1 / 18

Diagnosis of viral diseases

Diagnosis of viral diseases. Diagnosis of viral diseases. Three General Approaches for Laboratory Diagnosis of Viral Infections : Direct detection -Microscopy or staining. Virus Isolation -PCR. Serology -Antibodies. Viral Serology. Detection of SPECIFIC antibodies.

abel
Download Presentation

Diagnosis of viral diseases

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Diagnosis of viral diseases

  2. Diagnosis of viral diseases Three General Approaches for Laboratory Diagnosis of Viral Infections : Direct detection -Microscopy or staining. Virus Isolation -PCR. Serology -Antibodies .

  3. Viral Serology • Detection of SPECIFIC antibodies. • Indirect : Primary and secondary responses to viral infections • IgM antibody during acute phase (1st exposure) • IgG antibody during convalescence (2nd exposure) • IgA mucosal antibody (respiratory infections, GI)

  4. Serology Tests • Serology Tests Commonly Used : • Haemagglutination. • Haemagglutination Inhibition. • Complement fixation. • Indirect Fluorescent Assay (IFA). • Indirect EIA (ELISA).

  5. Viral Serology • Indirect Fluorescent Assay (IFA) • Indirect EIA (ELISA)

  6. Viral Serology • Enzyme-Linked Immunosorbent Assays (ELISAs) : • Enzyme-Linked ImmunoSorbent Assay, or ELISA, is a biochemical technique used mainly in immunology to detect the presence of an antibody or an antigen in a sample. The ELISA has been used as a diagnostic tool in medicine • Enzyme reacts with substrate to produce colored product . • Very sensitive . • Not expensive.

  7. ELISA Procedures

  8. Advantages of Viral serology : 􀂃 • Determine immune status – person or population • Verify immune response to vaccination • Diagnosis of chronic infection/ reactivation ? • Diagnosis of recent infection ? (IgM & IgA) • Wide range of tests available • Uses serum – easily collected and transported • (compared with biopsy tissue or DNA )

  9. Viral markers • Some common viral markers detected by serology : • HAV • HBV • HCV • CMV • OTHERS

  10. HEPATITIS A • Serology: • Acute – IgM – lasts 3-6 months . • Chronic – IgG – lifetime . • Liver enzymes – increases in ALT, AST, bilirubin

  11. EVENTS IN HEPATITIS A VIRUS INFECTION Clinical illness Infection ALT IgM IgG Viremia Response HAV in stool 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Week

  12. HEPATITIS B • Serology: - acute: • HBsAg+ (HBsAb-) = acute infection or chronic carrier • HBeAg+ = highly infectious • HBsAb = immune – naturally or vaccine • Window phase = HBsAg- and HBsAb- will be HBcAb+ (IgM – acute)

  13. HEPATITIS C • ss +RNA Flavivirus (former non-A, non-B) • Marked genetic heterogeneity due to hypervariable region • Mutates under immunologic pressure and becomes chronic • Vaccines are difficult to develop • Immunoglobulin not effective

  14. Serologic Pattern of Acute HCV Infection with Recovery anti-HCV Symptoms +/- HCV RNA Titer ALT Normal 6 1 2 3 4 0 1 2 3 4 5 Years Months Time after Exposure

  15. EBV Serology • EBV VCA IgG: Positive • EBV VCA IgM: Positive • EBNA IgG: Negative • EBV AI: <60% • Acute EBV 􀂄􀂄

  16. THANK YOU

More Related