacturing process, requiring synthesis, isolation and purification steps to obtain the antigen
Less immunogenic than whole pathogen vaccines – requires booster immunisations
Local side effects (e.g. sore at injection site) more common with these types of vaccines
Conjugate vaccines
Made using the polysaccharides, or sugars, that form the outer coating of many bacteria
Part of the routine immunisation schedule
Haemophilus influenza type b (Hib)
Pneumococcal
Meningococcal ACWY
Travel Vaccines
Meningococcal ACWY
Toxoid vaccines
Made using inactivated version of bacteria releasing toxins
Elicit immune responses against disease-causing proteins, or toxins, secreted by the bacteria
Called ‘toxoids’ because they look like toxins but are not poisonous
Part of the routine immunisation schedule
Diphtheria
Tetanus
Pertussis
Travel Vaccines
Tetanus
Recombinant Protein vaccines
madeusingbacterial or yeast cells to manufacture the vaccine
Part of the routine immunisation schedule
Human papillomavirus (HPV)
Hepatitis B (specialist groups only)
Meningococcal (MenB)
Travel Vaccines
Hepatitis B
Nucleic acid vaccines
Unlike other vaccines, these vaccines do not supply the protein antigen to the body
Provide the genetic material (DNA or RNA) of specific antigens to develop immunity
Nucleic Acid Vaccines include: DNA and RNA Vaccines
advantages of Nucleic acid vaccines
Safer than whole pathogen vaccines because do not contain whole pathogen
Relatively easy to manufacture
Limitations of Nucleic acid vaccines
RNA vaccines requires ultra low storage
(< - 70°C)
Booster immunisations may be necessary
examples of Nucleic acid vaccines
RNA vaccines use messenger RNA (mRNA) inside a lipid (fat) membrane
RNA vaccines are not capable of combining with the human genetic code (DNA)
COVID-19
- BioNTech Pfizer
- Moderna
RNA vaccines
Messenger ribonucleic acid (mRNA) vaccine
Contains the genetic sequence (mRNA) for the spike protein, which is found on the surface of the SARS-CoV-2 virus, wrapped in a lipid envelope
When injected, the mRNA is taken up by the host’s cells, which translate the genetic information and produce the spike proteins
This stimulates the immune system to produce antibodies and activate T-cells
Viral vectored vaccines
Like nucleic acid vaccines, these vaccines do not supply the protein antigen to the body
Provide the genetic material (DNA or RNA) of the antigen to host cells using a safe virus
In turn, the cells produce the antigen which stimulates an immune response
Viral vectored vaccines include: Replicating and non-replicating vaccines
advantages of Viral vectored vaccines
Safer than whole pathogen vaccines because do not contain whole pathogen
Relatively easy to manufacture
Cheaper to produce than nucleic acid vaccines and subunit vaccines
Limitations of Viral vectored vaccines
Booster immunisations may be necessary
examples of Viral vectored vaccines
Non-replicating viral vectors do not retain the ability to make new viral particles during the process of delivering the vaccine antigen to the cell
COVID-19
- Oxford AstraZeneca
Viral vectored vaccines
Non-replicating viral vector vaccine
Uses part of a weakened adenovirus as a carrier to deliver the genetic sequence for the SARS-CoV-2 virus spike protein into cells
When injected, the modified adenovirus binds to the surface of human cells and delivers the genetic code (mRNA) for the spike protein
This stimulates the immune system to produce antibodies and activate T-cells
