Semester 2: Vaccines and Vaccine Immunology

Question 1

What is immunization?

Answer 1

The process of producing a long-term, adaptive immunological response to a pathogen

Question 2

What are the conditions that a vaccine should fulfill.

Answer 2

Prevent the establishment and spread of a given infection
Produce antibodies against one or more epitopes of the pathogen
Provide lifelong protection (memory response)
Be immunogenic against the desired antigen
Be safe

Question 3

What is passive immunity with regards to vaccine?

Answer 3

The transfer of active immune mediators to a host
Typically antibodies
Maternal transfer
Artificial transfer
Provides protection against antigen
Does not provide memory

Question 4

What is active immunity with regards to vaccines?

Answer 4

The production of active immune mediators within a host
Innate adaptive (humoral and cellular)
Provides protection against antigen
Provides immune memory

Question 5

What is innate immunity?

Answer 5

Antigen non-specific
Involves recognition of PAMPs and DAMPs
Produces antimicrobial cytokines/chemokines, leads to inflammation, complement activation and clearing
Provides limited immunological memory

Question 6

What is adaptive immunity?

Answer 6

Antigen-specific
involves recognition of antigenic peptides following antigen presentation by APCs
Produces a cellular response (T cell, cytotoxic)
Humoral response (B-cell, antibody)
Immunological memory and sterilizing immunity

Question 7

When was the first vaccine administered?

Answer 7

1796 to a 6 year old boy for smallpox, inoculated with scrapings of cowpox lesions

Question 8

What characteristics does an ideal vaccine have?

Answer 8

Produces a lifelong memory response to infection that is sufficient to prevent disease following subsequent exposure to a given pathogen

Question 9

Which immune processes should be taking place when a person is vaccinated?

Answer 9

Both innate and adaptive

Innate influences the nature of the adaptive response

Question 10

Which immune response is crucial to efficacy?

Answer 10

Adaptive response

Question 11

What are the four vaccine types?

Answer 11

Live attenuated
Killed/inactivated
Subunit
Toxoids

Question 12

What are live attenuated vaccines?

Answer 12

Live/viable whole bacteria, virus etc
Often replication-deficient
May be strains of pathogen that do not cause disease in host (smallpox vaccine)
Grown in vitro

Question 13

What are the advantages of live attenuated vaccines?

Answer 13

Highly immunogenic
Best mimics exposure to the pathogen
Induces a response against multiple components of the pathogen

Question 14

What are the disadvantages of live attenuated vaccines?

Answer 14

Highly immunogenic
May cause mild illness
Difficult to develop against highly mutagenic pathogens

Question 15

What are killed/inactivated vaccines?

Answer 15

Non-living/non-viable whole bacteria, virus etc
Do not replicate, do not elicit de novo bacterial/viral gene expression
Inactivation by heat, irradiation, chemical inactivation

Question 16

What are the advantages of killed/inactivated vaccines?

Answer 16

Vaccine components cannot replicate

Contains multiple epitopes/antigens

Question 17

What are the disadvantages of killed/inactivated vaccines?

Answer 17

Relatively less immunogenic than live attenuated vaccines
May cause mild illness
Chemical inactivation compounds may elicit adverse reactions (Formaldehyde)

Question 18

What are subunit vaccines?

Answer 18

Contain one or more components of a pathogen
Do not replicate, do not elicit de novo bacterial/viral gene expression
May be delivered in a recombination vector

Question 19

What are the advantages to subunit vaccines?

Answer 19

Vaccine components do not replicate

Higher safety profile

Question 20

What are the disadvantages to subunit vaccines?

Answer 20

Relatively less immunogenic than live attenuated or inactivated vaccines
Contains limited epitopes/antigens
Does not effectively mimic the natural exposure of the host to pathogen

Question 21

What are toxoid vaccines?

Answer 21

Contains a modified or inactivated toxic component of a pathogen
I.e. diptheria toxoid, tetanus toxoid
Does not replicate, is not toxic, elicits immune response against bacterial/viral ect. toxin

Question 22

What are the advantages to toxoid vaccines?

Answer 22

Vaccine components cannot replicate

Higher safety profile?

Question 23

What are the disadvantages to toxoid vaccines?

Answer 23

Relatively less immunogenic than live attenuated or inactivated vaccines
Contains limited epitopes/antigens
Does not effectively mimic the natural exposure of the host to pathogen

Question 24

Why are vaccines recommended to immunocompromised patients?

Answer 24

To reduce risk of complication in response to exposure to disease

Question 25

What vaccines are CI’d in severely immunocompromised patients?

Answer 25

Live vaccines

Question 26

What vaccine components may elicit allergic reactions?

Answer 26

Formaldehyde

Egg albumin

Question 27

What vaccines are CI’d in pregnant patients?

Answer 27

Live vaccines

Question 28

What would cause you consider the possibility of neurological complications in response to a vaccine?

Answer 28

History of Guillian-Barre syndrome (autoimmune) in response to vaccine

Question 29

What vaccines are grown in chick embryos and therefore may contain egg albumin?

Answer 29

Influenza virus
Measles, mumps, rubella (MMR)
Rabies virus
Yellow fever virus

Question 30

What preservatives are added to vaccines?

Answer 30

Formaldehyde
Thimersoal (mercury)
Antibiotics

Question 31

Why are adjuvants/immunogens added to vaccines? What substances are added?

Answer 31

added to vaccines to instigate or potentiate an immune response to the vaccine epitopes
Alum, aluminum
Squalene

Question 32

What is squalene?

Answer 32

An organic component (cholesterol precursor) produced by all plants and animals, including humans.
Higher levels of anti-squalene antibodies found in patients suffering from gulf war syndrome

Question 33

What is gulf war syndrome?

Answer 33

Spectrum of acute and chronic illnesses observed in military following exposure to a variety of chemical weapons, depleted uranium, combat stress, and vaccines.
Fatigue, muscle weakness, myalgia, cognitive impairment, rash, diarrhea
Unclear etiology - no link to squalene

Question 34

What is vaccine-associated paralytic poliomyelitis? What is the incidence rate?

Answer 34

Reversion of vaccine strain to a neurovirulent strain of virus (oral polio vaccine)
Incidence rate - 1:2,400,000 cases

Question 35

What is a possible risk from the rotavirus vaccine?

Answer 35

Intussusception

1~2:100,000 infants

Question 36

What are the four childhood vaccines?

Answer 36

Pentavalent combination (Diptheria toxoid, tetanus toxoid, acellular or whole killed pertussis, inactivated poliomyelitis, H.influenza serotype b)
Pneumococcal vaccine (strep pneumoniae polysaccharides or conjugated to modified DT)
Meningococcal (neisseria meningititis polysaccharides or conjugated to modified DT/TT)
MMR (measles mumps rubella all live attenuated)

Question 37

What are the adult vaccines?

Answer 37

Human papillomavirus
Poliovirus (salk killed oral poliovirus vaccine)
Influenza virus (2 A serotypes and 1 B serotype, live attenuated or killed whole)
Tetanus (toxoid vaccine, booster every 10 years)

Question 38

What are the vaccinations for travel to high risk areas?

Answer 38

Hep A
Hep B
Yellow fever virus
Salmonella typhi (typhoid fever)
Vibrio cholera

Question 39

Why do some vaccines need boosters?

Answer 39

Duration of protection of different vaccine formulations is highly variable. Many influences on the maintenance of memory T cell and memory B cells. Some vaccines require booster shots to re-stimulate the immune system
Some vaccines schedules requires multiple stimulations to achieve lifelong immunity (HPV, HAV, HBV)

Question 40

What are current vaccines in development?

Answer 40

HIV vaccines

Cancer vaccines

Question 41

What is the MOA of cancer vaccines?

Answer 41

Post exposure prophylaxis, therapeutic vaccines
Vaccine immunizes against tumor-associated antigens (TAAs)
Many clinical trials in progress

Question 42

What are the emerging vaccine platforms?

Answer 42

DNA-based vaccines
Dendritic cell-based vaccines (stimulate with DC with antigen to achieve antigen presentation. DCs removed and then immunized via peptide/DNA/viral vector. Immunized DCs are reintroduced to the patient to stimulate immune response)
Plant based vaccines (transgenic plants to produce large-scale subunit vaccines)
CAR vaccines (Chimeric antigen receptors, stimulates T cell mediate response associated with better antitumor responses)