Immunization Principles

How did inoculation of cowpox by Edward Jenner prevent smallpox infection?

Cross protective mechanism since they share some surface antigens and antibodies against cowpox can bind to smallpox and neutralize it

What is the purpose of vaccination?

• induce the generation of long-lived memory t and B cells that protect against subsequent infection without inducing disease

• Control the spread of infections in a population

• Provide immunity transferable to offspring

List some features of effective vaccines.

• safe

• Protective

• Give sustained protection

• Induces neutralizing antibody

• Induces protective T cells

• Practicality

  • Low cost per dose

  • Biological stability

  • Ease of administration

  • Few side effects

What type of immune response would provide optimal protective immunity against a virus?

CTL and neutralizing antibodies

What type of immune response would provide optimal protective immunity against an extracellular bacteria?

Th17 and opsonizing antibodies

Pros of passive immunization

Immediate protection

Cons of passive immunization

• humoral only

• Protection is temporary

• No memory conferred

• May interfere with active immunization

• Foreign Protiens can induce serum sickness

True or False: Fully virulent vaccines can be extremely protective and have long lasting immunity but may not be safe.

TRUE

How are live attenuated vaccines generated?

1. Pathogenic virus is isolated from a patient and grown in human cultured cells

2. Cultured virus is used to infect monkey cells

3. Virus acquires many mutations that allow it to grow well in monkey cells

4. Virus no longer grows well in human cells and can be used as a vaccine

What is targeted attenuation?

The virulence gene is isolated and removed from the virus that make it immunogenic but avirulent

What are the advantages to a killed vaccine?

• safe for people with weak immune systems

• Do not require refrigeration

• Can be used in pregnant animals and neonates

Disadvantages of killed vaccines

• May require multiple doses to achieve effective immunity

• Induce weaker immune response compared to live attenuated

• Mild side effects such as pain, redness, or swelling

Vectored Vaccines

Use a harmless, weakened virus as a carrier or vector to deliver genetic material for the target antigen into host cells

DNA vaccines

Small, circular piece of DNA that carries the gene for an antigen which allows cells to uptake it and transcribe it into mRNA and then translate to target antigen

mRNA vaccine

Deliver a small, synthetic piece of messenger RNA that contains instructions for a specific antigen

True or False: genetically engineered vaccines can contain any portion of a microbe.

TRUE

Vaccines that contain inactivated recombinant organisms or purified antigens derived from recombinant organisms are category:

1

Vaccines containing live organisms with gene deletions or heterlpgous marker genes are category:

2

Vaccines that contain live expression vectors expressing heterozygous genes for immunizing antigens or other stimulants are category:

3

Examples of category 1 vaccines?

• foot and mouth disease (VP1)

• Feline leukemia virus (gp70)

What is an example of a vaccine that is category 2?

Pseudorabies

Examples of category 3 vaccines?

• rabies & vaccina

• Newcastle disease and fowlpox

Adjuvant

Substance added to a vaccine to enhance the immune response

Why do vaccines have adjuvants?

• more cost effective

• Effective innate immune signals

• Good immunomodulary capacity

• High specific antibody production

• Antigen specific clonal expansion

• Generation of cytoplasmic T cells

• Long lasting adaptive immune response

• Makes antigen more potent

Common routes for vaccine administration

• SQ

• ID

• IM

• IV

• IN

• Inhalation

• Oral

Polyvalwnt vaccine

Vaccine designed to provide immunity against two or more strains or types of the same microorganism or antigen or even different microorganisms

True or False: adverse vaccine reactions occur in larger animals more commonly

FALSE

What factors affect vaccination schedules?

• timing and disappearance of maternal antibodies

• Importance of residual antibodies for continued protection

• Longevity of memory lymphocytes

• Risk of exposure and risk of illness

• Incubation period