Vaccine Delivery

Question 1

What is a conventional prophylactic vaccine?

Answer 1

Induction of immunity to a pathogen by injection of a weaken, modified or related form of the pathogen which is no longer pathogenic

Also results in B-cell memory

Question 2

What are the active ingredients in traditional vaccines?

Answer 2

1. Killed organisms or their components
2. Attenuated organisms (different organism, culture condition, selection of non-virulent variants)

Question 3

What are the types of active ingredients in biotechnology-based vaccines?

Answer 3

• Organisms with specific mutations or deletions
• Recombinant protein vaccines
• Recombinant DNA
• Messenger RNA
• Synthetic peptides (used with same epitopes and antigens from the target)
• Plant vaccines (used to stimulate immune system)

Question 4

What are some future generation vaccine types?

Answer 4

• Therapeutic vaccines
• Tolerogenic vaccines

Question 5

What is a therapeutic vaccine?

Answer 5

These vaccines are designed to stimulate an immune response in patients who are already infected and has already mounted an immune response to that organism

ex. Cancer, viral diseases, Alzheimer’s disease

Question 6

What is a tolerogenic vaccine?

Answer 6

These vaccines hope to “calm” the immune system response to self-antigens often targeted in autoimmune diseases or transplanted organs

Question 7

What are the primary lymphoid organs?

Answer 7

• Bone marrow: B cell maturation
• Thymus: T cell maturation

Question 8

What are the functions of the primary lymphoid organs?

Answer 8

Provide a site for lymphocytes (B and T cells) to develop from a lymphoid stem cell

Question 9

What are the secondary lymphoid organs?

Answer 9

• Lymph nodes
• Spleen
• Mucosal lymphoid tissues (lung, gut)

Question 10

What are the functions of the secondary lymphoid organs?

Answer 10

They are sites where lymphocytes are most active (meeting places for antigens and the immune system)

Question 11

Briefly explain lymphocyte activation?

Answer 11

1. Antigen presentation (APC to T helper cell)
2. T helper clonal expansion and maturation (with cytokines released by dendritic cells)
3. T helper cells help B cell (humoural immunity) and Cytotoxic T cell (cellular immunity) activation

Question 12

What is the utility of adjuvants in vaccines?

Answer 12

Antigens alone do not induce a productive immune response

Adjuvants:
- Awaken the adaptive immune system
- Activate antigen presenting cells
- Initiate cytokine secretion

100x the effect for the same amount of antigen, plus reduce risk of actually causing disease because antigen numbers are lower

Question 13

How do dendritic cells differentiate between non-self and self?

Answer 13

Pathogen-Associated Molecular Patterns (PAMPs) are recognized by dendritic cells on non-self

These non-self molecules are perceived by dendritic cells as molecular signatures of infection

Question 14

What are the advantages of adjuvant in vaccine formulations?

Answer 14

1. Enhance immunogenicity of weak antigens
2. Reduce amount of antigen or frequency of immunizatons to acheive immunity
3. Improve the efficacy of vaccines

Question 15

What is the purpose of a vaccine delivery system?

Answer 15

They facillitate transport of antigen to target site

Question 16

What are some ideal qualities for drug delivery systems?

Answer 16

• Can target dendritic cells
• Can be coupled to dendritic cell maturation agents
• Can accommodate any type of antigen
• Permits intracellular targeting (ability to be phagocytosized)
• Synthetic, stabe, available for global use

Question 17

What are the advantages of PAMP (TLR ligand) as a vaccine delivery device?

Answer 17

APC binds to PAMP and leads to internalization

The PAMP-antigen allows for improved internalization of antigen and confers protective immunity

Question 18

What are some types of preventative cancer vaccines?

Answer 18

HPV vaccines (ex. Gardasil, prevention of genital and head cancers)

Hepatitis B vaccine (prevention of liver cancer)

Question 19

What are some types of therapeutic cancer vaccines?

Answer 19

• Bacillus Calmette-Guerin (BCG) is approved for early-stage bladder cancer
• Sipuleucel T (vaccine composed of patients own stimulated dendritic for prostate cancer)

Question 20

How does the Stimuvax vaccine work?

Answer 20

It is a liposomal MUC1 (overexpressed in adenocarcinoma cells) cancer vaccine

The MUC1 antigen is inside a liposome system and injected into patient

The antigen enters APC and stimulates formation of specific B and T cells

These MUC1 specific lymphocytes eliminate MUC1+ tumour cells

Question 21

How were the Pfizer and Moderna COVID-19 vaccines different from the other types?

Answer 21

They were RNA-based vaccines (instructions for spike protein is injected into patients)