1. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 1 Antigen-Antibody Reactions in Vitro serology –branch of medical immunology concerned with antibody-antigen reactions in vitro

2. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 2 Agglutination agglutinates –visible clumps or aggregates of cells or particles e.g., Widal test –diagnostic for typhoid fever

3. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 3 Figure 33.9a

4. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 4 Figure 33.9b

5. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 5 Box 33.2

6. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 6 Viral hemagglutination Figure 33.10

7. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 7 Figure 33.11 titer = reciprocal of highest dilution positive for agglutination

8. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 8 Complement Fixation binding of complement to an antigen-antibody complex basis of diagnostic tests that determine if antibodies to an antigen are present in patient’s serum

9. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 9 Figure 33.12

10. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 10 Enzyme-Linked Immunosorbent Assay ELISA can be used to detect antigens in a sample can be used to detect antibodies in a sample

11. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 11 Figure 33.13 chromogen – colorless substrate of enzyme that when acted on yields a colored product

12. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 12 Flow Cytometry and Fluorescence flow cytometry –detects organisms in clinical samples –detection based on cytometric parameters or by use of fluorochromes fluorochromes often bound to antibodies or oligonucleotides flow cytometer –forces suspension of cells through laser beam and measures amount of light scattering of fluorescence –enumerates cells having certain characteristics

13. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 13 Immunoblotting (Western Blot) procedure –proteins separated by electrophoresis –proteins transferred to nitrocellulose sheets –protein bands visualized with enzyme-tagged antibodies sample uses –distinguish microbes –diagnostic tests –determine prognosis for infectious disease

14. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 14 Figure 33.14

15. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 15 Immunodiffusion precipitation reaction that occurs in agar gel medium two commonly used techniques –single radial immunodiffusion (RID) assay –double diffusion agar assay (Ouchterlony technique)

16. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 16 Figure 33.15a used to quantify antigen

17. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 17 Figure 33.15b precipitated immune complexes used to determine identity of antigen

18. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 18 Immunoelectrophoresis antigens first separated by electrophoresis according to charge antigens visualized by precipitation reaction has greater resolution than immunodiffusion assays

19. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 19 Figure 33.16

20. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 20 Immunofluorescence uses fluorescent dyes (fluorochromes) coupled to antibody molecules antigen-antibody binding detected by irradiating sample with appropriate wavelength two commonly used assays –direct immunofluorescence – used to detect antigen –indirect immunofluorescence – used to detect serum antibodies

21. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 21 Figure 33.17

22. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 22 Immunoprecipitation used to detect soluble antigens binding of bivalent or multivalent antibodies to antigen forms lattice that precipitates lattice formation occurs only when there is an optimal ratio of antigen to antibody

23. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 23 Figure 33.18

24. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 24 Liposomes artificially created spherical vesicles –formed by lipid bilayer enclosing aqueous compartment used to deliver antibody (or antigen) in an antigen-antibody binding assay color dye in liposome used to detect binding of antigen to antibody

25. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 25 Figure 33.19

26. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 26 Neutralization determines whether the activity of a toxin or virus has been neutralized by an antibody involves use of “indicator systems” to test for toxicity or infectivity –e.g., lab animals or tissue culture cells

27. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 27 Radioimmunoassay (RIA) purified antigen labeled with radioisotope competes with unlabeled standard for antibody binding amount of radioactivity associated with antibody is measured

28. Copyright © The McGraw-Hill Companies. Permission required for reproduction or display. 28 Serotyping antigen-antibody specificity used to differentiate strains (serovars or serotypes) of an organism Quelling reaction –swelling of capsular material following addition of antisera specific to a capsular type –used to differentiate strains of Streptococcus pneumoniae