Immunity and Vaccines

Question 1

What is passive immunity?

Answer 1

Protection transferred from another person or animal.
(Temporary)

Question 2

What is active immunity?

Answer 2

Protection produced by the person/animals own immune system.
(Longer-term protection)

Question 3

How is passive immunity acquired?

Answer 3

Transfer of antibodies via colostrum/milk/placenta

Question 4

What antibodies are seen in passive immunity?

Answer 4

IgA (mucosal immunity) and IgG (serum immunity)

Question 5

What diseases use passive immunity as treatment?

Answer 5

• Tetanus
• Hepatitis A and B
• Immunodeficencies

Question 6

Why does passive immunity end?

Answer 6

Due to catabolism of antibodies

Question 7

How does active immunity work?

Answer 7

Infection by a pathogen and subsequent resolution leads to the production of memory T and B plus plasma cells. Second infection of the same pathogen leads to a stronger, faster and more specific reaction.

Question 8

What are the two ways in which active immunity can be caused?

Answer 8

-Natural Infection (Immunological memory but also symptoms/ pathology)
-Vaccination (still want strong immunological memory but no/very limited symptoms)

Question 9

What are the requirements of vaccines for active immunity to occur?

Answer 9

• mimic natural infection (to activate immune system)
• limit side effects

Question 10

What are adjuvants?

Answer 10

Any substance that when given with an antigen enhances the immune response to that antigen. (Used in vaccines)

Question 11

How do adjuvants aid vaccines?

Answer 11

• reduce the amount of antigen required to induce protection
• increases the speed and magnitude of the response

Question 12

How does the Alum adjuvant work?

Answer 12

• slow release antigen
• can lead to DAMPS activating dendritic cells and macrophages
• Mainly TH2 activation (not cell mediated)

Question 13

What are the three vaccine approaches?

Answer 13

• live attenuated vaccine
  -killed vaccine
  -subunit vaccines including toxoid vaccines

Question 14

How do live attenuated vaccines work?

Answer 14

• still viable but reduced pathogenicity
• can cause infection but not disease
• strong, appropriate immune response
• cellular immunity
• humoral immunity (antibody mediated immunity)
• long lasting immunity

Question 15

What are the advantages of using the live attenuated vaccine?

Answer 15

• Multiple antigens
• Few immunisations
• Easy to produce without genome of pathogen
• May not require adjuvant

Question 16

How does the killed vaccine work?

Answer 16

• Pathogens are killed by heat (which can denture too many proteins antigens)
  -Pathogens are killed by chemicals (formaldehyde)
• weaker immune response (compared to live vaccines)
• good serum antibody response (little secretory IgA)
• Poor cell-mediated immunity created
• Booster shots usually required

Question 17

What are the advantages of using killed vaccines?

Answer 17

• multiple antigens
• stable
• safer than live vaccine
• no refrigeration required

Question 18

What are the disadvantages of using killed vaccines?

Answer 18

• Benn inefficient in the past
• lack of understanding about why it protects
• contamination with animal viruses (polio)
• initial preparation requires working with pathogen

Question 19

How do subunit and toxic vaccines work?

Answer 19

• specific purified pathogen subunit/ molecule
• toxoid vaccines induce antibodies against the bacterial exotoxins
• exotoxins can cause major symptoms
• weak immune response
• good serum antibody response
• no cell-mediated immunity
• booster shots required

Question 20

What are the advantages of using subunit and toxoid vaccines?

Answer 20

• limited antigens (less chance of cross reactivity)
• higher levels of safety and reproducibility
• no need for refigeration

Question 21

What are the issues with using subunit and toxoid vaccines?

Answer 21

• Toxoid = limited to a few bacterial diseases
• difficult to develop
• adjuvant required