Vaccination Strategies

Question 1

2 types of vaccines

Answer 1

• killed (inactivated): diptheria-tetanus-pertussis

- live (attenuated): yellow fever

Question 2

Vaccine

Answer 2

A preparation of living or inactivated pathogens used as an antigen

Question 3

Vaccination

Answer 3

Administration of a living or inactivated pathogen to induce an immune response

Question 4

Protective immunity

Answer 4

Vaccine induced effectors (antibodies) prevent re-infection
- long-lived plasma cells in the bone marrow to maintain antibody levels in the bloodstream to neutralize the pathogen at the site of pathogen invasion

Question 5

Immunological memory

Answer 5

Vaccine-induced memory lymphocytes will not prevent re-infection, but can prevent disease or reduce severity of disease
- vaccine-induced memory lymphocytes circulate thru secondary lymphoid tissues

Question 6

What determines longevity of plasma cells?

Answer 6

• differs with vaccines/antigens
• with apoptosis, antibody levels drop below level of protection, require boosters or a second infection will be established

Question 7

Memory lymphocytes are exported from ____

Answer 7

Germinal center

• rapidly reactivated to proliferate to provide protection and high levels in the bloodstream
• requires a sufficient incubation period

Question 8

Example of inactivated vaccine

Answer 8

• diptheria: inactivated toxin from corynebacterium diptheriae
• tetanus: inactivated toxin from clostridium tetani
• pertussis: surface protein antigen and the toxin from bordetella pertussis

Question 9

Characteristics of killed vaccines

Answer 9

• killed vaccines generally result in an antibody response

- very poor inducer of cytotoxic T cells

Question 10

How many doses of a primary, killed vaccine are required?

Answer 10

Multiple doses
- germinal centers are short-lived with killed vaccines (antigen is non-replicating so only a few lymph nodes are engaged)

Question 11

Adjuvant

Answer 11

Substances that enhance the immunogenicity of antigens

• aluminum hydroxide is common adjuvant in human vaccines
• maintains a deposit of antigen at the site of injection
• slow release of aluminum particles with antigen = uptake by macrophages and immature DCs

Question 12

Correlates of protection

Answer 12

Vaccine-induced immune responses that protect against disease
- antibodies must be present at the time of exposure to the pathogen

Question 13

Vaccine boosters DTP

Answer 13

Required every 10 years

- duration of effectors (antibody): D = 19 yrs, T = 11 yrs, P = 10 yrs

Question 14

Killed vaccines are handled as ____

Answer 14

Extracellular pathogen

- do NOT induce cytotoxic T cells

Question 15

Germinal centers of live vaccines

Answer 15

Germinal centers persist with replicating live vaccines

- adjuvant not required

Question 16

Live vaccine correlate of protection

Answer 16

Antibodies must be present at the time of exposure to the pathogen

Question 17

YF-17D

Answer 17

Induces DC maturation and cross-presentation

Question 18

Characteristics of live vaccines

Answer 18

Live vaccines can mimic a natural infection resulting in polyvalent immunity

• neutralizing antibody
• CD4+ helper T cell
• CD8+ cytotoxic T cells

Question 19

Why do some vaccines need a booster?

Answer 19

For diseases in which antibody levels strongly correlate with protection
- decision for a booster is based on the persistence of antibodies and the incubation period of the disease (pace of pathogenesis)

Question 20

Persistence of antibodies

Answer 20

• long lived plasma cells can have a finite lifespan (are not maintained after some vaccinations and require boosters)
• memory B cells are maintained for decades after most vaccinations and natural infections

Question 21

Seronegative

Answer 21

Absence of specific antibody

Question 22

Are seronegative individuals protected from Corynebacterium diptheriae toxin?

Answer 22

If they have missed their boosters, then they become seronegative
- strictly dependent on memory cells since receptors are lost
- memory response requires 3-5 days to kick in
- diptheria pace of pathogenesis occurs in 2-5 days
= seronegative individuals are NOT protected (memory response is longer than the incubation period)

Question 23

Are seronegative individuals protected from hepatitis B virus?

Answer 23

In viral diseases, the pace of pathogenesis is generally slow

• boosters are not recommended
• if you become seronegative, then you will be protected due to long 45 day incubation period