ANTIGENS_.pptx ( Ranjitha SL) PRESENTATION SLIDE

Antigen, properties, types, epitope and paratopes, hapten, factor Influenceing antigens, tests , importance

1. KUVEMPU UNIVERSITY PG DEPARTMENT OF BIOTECHNOLOGY SAHYADRI SCIENCE COLLEGE SHIVAMOGA. SEMINAR TOPIC ANTIGENS SUBMITTED BY UNDER THE GUIDENCE OF RANJITHA SL , Dr. BANUMATHI , I MSc BIOTECHNOLOGY , LECTURER , Email Id: [email protected] PG DEPARTMENT OF BIOTECHNOLGY, SAHYADRI SCIENCE COLLEGE , SAHYADRI SCIENCE COLLEGE , SHIVAMOGGA . SHIVAMOGGA .

2. CONTENT INTRODUCTION ANTIGENS EPITOPES TYPES HAPTENS PROPERTIES/FACTORS ADJUVENTS TESTS IMPORTANCE CONCULSION REFERENCES

3. ANTIGENS

4. INTRODUCTION Antigens are molecules that tigger an immune response in the body they are recognised by the immune system as foreign or non self .the immune system then mounts a defense against these antigens. Often by producing antibodies. Antigens can be found on the surface of bacteria, viruses, parasites, and other foreign invaders. They can be also be present in substances like pollen, dust mites . The immune response is able to distinguish b/w self and non – self antigens, allowing it to target foreign substances without attacking the body’s own tissues.

5. ANTIGENS An antigen is any substance that causes your immune system to produce antibodies against it.. It can be protein ,carbohydrates , lipids or nucleic acid .

6. PROPERTY OF ANTIGENS IMMUNOGENICITY : The ability to induce a humor/cell mediated response is a property of a substance known as antigen called immunogen. B cell +Antigen →Effector B cell (plasma cell) +memory B cell. T cell +Antigen →Effector T cell (Th/Tc)+memory T cell. ANTIGENICITY : The ability to combine specifically with antibodies or cell surface receptors. all molecules that have the property of immunogenicity also have the property of antigenicity.

7. EPITOPES EPITOPE(ANTIGENIC DETERMINANT) The part of an antigen that is recognized by antibodies ,B cells and T cells. It includes sugars, organic acids and bases, amino acid chains, hydrocarbons and aromatic groups. The number of epitopes called ‘valency’ Each epitopes is recognized by a different antibody. The Antibodies contains antigen binding site called ‘PARATOPES’

8. TYPES OF ANTIGEN

9. EXOGENOUS ANTIGENS ❶ ORIGIN ❷ PROCESSING ❸ IMMUNE RESPONSE Exogenous antigens are foreign substances that originate outside the body. Once exogenous antigens enter the body ,they are taken up by immune cells, primarily antigen-presenting cells(APCs). The presentation of exogenous antigen on APCs triggers an immune response. They enter the body through various routes such as inhalation ,ingestion or injection. APCs process their antigen and present them on their surface in a way that is recognizable by the other immune cells This involves the activation of T Cells and B Cells They come from sources like bacteria , viruses, fungi, parasites and allergens The leading to the production of the antibodies and cytotoxic then T- Lympocytes that can target and eliminate the invading pathogen.

10. ENDOGENOUS ANTIGENS ❶ ORIGIN ❷ EXAMPLES These antigens are produced within the cells of the body Endogenous antigens includes viral proteins, when viruses infect a cells they take over the cells machinery and produces viral proteins They aren't foreign invaders like exogenous(bacteria/viruses) instead, they are generated by normal cellular processes, such as protein synthesis and degradation. These processes can sometimes leads to the production of abnormal or altered protein that the immune system recognize as foreign.

11. AUTO ANTIGENS ❶ SELF RECOGNISATION ❷ IMMUNE DYSREGULATION ❸ TISSUE DAMAGE The immune system normally distinguishes between self and non self. Autoimmune disorder occur when the immune system loses tolerance for self antigen Autoantigens can trigger the production of antibodies and T cells that attack the body's own tissues. Autoantigens are molecules that are normally found within the body ,but are mistakenly recognized as foreign by the immune system. This can happen due to a variety of factor , including genetic predisposition, environment triggers , and infections. This can lead to a wide range of symptoms depending on the specific tissues and organs involved This can lead to autoimmune diseases When the immune system attacks self antigens, it can cause damage to tissue and organs

12. TUMOR ANTIGENS Tumor antigen are those antigens that are presented by the MHC – I (Major Histocompatibility Complex) molecules on the surface of tumor cells. These antigens can sometimes be presented only by tumor cells and never by the normal ones . In this case they are called tumor specific antigens ( TASAs)and typically result from a tumor specific mutation . These antigens are not membrane protein but are derivatives of cytosolic protein. Eg : NY – ESO – 1( Cancer testis antigen,HER2/neu (Breast cancer antigen)

13. ON THE BASIS OF THE IMMUNE RESPONES

14. BASED ON FUNCTION Classified into types: COMPLETE ANTIGEN : Substances which can induced antibody formation by themselves and can react specifically with these antibodies. Eg : Influence vaccine, Hepatitis B surface antigen. INCOMPLETE ANTIGEN/HAPTENS :Substances unable to induce antibody formation on its own but can become immunogenic when covalently linked to protein ,called carrier protein . Eg : TNP(trinitrophenol)

15. HAPTENS Haptens is derived from the Greek word haptein mean “to fasten”. The term Hapten was first coined by karl Landsteiner . These are low molecular weight substance that are antigenic but not immunogenic Its biological importances substances-drugs ,peptide hormones , steroid hormones , can function as hapten. Eg :Penicillin

16. DIFFERENCE B/w ANTIGEN AND HAPTENS Antigens Haptens An antigen is a foreign body, which has the ability to trigger the host immune system to produce an immune reaction by binding to an antibody. A Hapten is an incomplete antigen which is not originally immunogenic. Antigen directly binds to the antibodies produced and initiate an immune reaction . Hapten binds to an antibody but does not have the ability to trigger the hoist immune system to produce an immune reaction. Antigens are not conjugating with a carrier molecule. Haptens conjugate with carrier molecules . Antigens are used in vitro techniques such as ELISA and in pharmacological purpose. Haptens are used in Antibiotics and Anesthetics designing. Antigen reactions are Antigenic and immunogenic. Hapten reaction are only Immunogenic.

17. BASED ON BIOLOGICAL CLASSES OF ANTIGENS

18. PROPERTIES /FACTORS INFLUENCING OF IMMUNOGENICITY FOREIGNNESS Antigen must be foreignness to immune system According to Burnnet ’s clone selection theory , “ foreignnes (non – self) means substances that never contact with lymphocytes embryo period. Higher in the phylogenetic distance between the antigen and the host is more in the immunogenicity

19. CONTINUE… 2.CHEMICAL NATURE AND COMPOSITION Antigen are mainly proteins and polysaccharides Chemical nature of antigen protein ,polysaccharides ,nucleoproteins ,glycoprotein ,steroid hormones ,bacterial cells ,viruses Lipid and nucleic acids are less antigenic on their own but do so when combined with proteins / Polysaccharides Protein>Polysaccharides>>Lipids , nucleic acid

20. CONTINUE….. 3. MOLECULAR SIZE The antigens have a molecular mass of 14000 to 600000 Da Highly antigenic are tetanus toxoid (50000),Egg albumin(42700 Da),Thyroglobulin (662000 Da) 4.DEGRADABILITY Antigens that are easily phagocytosed are generally more immunogenic. This is because for most antigen (T-dependent antigens) the development of an immune response that the antigen be phagocytosed , processed to helper T –cells by an antigen presenting cell (APC4 ).

21. CONTINUE….. 5.DOSE AND CONCENTRATION: Optimum doses and concentration can trigger stronger immune responses. 6.GENETIC FACTORS: Genetic polymorphism and epigenetic modification can affect immune responses to specific antigens.

22. 7.ROUTE OF ADMINISTRATION Generally the subcutaneous routes is a better than the intravenous or intragastric routes. Administration route strongly influences which immune organs and cells populations will be involved in the response. Eg : Intravenous (Spleen),Subcutaneous(local lymph nodes)

23. ADJUVENTS Substances that when mixed with an antigen and injected with it ,enhance the immunogenicity of that antigen. Used to boost the immune response when an antigen has low immunogenicity or when small amount of antigen are available Eg: The antibody response of mice to immunization with BSA can be increased 5 fold or more ,if the BSA is administered with an adjuvant . Freund’s incomplete adjuvant : contains aqueous solution , mineral oil , mannide monooleate. Freund’s complete adjuvant :Heat killed Mycobacteria,Muramyl dipeptide .

24. TESTS FOR ANTIGENS ELISA RIA CFT IMMUNOFLUORESENCE NEUTRALIZATION TEST IMMUNOHISTOCHEMISTRY

25. IMPORTANCE OF ANTIGENS Triggering immune response Specificity Activation of immune cells Antibody production Immunological memory Vaccine development Cancer Research and study Diagnostic Tools Immunotherapy development

26. CONCULSION Antigens are substances that stimulate an immune response , playing a crucial role in the body’s defense against pathogens and diseases .they can originate from inside or outside the body , antigens trigger an immune response.

27. REFERENCES 1.Kuby, J.(2013),Immunology (7 th ed.). W.H.Freeman and company 2.Gangal,Sudha and Shubhangi Sontakke (2020) ,Textbook of Basic and Clinical Immunolo ., gy . (3 rd ed )CBS Publisher

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