Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Detection, Quantification and Lab diagnosis Dr. Sobia Manzoor ASAB, LECTURE 4 Contents • Rationale use of the laboratory • Specimen processing • Identification of viral components Rationale use of the laboratory Viral diseases are likely to take place. Even chemotherapeutic agents are available. Advances in virology paves the way to explore new viruses or drug resistant viruses. For all this, we need to have a system where these viruses can be isolated and identified. 2. Management of the patient or prognosis is influenced by the diagnosis. 1. 3. Infections may demand public health measures. E.g. blood banks are routinely screened for HIV, HBV & HCV. Herpes simplex is easily transmittable thorough sex workers. All these information come through the effective use of lab diagnosis. 4. Surveillance of viral infections help to monitor disease prevalence, genotype dominance, history, significance as well as evaluating immunization programs. Specimen processing Collection of viral sample is a critical step in diagnosis. Identification of viral components 1. Viral isolation 2. Antigen detection 1. Immunoflourscence 2. ELISA 3. Electron microscopy 4. serology 3. Nucleic acid detection 1. Viral isolation Advances in virology greatly relies on viral propagation. Appropriate cell line, cytopathic effect (CPE) is formed. Monkey kidney cell line, human fibroblast cell line etc. Advantages Disadvantage Sensitive Slow Catch all Labor intensive Isolates Multiple cell line required Detect viable virus Antigen detection Immunoflourscence Rapid diagnostic tool. Initially undertaken with polyclonal anti-sera and then with monoclonal antibody. The method makes use of a labeled Ab. Usually its florescence. Enzyme linked immunosorbant assay (ELISA) Serological tests • Viruses generate an immune response--important serological target for diagnostics. • Serological markers are: IgG, IgM, IgE, etc. Advantages of serological tests 1. IgG----good indicator of prior infection 2. IgM---good indicator of recent infection 3. Automated 4. Rapid 5. Don’t need culturing 6. Can utilize non-invasive samples such as urine and saliva. Disadvantages of serological tests 1. In certain cases, cross reactivity. 2. Insensitive against some congenital diseases such as cytomegalovirus (CMV). 3. Not suitable for immunocompromised individuals. Nucleic acid detection PCR-Reagents DNA template Primer (F & R) MgCl2 dNTP Taqpolymerase Nuclease free water Generally, the volume of the mixture is 20µl