Vaccines and Vaccine Development

Question 1

What is passive immunisation?

Answer 1

The introduction of antibodies to an individual, meaning there is no immune response in the recipient (short-term).

Question 2

What is active immunisation?

Answer 2

Recipient develops a protective adaptive immune response through the introduction of pathogen (vaccination).

Question 3

Where are the antibodies for passive vaccines obtained from?

Answer 3

Hyper-immune donors (can either be human or animal)

Question 4

What does VZV stand for, and what is it also known as?

Answer 4

Varicella-Zoster Virus

Also known as Chickenpox

Question 5

Why is it important to know if a pregnant woman has had chickenpox before?

Answer 5

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.

Question 6

What are the main aims of active immunisation?

Answer 6

Generation of an adaptive immune response without causing clinically-apparent infection

Question 7

What is herd immunity?

Answer 7

When a sufficient number of a population has been vaccinated, making unimmunised individuals at low risk.

Question 8

What type of antibody response do most vaccines generate?

Answer 8

IgG antibody response

Question 9

What makes up vaccines?

Answer 9

• 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

Question 10

If a whole organism is used for an active vaccine, what must it be?

Answer 10

Live-attentuated or Inactive (killed)

Question 11

In active vaccines consisting of subunits, what type of submits can be used?

Answer 11

• Toxoids: Chemically modified toxins from pathogens
• Capsular polysaccharides
• Conjugated polysaccharides
• Recombinant subunits

Question 12

What are some examples of live-attenuated vaccines?

Answer 12

Measles

Mumps

Rubella

Cholera

Zoster

BCG

Question 13

How are live-attenuated vaccines made?

Answer 13

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

Question 14

What are the pros of live-attenuated vaccines?

Answer 14

• 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)

Question 15

What are the cons of live-attenuated vaccines?

Answer 15

Short shelf-life

May revert to wild type (rare)

Immunocompromised individuals may develop disease

Question 16

What can a viral reactivation of zoster lead to?

Answer 16

Permanent infection to sensory ganglia, which can lead to long-term neuropathic pain

Question 17

What is poliomyelitis?

Answer 17

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

Question 18

What phase do 1% of people with poliomyelitis develop?

Answer 18

Neurological phase

Replication occurs in motor neurons in spinal cord, brainstem and motor cortex - leading to denervation and flaccid paralysis

Question 19

What happens during primary infection of TB?

Answer 19

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

Question 20

On a plain chest X-ray, how may TB present?

Answer 20

As calcified lesions

Question 21

What is the only licensed TB vaccine?

Answer 21

BCG (Bacille Calmette-Guerin)

Question 22

What are some examples of Killed/Inactive vaccines?

Answer 22

Hepatitis A

Influenza

Question 23

What are the pros of inactive vaccines?

Answer 23

• No potential of reversion
• Safe for immunocompromised individuals
• Stable in storage

Question 24

What are the cons of inactive vaccines?

Answer 24

• 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

Question 25

What is is used to determine whether an influenza virus is A, B or C?

Answer 25

Internal antigens of the virus (matrix and RNP (= ribonucleprotein)) which are type-specific

Question 26

What are the external antigens of influenza virus?

Answer 26

Hemagglutinin and neuraminidase

Question 27

What makes Streptococcus pneumoniae and Neisseria meningitidis resistant to phagocytosis?

Answer 27

Their thick polysaccharide coating. This is why vaccines against them consist of the purified polysaccharide coats (inducing IgG antibodies)

Question 28

Which HPV subtypes can cause cervical cancer?

Answer 28

16 and 18

Question 29

What are the pros of subunit vaccines?

Answer 29

• Safe
• Work well when primary infection may be prevented by an antibody response
• Can be used when culturing of virus is difficult

Question 30

What are the cons of subunit vaccines?

Answer 30

• Development requires detailed knowledge of virology, pathogenesis and immunology
• Production is expensive
• Weaker immune responses so boosting is often needed

Question 31

How do adjuvants boost the immune response to antigens?

Answer 31

Bind to PRRs on antigen presenting cells, leading to strong T cell and B cell response