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Applied Immunology

Applied Immunology. Aftab Jasir , European Centre for Disease Prevention and Control (ECDC) European Public Health Microbiology training program (EUPHEM). Objectives. Define basic components of immune system Define important terms in immunology Explain major applications of immunology.

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Applied Immunology

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  1. Applied Immunology Aftab Jasir, European Centre for Disease Prevention and Control (ECDC) European Public Health Microbiology training program (EUPHEM)

  2. Objectives Define basic components of immune system Define important terms in immunology Explain major applications of immunology

  3. What is immunology? • Immunology is a broad branch of biomedical science that covers the study of all aspects of the immune system in all living organisms. • It deals with the physiological functioning of the immune system in states of both health and disease

  4. What is the immune system? The immune system is the ministry of defence of the human/animal body

  5. Major defence components of the human immune system Immunoglobulins Cells

  6. Definitions/terminology Antigens (Ag) Large molecules, is anything that obtain the formation of a specific immune response (Anomy) Ag determinants (epitopes)are the particular chemical groups on a molecule that are antigenic Antibody(Ab)/immunoglobulin (Ig). A special group of soluble proteins that are produced in response to foreign antigens (substances)

  7. Antigen and antibody

  8. Haptens

  9. 5 classes of IGs a. IgG (secondary exposure, small, passing placenta) b. IgM(first exposure, large, not passing placenta, huge amont) c. IgA (mucosal immunity, respiratory tract) d. IgE (Allergy and parasites) e. IgD (proteins in the plasma membranes of mature B-lymphocytes, same time as IgM)

  10. Ministry of defence of the human body

  11. Factors influencing immunogenicity

  12. Immunogenicity: contribution of biological system • Genetics • Species • Individual • Responders vs Non-responders • Age

  13. Major practical applications of immunology • Use of antiserum and vaccination to provide protection against disease. • Diagnostic tool to detect disease. • Epidemiological investigation of vaccine preventable diseases 14

  14. My face is my fortune Where are you going, my pretty maid?I’m going a-milking, sir, she said May I go with you, my pretty maid?You’re kindly welcome, sir, she said What is your father, my pretty maid?My father is a farmer, sir, she said What is your fortune, my pretty maid?My face is my fortune, sir, she said

  15. Variolation • The word ‘variolation’ comes from the Latin word ‘variola’ for human smallpox. source: Claire JP Boog

  16. Discovery of small pox vaccine Blossom Edward Jenner 1780AD 18

  17. Edward JennerAmong patients awaiting small pox vaccination 20

  18. Types of acquired immunity

  19. Passive – receive Abs made by another 1. natural 2. artificial - γ globulin, hyperimmune serum Artificial Natural

  20. Mode of delivery

  21. Disadvantages Advantages Advantages and Disadvantages of Active Immunization • Not immediate Immune suppressed/deficiency • Long term immunity • Herd immunity • Risk of infection • Risk of contamination • Animal ??? • Attenuated can revert to their pathogenic form 24

  22. Disadvantages Advantages Advantages and Disadvantages of Passive Immunization no long term protection serum sickness immediate protection risk of hepatitis and AIDS graft vs. host disease 25

  23. Serology • A science that attempts to detect signs of infection in a patient’s serum such as Ab for a specific microbe • Serological tests based on Abs specifically binding to Ag • Ag of known identity will react with Ab in an unknown serum sample. • Known Ab can be used to detect Ag in serum • Ag-Ab reactions are visible by clumps, precipitates, color changes or release of radioactivity. • The most effective tests have high specificity and sensitivity. 26

  24. a) The presence of a specific Ab b) Identification of microbes 27

  25. Specificity, sensitivity, and cross reactivity a) Specificity • Ab attaches with great exact-ness to only one type of Ag. b) Sensitivity • Ab can locate Ag, even when it is greatly diluted. c) Cross reactivity • the ability of an individual antibody combining site to react with more than one antigenic determinant or the ability of a population of antibody molecules to react with more than one antigen. 28

  26. Examples of serological tests Agglutination tests Precipitation tests Immunoelectrophoresis Western blot tests Complement fixation tests Immunofluorescence testing Immunoassays 29

  27. ELISA • Enzyme-linked immunosorbent assay (ELISA), also known as an enzyme immunoassay (EIA), • is a biochemical technique • used mainly in immunology to detect the presence of an antibody or an antigen in a sample. • has been used as a diagnostic tool in medicine as well as a quality control check in various industries.

  28. ELISA • an unknown amount of antigen is affixed to a surface • a specific antibody is applied over the surface that binds to the antigen • antibody is linked to an enzyme • a substance is added that the enzyme can convert to some detectable signal, most commonly a colour change in a chemical substrate

  29. Agglutination tests • Ab cross-links whole cell Ag, forming complexes that settle out and from visible clumps in the test chamber • Purpose of agglutination testing: • Qualitative testing blood typing, some bacterial & viral diseases. • Quantitative testing Used to detect titer (maxium dilution that will still give visible agglutination) Difference between agglutination and precipitation? • Agglutination => clumping together of insoluble molecules • Precipitation => aggregation of soluble molecules 32

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  31. Importance for epidemiologistEx1 • 2005, outbreak of Salmonella like illness in Skåne ) Sothern Sweden=, in the same time report from Denmark of Salmonella enterica. • Diagnostic of pathogen in Sweden was not successful • Many of patients had common sort of relation (eating in the same restaurant, buying meat from same market or meat imported from Denmark) • Media reported a new sort of (unknown) infection • Speculation of new type of Salmonella among doctors • 6 days later Salmonella enterica was detected in the main lab in Skåne • What was wrong?

  32. Ex2 • 1999, Outbreak of scarlatina like (Scarlet fever) in 2 daycares in Lund, Sweden • 28 Children were diagnosed by symptoms • Two teacher, one working in both daycares, one developed STSS • No Lab confirmation of Group A streptococci • Microscopy showed gram positive chained bacteria • One weak later two children were confirmed by lab results having Group A streptococci • What was wrong know??

  33. Diagnostic of viral infections infection early phase late phase of infection amount of virus antigen/genome amount of antibodies detection limit months days years virus detection PCR, capture-ELISA virus isolation, electron- microscopy, hybridisation serology tests immunofluorescence, NT ELISA, immunoblot, HIA Prof. Matthias Niedrig, RKI

  34. What should you have in mind!!! • Some times Ag x Ab based tests can results in wrong alarm of outbreak ( Salmonella) • Antigen variation is always a problem (Chlamydia, grouping of streptococci) • Cross-reactivity can give wrong information of an outbreak • Any unusual or unexpected results should be confirmed by genetic test • If possible use other methods than serology in an outbreak situation or combine with other methods

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