History and Types of Immunization

1. Chapter 17 Immunization and Immune Testing

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 [INSERT FIGURE 17.1]

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 • 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 • 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 [INSERT TABLE 17.1]

10. Immunization • Active Immunization • Vaccine types • 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

11. Immunization Animation: Host Defenses: Vaccines: Types

12. 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

13. Immunization [INSERT FIGURE 17.2]

14. Immunization [INSERT FIGURE 17.3]

15. Immunization [INSERT TABLE 17.2]

16. 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 • 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

17. Immunization • Passive Immunotherapy • Administration of antiserum containing preformed antibodies to a patient • Used to provide immediate protection against a recent infection or an ongoing disease • Antisera has several limitations, including • Contains antibodies against many antigens, not just the ones of interest • 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

18. Immunization [INSERT FIGURE 17.4]

19. Immunization [INSERT FIGURE 17.5]

20. 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

21. 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

22. Immune Testing [INSERT FIGURE 17.6]

23. Immune Testing [INSERT FIGURE 17.7]

24. Immune Testing [INSERT FIGURE 17.8]

25. 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

26. Immune Testing [INSERT FIGURE 17.9]

27. 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

28. 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

29. Immune Testing [INSERT FIGURE 17.10]

30. Immune Testing [INSERT FIGURE 17.11]

31. 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

32. Immune Testing • Neutralization Tests • Viralhemagglutination 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

33. 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

34. Immune Testing

35. 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

36. 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

37. Immune Testing [INSERT FIGURE 17.13]

38. Immune Testing [INSERT FIGURE 17.14]

39. 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

40. Immune Testing [INSERT FIGURE 17.15]

41. 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

42. Immune Testing [INSERT FIGURE 17.16]

43. 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

44. 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

45. Immune Testing [INSERT FIGURE 17.17]

46. 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

47. 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

48. Immune Testing [INSERT FIGURE 17.18]

49. Immune Testing [INSERT TABLE 17.3]