Serological tests - Serology For Lab Technicians

Serology for Lab Technicians - one year diploma

1. Lab Technician by, Miss Areesha Ahmad Senior Lecturer B.Sc (H), M.Sc , M.Phil and Ph.D scholar (Microbiology) Serology

2. Definition of Serology Serology is the scientific study of blood serum, especially with respect to the response of the immune system to pathogens or introduced substances. The term "serology" typically refers to the diagnostic examination of blood serum to identify antibodies, antigens, and other immunological components.

3. Purpose of Serology Serology is essential for understanding the body’s immune response to infections, diagnosing diseases, and monitoring immunity. It's commonly used in infectious disease diagnosis, transfusion medicine, and autoimmune disorder identification.

4. Principles of Serology The field is based on antigen-antibody reactions, where specific antibodies in the blood will bind to specific antigens, allowing for the detection of pathogens or immune responses. Various tests are designed to measure these interactions, helping to confirm exposure to bacteria, viruses, and other microorganisms.

5. Applications of Serology: Infectious Disease Diagnosis: Identifies exposure to viruses (e.g., HIV, hepatitis), bacteria, and other pathogens. Blood Typing: Essential for safe blood transfusions. Vaccine Response Monitoring: Helps assess immunity post-vaccination by detecting antibodies. Autoimmune Disease Detection: Detects antibodies directed against the body’s own tissues, aiding in autoimmune disease diagnosis.

6. Automated ELISA in Serology Enzyme-Linked Immunosorbent Assay (ELISA) is a popular serological test used to detect antibodies, antigens, proteins, and hormones. In recent years, automation of ELISA has revolutionized laboratory workflows by enhancing efficiency, reducing manual errors, and enabling high-throughput testing. Automated ELISA systems are crucial in large-scale testing settings, such as hospitals, diagnostic labs, and research institutions, where they are frequently used for infectious disease screening, clinical diagnostics, and immunology research.

7. Benefits of ELISA Automation Increased Throughput: Automated ELISA systems can process numerous samples simultaneously, enabling faster processing of high sample volumes , which is essential in outbreak scenarios or large-scale screenings. Consistency and Reduced Human Error: Automation reduces variability introduced by manual handling. Consistent pipetting , incubation times , and washing steps improve the accuracy and reproducibility of results.

8. Benefits of ELISA Automation Time Efficiency: Automation minimizes the time needed for each step, from sample preparation to data analysis, allowing laboratory staff to focus on other critical tasks. Enhanced Data Management: Many automated ELISA platforms are integrated with software that can store and manage data , generating reports and enabling easy retrieval for future analysis.

9. Definition of Antigen An antigen is any substance that triggers an immune response in the body, especially by stimulating the production of antibodies. Antigens are typically foreign substances , such as bacteria, viruses, fungi , toxins , or even proteins from transplanted tissues, which the immune system recognizes as "non-self." Each antigen has specific sites, known as epitopes, that bind to antibodies or immune cell receptors, initiating an immune response to neutralize or eliminate the threat. Antigens are essential in the body’s defense mechanisms and play a key role in diagnostics and vaccine development.

10. Antigen

11. Definition of Antibody An antibody is a specialized protein produced by the immune system in response to foreign substances, known as antigens, such as bacteria, viruses, or toxins. Antibodies recognize and bind to specific antigens with high specificity, neutralizing or marking them for destruction by other immune cells. Structurally, antibodies are Y-shaped molecules composed of two heavy chains and two light chains, with a variable region that allows them to bind uniquely to different antigens. They play a critical role in immunity by identifying and helping eliminate pathogens and are also called immunoglobulins ( Ig ).

12. Types of Antibodies There are five main classes of antibodies, also known as immunoglobulins ( Ig ) . Each type has a specific structure and function in the immune system: 1) IgG (Immunoglobulin G) The most abundant antibody in the blood and extracellular fluid. Provides long-term immunity and can cross the placenta to protect the fetus.

13. 2) IgA (Immunoglobulin A) Found in mucous membranes, saliva, tears , and breast milk . Protects body surfaces exposed to foreign substances, such as respiratory and digestive tracts. 3) IgM (Immunoglobulin M) The first antibody produced in response to an infection . Primarily found in the blood and lymph fluid, it is effective in forming complexes with pathogens .

14. 4) IgE (Immunoglobulin E) Involved in allergic reactions and defense against parasitic infections. Binds to allergens and triggers histamine release from mast cells and basophils . 5) IgD (Immunoglobulin D) Found on the surface of immature B cells . Plays a role in the initiation and regulation of immune responses.

15. Serological Tests

16. Types of Serological Tests: Anti HAV ( Antibodies against the Hepatitis A virus (HAV). Anti HCV ( Antibodies against Hepatitis C Virus (HCV ). HBsAg (Hepatitis B Surface Antigen) Typhidot Widal tests (typhoid fever or enteric fever) Anti HEV (Antibodies against Hepatitis E Virus (HEV ) HIV (Human Immunodeficiency Virus) CRP ( C-Reactive Protein) RA factor ( Rheumatoid Factor) ASOT ( Rheumatoid Factor ) chronic inflammatory disorder that can affect more than just your joints

17. 1) Anti HAV : Antibodies against the Hepatitis A virus (HAV). Anti-HAV refers to antibodies against the Hepatitis A virus (HAV) . These antibodies are produced by the immune system in response to infection with HAV, which causes Hepatitis A, a liver infection.

18. There are two main types of Anti-HAV antibodies : 1) Anti-HAV IgM : Appears early in the infection and indicates an acute or recent infection with Hepatitis A. It is often used as a marker for recent exposure to HAV and usually declines after a few months as the infection resolves. 2) Anti-HAV IgG : Develops later in the infection and usually remains in the blood for life , providing immunity against future HAV infections. Its presence indicates past exposure or immunity, which can result from a previous infection or vaccination .

19. 2. Anti-HCV: Antibodies against Hepatitis C Virus (HCV). Definition : Detects antibodies against the Hepatitis C Virus (HCV). Purpose : Screens for HCV infection, indicating either past or current infection . Result Interpretation : Positive: Exposure to HCV; requires further confirmation (e.g., HCV RNA test). Negative: No exposure to HCV or during the window period .

20. 3. HBsAg (Hepatitis B Surface Antigen) Definition : Detects the surface antigen of Hepatitis B Virus (HBV) in blood. Purpose : Diagnoses acute or chronic HBV infection and monitors carrier status. Result Interpretation : Positive: Active HBV infection or carrier state. Negative: No infection.

21. 4. Typhidot Test Definition : Detects IgM and IgG antibodies against Salmonella Typhi . Purpose : Rapid test for typhoid fever diagnosis. Result Interpretation : IgM Positive: Recent or acute infection. IgG Positive: Past infection or immunity.

22. 5. Widal Test Definition : Measures antibodies (agglutinins) against Salmonella Typhi and Paratyphi antigens (O and H). Purpose : Diagnoses typhoid fever; more reliable in endemic areas. Result Interpretation : A fourfold rise in titers suggests active infection

23. 6. Anti-HEV : Antibodies against Hepatitis E Virus (HEV ). Definition : Detects antibodies against Hepatitis E Virus (HEV). Purpose : Identifies recent or past HEV infection. Result Interpretation : IgM Positive: Acute HEV infection. IgG Positive: Past infection or immunity.

24. 7. HIV (Human Immunodeficiency Virus) Test A series of tests used to detect HIV infection (the virus that causes AIDS) by identifying HIV antibodies, antigens, or the virus itself in the blood . Types of HIV Tests : Antibody Tests : Detect antibodies produced by the immune system in response to HIV infection. Most common HIV tests (e.g., ELISA , rapid HIV tests). Window Period : Can take several weeks to months after exposure for antibodies to develop . Antigen/Antibody Combination Tests : Detect both HIV antibodies and the HIV p24 antigen (a protein of the virus). Can detect HIV infection earlier than antibody-only tests . HIV Nucleic Acid Test (NAT) : Detects HIV RNA (the virus itself) in the blood. Used for early detection and to monitor viral load in HIV-positive individuals . Rapid HIV Tests : Provide results in 20 minutes or less and can be done with blood, oral fluid, or urine. Typically used in settings like clinics or outreach programs.

25. 8 . C-Reactive Protein (CRP ) Definition : Measures levels of CRP , a protein produced by the liver during inflammation . Purpose : Indicates acute or chronic inflammation . Used to monitor infections , autoimmune diseases, and heart conditions. Normal Range : <10 mg/L.

26. 9 . Rheumatoid Factor (RA Factor) Definition : Detects autoantibodies (RF) in the blood, typically associated with rheumatoid arthritis . Purpose : Helps diagnose rheumatoid arthritis and other autoimmune diseases . Normal Range : <14 IU/mL (varies by lab).

27. 10. Anti- Streptolysin O Titer (ASOT ) Definition : Measures antibodies against Streptolysin O , a toxin produced by Streptococcus pyogenes . Purpose : Diagnoses recent streptococcal infection or post-infectious complications (e.g., rheumatic fever, glomerulonephritis). Normal Range : <200 IU/mL in adults, <150 IU/mL in children.