1. Chapter 6
Immunization

2. Immunization Two Artificial Methods of Immunity
Active immunization – administration of a vaccine so that the patient actively mounts a protective immune response
Passive immunization – individual acquires immunity through the transfer of antibodies formed by an immune individual or animal

3. Immunization Brief History of Immunization
The Chinese noticed that children who recovered from smallpox did not contract the disease again
They infected young children with material from a smallpox scab to induce immunity in these children, a process known as variolation
The use of variolation spread to England and America but was stopped due to risk of death

4. Immunization Brief History of Immunization
1796 – Edward Jenner discovered process of vaccination by inoculating material from a person infected with cowpox
1879 – Louis Pasteur developed a vaccine against Pasteurella multocida
Practice of transferring antibodies was developed when it was discovered vaccines protected through the action of antibodies

5. Immunization
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6. Immunization Brief History of Immunization
Socioeconomic and political problems prevent many developing nations from receiving vaccines
Effective vaccines unable to be developed for some pathogens
Vaccine-associated risks discourage investment in developing new vaccines

7. Immunization Active Immunization Vaccine types
Attenuated (live) vaccines
Use pathogens that have reduced virulence
Can result in mild infections but no serious disease
Contain active microbes that stimulate a strong immune response due to the large number of antigen molecules
Can provide contact immunity through vaccinated individuals infecting those around them
Can be hazardous because modified microbes may retain enough residual virulence to cause disease

8. Immunization Active Immunization Vaccine types
Inactivated (killed) vaccines
Whole agent vaccines – produced with deactivated but whole microbes
Antigenically weak because the microbes don’t reproduce and don’t provide many antigenic molecules to stimulate the immune response
Often contain adjuvants, chemicals added to increase the effective antigenicity

9. Immunization
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10. Immunization Active Immunization
Acellular vaccine – contain only certain component of microbes,
Toxoid vaccines
Chemically or thermally modified toxins used to stimulate active immunity
Useful for some bacterial diseases
Stimulate antibody-mediated immunity
Require multiple doses because they possess few antigenic determinant
Subunit vaccines – produced with antigenic fragments of microbes
Both types are safer than live vaccines because they cannot replicate or mutate to a virulent form
Conjugate vaccine

11. Immunization Active Immunization Vaccine types
Vaccines using recombinant gene technology
Research attempts to make vaccines that are more effective, cheaper, and safer
A variety of recombinant DNA techniques can be used to make improved vaccine

12. Immunization
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13. Immunization
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14. Immunization
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15. Immunization Active Immunization Vaccine safety
Problems associated with immunization
Mild toxicity most common
Pain at injection site or, in rare cases, general malaise or fever high enough to induce seizures
Risk of anaphylactic shock (severe allergic reaction)
Residual virulence from attenuated viruses
Allegations that certain vaccines against childhood diseases cause or trigger autism, diabetes, and asthma
Research has not substantiated these allegations

16. Immunization Passive Immunotherapy
Administration of antiserum containing preformed antibodies to a patient. Can be – gamma globulin portion containing antibodies Hyperimmune sera- ( g-globulins from selected donor) Antitoxin- antibodies against specific toxins , tetanus,diphteria
Used to provide immediate protection against a recent infection or an ongoing disease
Antisera has several limitations, including
Contains antibodies against many antigens
Can trigger allergic reactions called serum sickness
May be contaminated with viral pathogens
Antibodies of antisera are degraded relatively quickly
Limitations are overcome through development of hybridomas

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18. Immunization
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19. Immune Testing
Uses serology – study and diagnostic use of antigen-antibody interactions in blood serum
Uses immunological processes in two general diagnostic ways
Uses known antibodies to detect antigens associated with an infectious agent
Uses antigens to detect specific antibodies in a patient’s blood to determine exposure to a specific pathogen
Test chosen based on the suspected diagnosis, cost to perform the test, and the speed with which a result can be obtained

20. Immune Testing Precipitation Tests
One of the easiest of serological tests
Relies on fact that antigens and antibody mixed in the proper proportion form large macromolecular complexes called precipitates
Correct proportions are important to create precipitation
Two techniques determine optimal antibody and antigen concentrations
Immunodiffusion
Immunelectrophoresis

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22. Immune Testing
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23. Immune Testing
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24. Immune Testing Precipitation Tests Radial immunodiffusion
Used to measure the concentrations of specific antibodies or immunoglobulins in a person’s serum
Produces anti-antibodies – inject human antibodies into an individual of another species, where they will be antigenic and cause production of antibodies directed against the human antibodies
The human antibodies are the “antigen” in the test, and the anti-antibody is the antibody

25. Immune Testing
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26. Immune Testing Precipitation Tests Immunoelectrophoresis
Improves the resolution of an immunodiffusion test
Can resolve more than 30 distinct antigens at once
Commonly used to demonstrate the absence of a normal antigen or to detect the presence of excessive amounts of an antigen

27. Immune Testing Agglutination Tests
Agglutination occurs due to the cross-linking of antibodies with particulate antigens
Agglutination is the clumping of insoluble particles, whereas precipitation involves the aggregation of soluble molecules
These reactions are easy to see and interpret with the unaided eye
Hemagglutination, the agglutination of red blood cells, can be used to determine blood type

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29. Immune Testing
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30. Immune Testing Neutralization Tests Viral neutralization
Cytopathic effect – viruses introduced into appropriate cell cultures will invade and kill the cells
Ability of virus to kill culture cells is neutralized when virus is first mixed with antibodies against it
Absence of cytopathic effect indicates the presence of antibodies against the virus
Test is sensitive and specific enough to identify whether an individual has been exposed to a particular virus or viral strain

31. Immune Testing Neutralization Tests
Viral hemagglutination inhibition test
Useful for viruses that aren’t cytopathic
Based on viral hemagglutination, the ability of some viral surface proteins to clump red blood cells
Serum from an individual will stop viral hemagglutination if the serum contains antibodies against the specific virus
Commonly used to detect antibodies against influenza, measles, and mumps

32. Immune Testing The Complement Fixation Test
Based on the generation during complement activation of membrane attack complexes that disrupt cytoplasmic membranes
Used to detect the presence of specific antibodies in an individual’s serum
Can detect antibody amounts too small to be detected by agglutination

33. Immune Testing

34. Immune Testing Labeled Antibody Test
Uses antibody molecules that are linked to some molecular “label” that enables them to be easily detected
Used to detect either antigens or antibodies

35. Immune Testing Labeled Antibody Test Fluorescent antibody tests
Use fluorescent dyes as labels
Fluorescein is the most important dye used in these test
Fluorescein-labeled antibodies used in two types of tests
Direct fluorescent antibody test
Indirect fluorescent antibody tests

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37. Immune Testing
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38. Immune Testing Labeled Antibody Test ELISAs
Stands for enzyme-linked immunosorbent assay
Uses an enzyme as the label
Reaction of the enzyme with its substrate produces a colored product indicative of a positive test
Most common form of ELISA is used to detect the presence of antibodies in serum

39. Immune Testing
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40. Immune Testing Labeled Antibody Test ELISAs Antibody sandwich ELISA
Modification of the ELISA technique
Commonly used to detect antigen
Antigen being tested for is “sandwiched” between two antibody molecules

41. Immune Testing
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42. Immune Testing Labeled Antibody Test ELISAs Advantages of the ELISA
Can detect either antibody or antigen
Can quantify amounts of antigen or antibody
Easy to perform, inexpensive, and can test many samples quickly
Plates coated with antigen and gelatin can be stored for later testing

43. Immune Testing Labeled Antibody Test Western blot test
Technique for detecting antibodies against multiple antigens in a complex mixture
Can detect more types of antibodies and is less subject to misinterpretation than other tests

44. Immune Testing
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45. Immune Testing Recent Developments in Immune Testing
Simple immunoassays that give results in minutes
Useful in determining a preliminary diagnosis
Most common are immunofiltration and immunochromatography assays
Immunofiltration
Rapid ELISA that uses antibodies bound to membrane filters rather than polystyrene plates
Membrane filters have large surface area making the assay quicker to complete

46. Immune Testing Recent Developments in Immune Testing
Immunochromatography
Very rapid and easy to read ELISAs
Antigen solution flows through a porous strip where it encounters antibody labeled with either pink colloidal gold or blue colloidal selenium
Antigen-antibody immune complexes flow through a region and encounter antibody against them, resulting in a visible pink or blue line
Used in pregnancy testing to detect human chorionic growth hormone

47. Immune Testing
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48. Immune Testing
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