Vaccines and Vaccine Development Flashcards
What is passive immunisation?
The introduction of antibodies to an individual, meaning there is no immune response in the recipient (short-term).
What is active immunisation?
Recipient develops a protective adaptive immune response through the introduction of pathogen (vaccination).
Where are the antibodies for passive vaccines obtained from?
Hyper-immune donors (can either be human or animal)
What does VZV stand for, and what is it also known as?
Varicella-Zoster Virus
Also known as Chickenpox
Why is it important to know if a pregnant woman has had chickenpox before?
It is dangerous because it can cause foetal complications.
If mother shows VZV IgG in blood, then mother had it before and can be reassured.
What are the main aims of active immunisation?
Generation of an adaptive immune response without causing clinically-apparent infection
What is herd immunity?
When a sufficient number of a population has been vaccinated, making unimmunised individuals at low risk.
What type of antibody response do most vaccines generate?
IgG antibody response
What makes up vaccines?
- Antigens: stimulate antigen-specific T cell and B cell responses
- Adjuvants: Immune potentiators that increase the immunogenicity of a vaccine
- Excipients: Various diluents and additives that are required to maintain vaccine integrity
If a whole organism is used for an active vaccine, what must it be?
Live-attentuated or Inactive (killed)
In active vaccines consisting of subunits, what type of submits can be used?
- Toxoids: Chemically modified toxins from pathogens
- Capsular polysaccharides
- Conjugated polysaccharides
- Recombinant subunits
What are some examples of live-attenuated vaccines?
Measles
Mumps
Rubella
Cholera
Zoster
BCG
How are live-attenuated vaccines made?
1) Prolonged culture is placed in non-physioligcal conditions, which selects variants that are adapted to live in culture.
2) These variants are then no longer able to cause disease
What are the pros of live-attenuated vaccines?
- Replication occurs within the host, producing a highly effective and durable response
- In viral vaccines, infection leads to a good CD8 response
- Repeated boosts aren’t required
- Can sometimes lead to secondary protection unvaccinated individuals who get infected with the live-attenuated vaccine strain (e.g. polio)
What are the cons of live-attenuated vaccines?
Short shelf-life
May revert to wild type (rare)
Immunocompromised individuals may develop disease
What can a viral reactivation of zoster lead to?
Permanent infection to sensory ganglia, which can lead to long-term neuropathic pain
What is poliomyelitis?
Enterovirus that establishes infection in oropharynx and GI tract (alimentary phase)
Spreads to peyers patches (lymphoid tissue that line the small intestine) and then gets disseminated by lymphatics
In the viremia phase, haematogenous spread occurs
What phase do 1% of people with poliomyelitis develop?
Neurological phase
Replication occurs in motor neurons in spinal cord, brainstem and motor cortex - leading to denervation and flaccid paralysis
What happens during primary infection of TB?
1) Infection is established within phago-lysosomes of macrophages.
2) Macrophages then present TB antigens to TB-specific CD4 T cells, which secrete IFN-g that activates macrophages to encase TB in a granuloma
On a plain chest X-ray, how may TB present?
As calcified lesions
What is the only licensed TB vaccine?
BCG (Bacille Calmette-Guerin)
What are some examples of Killed/Inactive vaccines?
Hepatitis A
Influenza
What are the pros of inactive vaccines?
- No potential of reversion
- Safe for immunocompromised individuals
- Stable in storage
What are the cons of inactive vaccines?
- Mainly CD4 / antibody response
- Response is less durable than live-attenuated vaccines, meaning boosters will be required
- Higher uptake generally required in order to reach herd immunity
What is is used to determine whether an influenza virus is A, B or C?
Internal antigens of the virus (matrix and RNP (= ribonucleprotein)) which are type-specific
What are the external antigens of influenza virus?
Hemagglutinin and neuraminidase
What makes Streptococcus pneumoniae and Neisseria meningitidis resistant to phagocytosis?
Their thick polysaccharide coating. This is why vaccines against them consist of the purified polysaccharide coats (inducing IgG antibodies)
Which HPV subtypes can cause cervical cancer?
16 and 18
What are the pros of subunit vaccines?
- Safe
- Work well when primary infection may be prevented by an antibody response
- Can be used when culturing of virus is difficult
What are the cons of subunit vaccines?
- Development requires detailed knowledge of virology, pathogenesis and immunology
- Production is expensive
- Weaker immune responses so boosting is often needed
How do adjuvants boost the immune response to antigens?
Bind to PRRs on antigen presenting cells, leading to strong T cell and B cell response
