The document discusses antigen-antibody interactions, including that an antigen induces an immune response and antibodies are produced by B cells to neutralize pathogens. It describes the specific chemical interaction between antibodies and antigens, with non-covalent interactions like hydrogen bonds and van der Waals forces forming the basis of this binding. Finally, it lists several immunological tests that utilize this interaction, such as radioimmunoassay, ELISA, Western blot, and immunofluorescence.

1. Antigen antibody interaction
Kalu ram sharma
M.Sc(biotechnology)
Manipal university jaipur

2. Antigen
• In immunology, an antigen is a molecule
capable of inducing an immune response on
the part of the host organism.

3. Antibody
• An antibody (Ab), also known as an
immunoglobulin (lg), is a large, Y-shaped
protein produced mainly by plasma cells that
is used by the immune system to neutralize
pathogens such as bacteria and viruses.

4. Antibody

5. Antigen-antibody interaction
• The antigen-antibody interaction is a
bimolecular association similar to an enzyme-
substrate interaction, with an important
distinction.

6. Antigen-antibody interaction
• Ag-Ab interaction is a specific chemical
interaction between antibodies produced by B
cells of the white blood cells and antigens
during immune reaction.
• In the fundamental reaction in the body by
which the body is protected from complex
foreign molecules, such as pathogens and
their chemical toxin.

7. Strength of Ag-Ab interaction
• The non-covalent interactions that form the
basis of Ag-Ab binding include hydrogen
bonds, hydrophobic interactions, and van der
Walls interaction.
• Because these interactions are individually
weak (compared with a covalent bond), a
large number of such interactions are required
to form a strong Ag-Ab interaction.

9. Visualizing concepts

10. • The interaction between an Ab and an Ag
depends on four types of noncovalent forces:
• (1) hydrogen bond:- in which a hydrogen atom
is shared between two electronegative atoms.
• (2) ionic bonds:- Between oppositely charged
residues.

11. • (3) Hydrophobic interaction:- in which water
forces hydrophobic groups together.
• (4) van der Walls interaction:- Between the
outer electron clouds of two or more atoms.

12. Immunologic tests
• (1)Radioimmunoassay (RIA)
• (2)ELISA
• (3)Western Blot
• (4)Immunoprecipitation
• (5)Immunoflurescence

13. (1)Radioimmunoassay (RIA)
• It is very sensitive in vitro assay technique
used to measure concentration of antigen (for
example , hormone levels in blood) by use of
antibodies.

14. (2)ELISA(Enzyme-Linked
Immunosorbent Assay)
ELISA is test that uses antibodies and color change to identify
a substance.
The ELISA has been used as a diagnostic tool in medicine and
plant pathology , as well as a quality-control check in
various industries.
• The following steps of ELISA:-
• (a)indirect ELISA
• (b)sandwich ELISA
• (c)competitive ELISA

15. ELISHA

16. (3)Western Blot
• The western blot sometimes called the protein
immunoblot.
• Used to identification of specific proteins in
mixtures.
• Proteins are separated on SDS-PAGE.
• Proteins then transferred to membrane.

17. (4)Immunoprecipitation
• Provides a quick and sensitive test for finding
proteins.
• Binds Ab to synthetic bead support
centrifuged.

18. (5)Immunoflurescence
• Provides a quick method for the identification
of pathogens and lymphocytes.
• There are currently 2 methods employed:-
(a)Direct staining
(b)Indirect staining

19. Application
• Antigen-antibody interaction is used in
laboratory techniques for serological test
blood compatibility and various pathogenic
infection.
• The most basic is ABO blood group
determination , which is useful for blood
transfusion.

20. References
• Kuby book
• www.google.wikipedia.com

21. •Thank you