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

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Presentation on theme: "Applied Immunology Aftab Jasir, European Centre for Disease Prevention and Control (ECDC) European Public Health Microbiology training program (EUPHEM)"— Presentation transcript:

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 Cells Immunoglobulins

6 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) Definitions/terminology

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


12 Factors influencing immunogenicity Factors Contribution of immunogen Contribution of biological system Method of administration

13 Immunogenicity: contribution of biological system Genetics Species Individual Responders vs Non-responders Age

14 14 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

15 My face is my fortune Where are you going, my pretty maid? Im going a-milking, sir, she said May I go with you, my pretty maid? Youre 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


17 Variolation The word variolation comes from the Latin word variola for human smallpox. source: Claire JP Boog

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


20 20 Edward Jenner Among patients awaiting small pox vaccination

21 Types of acquired immunity

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

23 Mode of delivery

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

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

26 26 Serology A science that attempts to detect signs of infection in a patients 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.

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

28 28 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.

29 29 Examples of serological tests 1.Agglutination tests 2.Precipitation tests 3.Immunoelectrophoresis 4.Western blot tests 5.Complement fixation tests 6.Immunofluorescence testing 7.Immunoassays

30 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.

31 ELISA unknown amount of antigen is affixed to a surface 2.a specific antibody is applied over the surface that binds to the antigen 3.antibody is linked to an enzyme 4.a substance is added that the enzyme can convert to some detectable signal, most commonly a colour change in a chemical substrate

32 32 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

33 33

34 Importance for epidemiologist Ex1 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?

35 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??

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

37 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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