Presentation on theme: "Applied Immunology Aftab Jasir: European Centre for Disease Prevention and Control (ECDC) European Public Health Microbiology training program (EUPHEM)"— Presentation transcript:
Applied Immunology Aftab Jasir: European Centre for Disease Prevention and Control (ECDC) European Public Health Microbiology training program (EUPHEM) Introductory course, Menorca,2012
Objectives Define basic components of immunology Describe important terms in immunology Explain major applications of immunology
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
What is the immune system? The immune system is the ministry of defence of the human/animal body
Immunodeficiency and Immunosuppression Immunodeficiencyis a state in which the immune system's ability to fight infectious disease is low or entirely absent. Immunosuppression involves an act that reduces the activation or efficacy of the immune system. immunosuppression may occur as an adverse reaction to treatment of other conditions.
Major defence components of the human immune system Cells Immunoglobulins
Immune system Innate (nonspecific) 1 st line of defense Cellular components Humoral components Adaptive (specific) 2 nd line of defense Cellular components Humoral components Overview of the immune system
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
Antigen and antibody
5 classes of IGs 1.IgM (first exposure, large, not passing placenta, huge amont) 2.IgG (secondary exposure, small, passing placenta) 1.IgD (proteins in the plasma membranes of mature B- lymphocytes, same time as IgM) 1.IgA (mucosal immunity, respiratory tract) 1. IgE (Allergy and parasites)
Haptens Vaccine conjugate
Ministry of defence of the human body
Antibody Protection of the Host
Primary and secondary antibodies P: antibodies raised against an antigenic target of interest and are typically unconjugated. S: antibody that binds to primary antibodies or antibody fragments. They are typically labeled with probes that make them useful for detection,
Factors influencing immunogenicity Factors Contribution of immunogen Contribution of biological system Method of administration
Class Switching antibody titer time IgG IgG IgM IgM Biological mechanism that changes a B cell's production of antibody from one class to another, for example, from IgM to IgG.
Four phases of the primary response lag phase where no antibody is detected log phase in which the antibody titer rises logarithmically plateau phase during which the antibody titer stabilizes phase (decline) during which the antibody is cleared or catabilized
Kinetics of the Ab Response T-dependent Ag; 1 o Response Lag Log Plateau Decline Ag D a y s A f t e r I m m u n i z a t i o n A b T i t e r LAG LOG DECLINE PLATEAU
Kinetics of the Ab Response T-dependent Ag; 2 o Response Lag Log Plateau Decline 1 o Ag 2 o Ag D a y s A f t e r I m m u n i z a t i o n A b T i t e r
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
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
Variolation The word variolation comes from the Latin word variola for human smallpox.
Discovery of small pox vaccine Edward Jenner 1780AD Blossom
Types of acquired immunity
Passive – receive Abs made by another 1. natural 2. artificial - γ globulin, hyperimmune serum Artificial Natural
Mode of delivery
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
Advantages Disadvantages serum sickness immediate protection no long term protection graft vs. host disease risk of hepatitis and HIV Advantages and Disadvantages of Passive Immunization
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.
Enzyme (ELISA) Immunoassay Antigen anti-antigen antibody Enzyme conjugated to anti-Ig antibody (second antibody) Add substrate for enzyme
a) The presence of a specific Ab b) Identification of microbes
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.
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
Acute infection Onset of symptoms Primary infection Incubation Days WeeksMonthsYears
Onset of symptoms Primary infection Incubation IgM Days WeeksMonthsYears Acute infection
Onset of symptoms Primary infection Incubati on IgM IgG Days WeeksMonthsYears Acute virus infection
Onset of symptom s Primary infection Incubation IgM IgG Days WeeksMonthsYears IgG avidity Avidity = the sum of affinities between: antibody and antigen Acute virus infection
Onset of symptom s Primary infection Incubation IgM IgG Persistence IgG avidity Days WeeksMonthsYears Secondary infection or reactivation
Onset of symptoms Primary infection Viremia IgM IgG IgG avidity Days WeeksMonthsYears Secondary infection or reactivation
What should you have in mind!!! Tack home massage 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