Immuno + microbio - vaccines + immune BOOSTER drugs

Question 1

R0 = ?

Answer 1

R0 = the average no. of people 1 sick person will infect

Question 2

To eliminate a disease with a vaccine, what are the requisites of success?

Answer 2

1. vaccine must induce lasting effective immune response
2. Pathogen has no animal reservoir
3. Pathogen must have only 1/ small number of strains
4. No latent reservoir
5. High coverage required for very contagious pathogens

Question 3

Describe herd immunity

Answer 3

Form of immunity that occurs when vaccination of a significant proportion of a population provides a measure of protection for individuals that are not immune.

Question 4

What is the herd immunity threshold?

Answer 4

% of fully immune required to stop spread of disease
= 1 - 1/R0

Question 5

Describe the primary immune response to a pathogen in a vaccine

Answer 5

1. Macrophages + DCs recognise pathogen PAMPs + DAMPs
2. Phagocytosis + Ag processing
3. Processed Ag is presented by APCs + recognised by naive T cells –> activate, proliferate + differentiate –> T-helper cells or Cytotoxic T cells
4. T helpers activate B cells which mature to plasma cells
5. Plasma cells produce antibodies specific for the antigen: neutralisation of infectivity OR Ab-dependent cellular cytotoxicity
6. If attenuated virus vaccine: Cytotoxic T cells kill infected cells

Question 6

What is the goal of vaccination?

Answer 6

Produce memory cells to the vaccine antigen
Post vaccination:
Entry of pathogen activated memory T cells which encourage immune response
Memory B cells become active plasma cells (more abs produced at a faster rate)
Memory killer T cell response may be reactivated

Question 7

Why is T cell memory response so great compared to the primary immune response?

Answer 7

Continue to PROLIFERATE IN ABSENCE OF AG
Express cell surface proteins to allow them to migrate to NON-LYMPHOID TISSUES
EASILY ACTIVATED compared to naiive T cells

Question 8

Why is B cell memory response so great compared to the primary immune response?

Answer 8

Long LIFE SPAN
More EASILY ACTIVATED
High levels of PRE-FORMED IgG antibody exist –> therefore quicker response

Question 9

4 features of a perfect vaccine

Answer 9

Easy storage
Good protection
Single injection
No adverse effects

Question 10

What are inactivated vaccines? Give 3 examples

Answer 10

Whole microorganism destroyed by heat/ chemicals/ radiation/ Abx- no longer causes disease
Influenza
Cholera
Polio

Question 11

Give 3 advantages and 4 disadvantages of inactivated vaccines

Answer 11

+ Stable
+ Constituents clearly defined
+ Unable to cause infection

• Need several doses
• Local reactions common
• Adjuvant needed
• Shorter lasting immunity

Question 12

What are attenuated vaccines? Give 4 examples

Answer 12

Live organisms modified to be less virulent
Measles
Mumps
Rubella
Yellow fever

Question 13

Give 3 advantages and 3 disadvantages of attenuated vaccines

Answer 13

+ Single dose often sufficient to induce long lasting immunity
+ Stimulates response to multiple protective antigens
+ Strong immune response evoked

• Potential to revert to virulence: CI in IS
• Can cause illness directly
• Poor stability

Question 14

What are Toxoid vaccines? Give 2 examples

Answer 14

Inactivated toxic component
Tetanus
Diphtheria

Question 15

What are subunit vaccines? Give 2 examples

Answer 15

Protein component of the microorganisms/ synthetic virus-like particles
Lack viral genetic material + unable to replicate
Hepatitis B
HPV

Question 16

What are conjugate vaccines? Give an example

Answer 16

Poorly immunogenic antigens paired with a protein that is highly immunogenic (adjuvant)
Haemophilus Influenzae type B

Question 17

What are Heterotypic vaccines? Give an example

Answer 17

Pathogens that infect other animals but do not cause disease/ mild disease in humans
Jenner’s use of cowpox to protect against smallpox.

Question 18

What are viral vector vaccines? Give 2 examples

Answer 18

Use a modified virus (e.g adenovirus) to deliver genetic code for an antigen
Ebola
AZ COVID vaccine

Question 19

What are nucleic acid vaccines? Give 2 examples

Answer 19

Use DNA/ RNA from the pathogen
Immune cells produce spike protein from mRNA + display on cell surface, stimulating immune response
Pfizer + Moderna COVID

Question 20

What is the difference between monovalent and multivalent?

Answer 20

Mono: One specific strain covered
Multi: lots of strains covered

Question 21

Which one of the following viruses is the most contagious?
Ebola
Hep C
HIV
SARS
Measles

Answer 21

Measles

Question 22

which 2 vaccines must NOT be given to HIV +ve patients

Answer 22

BCG
Yellow fever

Question 23

Define an adjuvant

Answer 23

Enhance the immune response without altering its specificity

• mimics PAMP activity on TLRs

Question 24

Which adjuvant is most commonly used in vaccination of humans? How does it work?

Answer 24

Aluminium

• Bound to antigen + thus ensures a ‘slow steady stream’ of antigen.
• Helps to prime naive B cells

Question 25

Contraindications to live vaccines

Answer 25

• Immunocompromised patients
• Pregnancy
• Allergy to egg products
• Previous confirmed anaphylaxis