Chpt 18 Practical Applications of Immunology

Practical Applications of Immunology
Chapter 18
I Vaccines (injection of antigens)
A. Principles and Effects of Vaccination
1. vaccine: a suspension of microorganisms, or some part or product of them, that will induce immunity when it is administered to the host.
2. herd immunity: when most, but not all, of the population is immune
B. Types of Vaccines and their characteristics
1. Inactivated (killed) Organism Vaccines: injection of killed mo
a. killed by:
i. phenol
ii. formalin
b. examples:
i. influenza: inactivated influenza virus
ii. rabies: inactivated rabies virus
2. whole agent
3. attenuated (weakened) whole agent: mimic actual infection and usually provide better immunity.
a. injection of weakened strain of mo
b. disadvantage: organism can become virulent
c. examples:
i. measles (MMR) attenuated measles virus
ii. TB (BCG) Mycobacterium bovis
4. Subunit (Component)Vaccines: uses only those antigenic fragments of a mo that are best suited to stimulate an immune response.
a. injection of part of microorganism
b. advantages: safe
c. examples:
i. tetanus: toxoid of Clostridium tetani (toxoid: inactivated bacterial virus)
ii. HIB: polysaccharide of Haemophilus influenzae
iii. Hepatitis B: HBV surface antigen (HBsAg)
5. Carrier Vaccines: injection of harmless organism
a. containing/expressing gene from disease causing organism
6. DNA vaccines
a. injection of DNA from mo
b. new technology
7. Passive immunization
a. injection of antibodies
b. instant immunity
c. protection lasts 5-6 months
d. examples
i. antivenom (antivenin)
II Diagnostic Immunology
A. Essential diagnostic tests for determining immunity:
1. sensitivity: the probability that the test is reactive if the specimen is a true positive
2. specificity: the probability that a positive test will not be reactive if a specimen is a true negative
A. Monoclonal Antibodies and their uses
B. Precipitation Reactions: involve the reaction of soluble antigens with IgG or IgM antibodies to form large lattices.
1. Ag - IgM or IgG react to form a complex
2. Ag – Ab complex form lattices and precipitate from solution
3. Ag – Ab ratio is optimal
4. Antigens – soluble
5. Immunoprecipitation: antigens and antibodies precipitate in agarose
6. Remember these test from lab.
C. Agglutination Reactions: involve particulate antigens that can be linked together by antibodies.
1. Direct agglutination
a. cells to be identified are agglutinated by antibodies.
b. titer: concentration of antibody in a serum
2. Indirect (passive) agglutination
a. antibodies or antigens are attached to plastic beads
b. beads clump
c. easy to do
D. Neutralization Reactions
1. antitoxin
2. viral hemagglutination inhibition test
E. Complement-fixation reactions
F. Fluorescent-antibody techniques (immunofluorescence)
1. antibodies labeled with a fluorescent dye
2. can look for antigens or antibodies
3. dyes are combined with antibodies to make them fluoresce when exposed to ultraviolet light.
4. methods:
a. direct
b. indirect
G. Enzyme-Linked Immunosorbent Assay (ELISA)
1. antibodies are labeled with an enzyme in a micro titer plate
2. enzyme causes color change for positive result
3. flexible, sensitive
4. home tests: early pregnancy tests
5. methods:
a. direct: goal is to identify an unknown antigen such as a drug in a serum sample
b. indirect: object is to determine the presence of certain antibodies in the serum. (AIDS virus)