Title: Applied Immunology
1Applied Immunology
Aftab Jasir, European Centre for Disease
Prevention and Control (ECDC) European Public
Health Microbiology training program (EUPHEM)
2Objectives
Define basic components of immune system Define
important terms in immunology Explain major
applications of immunology
3What 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
4What is the immune system?
The immune system is the ministry of defence of
the human/animal body
5Major defence components of the human immune
system
Immunoglobulins
Cells
6Definitions/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)
7Antigen and antibody
8Haptens
95 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)
10Ministry of defence of the human body
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12Factors influencing immunogenicity
13Immunogenicity contribution of biological system
- Genetics
- Species
- Individual
- Responders vs Non-responders
- Age
14Major 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
15My 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
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17Variolation
- The word variolation comes from the Latin word
variola for human smallpox.
source Claire JP Boog
18Discovery of small pox vaccine
Blossom
Edward Jenner 1780AD
18
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20Edward JennerAmong patients awaiting small pox
vaccination
20
21Types of acquired immunity
22Passive receive Abs made by another 1.
natural 2. artificial - ? globulin,
hyperimmune serum
Artificial
Natural
23Mode of delivery
24Advantages and Disadvantages of Active
Immunization
- Immune suppressed/deficiency
- Long term immunity
- Herd immunity
- Risk of infection
- Risk of contamination
- Animal ???
- Attenuated can revert to their pathogenic form
24
25Advantages and Disadvantages of Passive
Immunization
- risk of hepatitis and AIDS
25
26Serology
- 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.
26
27 a) The presence of a specific Ab b)
Identification of microbes
27
28Specificity, 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
29Examples of serological tests
- Agglutination tests
- Precipitation tests
- Immunoelectrophoresis
- Western blot tests
- Complement fixation tests
- Immunofluorescence testing
- Immunoassays
29
30ELISA
- 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.
31ELISA
- 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
32Agglutination 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 gt clumping together of insoluble
molecules - Precipitation gt aggregation of soluble
molecules
32
3333
34Importance 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?
35Ex2
- 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??
36Diagnostic of viral infections
Prof. Matthias Niedrig, RKI
37What 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 -