Lecture 22

Question 1

What is a vaccine?

Answer 1

suspension of organisms or fractions of organisms that induce immunity

Question 2

What is variolation?

Answer 2

inoculation of smallpox into the skin

Question 3

What is the purpose of a vaccination?

Answer 3

• provokes a primary immune response which leads to the formation of antibodies and memory cells
• produces a rapid, intense secondary response
• herd immunity: most of the population is immunity

Question 4

What are live attenuated vaccines?

Answer 4

• weakened pathogen
• closely mimic an actual infection
• confers lifelong cellular and humoral immunity

Question 5

What are inactivated killed vaccines?

Answer 5

• safer than live vaccines
• require repeated booster doses
• induce mostly humoral immunity

Question 6

What is subunit vaccines?

Answer 6

use antigenic fragments to stimulate an immune response

Question 7

What are examples of subunit vaccines? What are the differences?

Answer 7

• recombinant vaccines: produced by genetic modification
• toxoids: inactivated toxins
• virus-like particle vaccines: resemble intact viruses but do not contain viral genetic material

Question 8

What are polysaccharides vaccines?

Answer 8

made from molecules in pathogen’s capsule
- not very immunogenic

Question 9

What are conjugated vacciens?

Answer 9

used for diseases in children with poor immune response to capsular polysaccharides

Question 10

What are nucleic acid vaccines?

Answer 10

• injected naked DNA produces the protein antigen encoded in the DNA
• stimulate humoral and cellular immunity

Question 11

What are recombinant vector vaccines?

Answer 11

avirulent viruses or bacteria are genetically modified to deliver genes coding for antigens

Question 12

What are the different types of vaccines?

Answer 12

• without animal host
• plants
• oral vaccines
• dry vaccines (skin patch)
• multiple-combination vaccines
• vaccines for chronic diseases
• reverse vaccinology

Question 13

What are adjuvants?

Answer 13

chemical additives added to vaccines to improve effectiveness
- improve the innate immune response

Question 14

What are the approved adjuvants in the US?

Answer 14

• alums
• monophosphoryl lipid A

Question 15

What is sensitivity?

Answer 15

probability that the test is reactive if the specimen is a true positive

Question 16

What is specificity?

Answer 16

probability that a positive test will not be reactive if a specimen is a true negative

Question 17

When do we use immunologic-based diagnostic tests?

Answer 17

• interactions of humoral antibodies with antigens
• known antibody can identify an unknown
• known pathogen can identify an unknown antibody

Question 18

What is hybridoma?

Answer 18

immortal cancerous B cell (myeloma) combined with an antibody-producing normal B cells
- produces monoclonal antibodies

Question 19

What are monoclonal antibodies used for?

Answer 19

• diagnostic tools
• human therapy
  = neutralize TNF block the progression of rheumatoid arthritis
  = treat allergic asthma by preventing the binding of IgE on mast cells and basophils

Question 20

Where do monoclonal antibodies come from?

Answer 20

mouse cells

Question 21

What are chimeric monoclonal antibodies?

Answer 21

mabs with a mouse variable region and human constant region

Question 22

What are humanized antibodies?

Answer 22

mabs that are mostly human, except for mouse antigen-binding sites

Question 23

What are fully human antibodies?

Answer 23

mabs produced from a human gene on a mouse

Question 24

What is the precipitin ring test?

Answer 24

cloudy line forms where there is the optimal ratio of antigen and antibody

Question 25

What are immunodiffusion tests?

Answer 25

precipitation reactions carried out in an agar gel medium - precipitate forms where the optimal antigen-antibody ratio occurs

Question 26

What is immunoelectrophoresis?

Answer 26

combines electrophoresis with immunodiffusion - separates proteins in human serum

Question 27

What are agglutination reactions?

Answer 27

particulate antigens binding to antibodies to form visible aggregates

Question 28

What are direct agglutination tests?

Answer 28

- detect antibodies against large cellular antigens - measures concentration of serum antibody (titer) = rise in titer indicates a greater immunity to disease

Question 29

What is seroconversion?

Answer 29

significant change in titer as a disease progresses

Question 30

What is indirect (passive) agglutination tests?

Answer 30

antibody reacts with the soluble antigen adhering to the particles

Question 31

What is hemagglutination?

Answer 31

agglutination of RBC surface antigens and complementary antibodies - used in blood typing

Question 32

What is viral hemagglutination?

Answer 32

occurs when viruses agglutinate RBCs without an antigen-antibody reaction

Question 33

What diseases have viral hemagglutination?

Answer 33

- mumps - measles - influenza

Question 34

What are neutralization reactions?

Answer 34

antigen-antibody reaction where the harmful effects of an exotoxin or a virus are blocked by antibodies to the toxin (antitoxin)

Question 35

What is the viral hemagglutination inhibition test?

Answer 35

used for subtyping viruses - viruses and RBCs are mixed with the patient's serum - if the serum contains antibodies to a virus, they neutralize the virus and inhibit hemagglutination

Question 36

What are complement fixation?

Answer 36

complement serum protein binds to and is fixed to the antigen-antibody complex

Question 37

How do complement-fixation reactions work?

Answer 37

- detects small amount of antibody - works for antibodies that do not work with precipitation or agglutination reactions

Question 38

What do fluorescent-antibody techniques do?

Answer 38

combine fluorescent dyes with antibodies

Question 39

What do direct fluorescent-antibody tests do?

Answer 39

identifies microorganism in a clinical specimen

Question 40

What do indirect fluorescent-antibody tests do? How does it work?

Answer 40

detect specific antibody in serum - anti-human immune serum globulin (anti-HISG) is added and will react with any antibody in serum if the result is positive

Question 41

How does the fluorescence-activated cell sorter work?

Answer 41

- laser beam strikes a droplet containing a cell - detector determines size and fluorescence of surface molecules - imparts a charge to the cell, separating cells

Question 42

What is ELISA?

Answer 42

Enzyme-Linked Immunosorbent Assay

Question 43

What does direct ELISA do? How does it work?

Answer 43

detects antigens - sample with antigens is mixed with antibody - enzyme-linked antibodies react with the antigen - detected by adding a substrate for the linked enzyme

Question 44

What does indirect ELISA do?

Answer 44

detects antibodies

Question 45

What does western blotting do?

Answer 45

identifies proteins via electrophoresis and a blot

Question 46

What does the future of diagnostic and therapeutic immunology look like?

Answer 46

- increasing automation of tests - PCR and DNA probes - inexpensive and simple tests for developing countries - disease prevention and therapy

Question 47

What are some challenges with getting a population vaccinated?

Answer 47

- poverty - lack of health infrastructure - boosters - avoidance