ASSAY OF VIRAL PARTICLES. PRESENTED BY IDOWU TEMITAYO .O. MATRIC NUMBER: 0903010024 DEPARTMENT OF BIOLOGICAL SCIENCES, COLLEGE OF NATURAL SCIENCES,JOSEPH AYO BABALOLA UNIVERSITY, IKEJI-ARAKEJI, OSUN STATE.
OUTLINEDEFINITION OF TERM.VIRAL GROWTH RECOGNITION.COMMONLY USED LABORATORY METHODS FOR THE DETECTION OF VIRUSES.QUANTIFICATION OF VIRUSES.TRADITIONAL METHODS.MODERN METHODS.CONCLUSION.
DEFINITION OF TERMSWHAT ARE VIRUSES?“A PIECE OF BAD NEWS WRAPPED UP IN A PROTEIN”WHAT IS AN ASSAY?ASSAY IS AN INVESTIGATIVE (ANALYTIC) PROCEDURE IN LABORATORY MEDICINE, MICROBIOLOGY, ENVIRONMENTAL BIOLOGY, AND MOLECULAR BIOLOGY FOR QUANTITATIVE ASSESSING OR QUALITATIVELY MEASURING THE PRESENCE OR AMOUNT OR THE FUNCTIONAL ACTIVITY OF A TARGET ENTITY (Mckean et al., 2005).
VIRAL GROWTH RECOGNITION.Recognition of a diseased stateSystemic infection.The production of a local lesion such as plaque.In tissue culture the culture will undergochange with the production of cytopathiceffect (CPE), namely the destruction of thecell, syncytia formation, or cellulartransformation.
Plate 1: CYTOPATHIC EFFECT (CPE)Source: Wikipedia
COMMONLY USED LABORATORY METHODS FOR THE DETECTION OF VIRUSES.Measure of virus infectivity.Examination of viral serology (that is, host antibody responses to the virus).Molecular methods.
QUANTIFICATION OF VIRUSES• TRADITIONAL METHOD-: These are industry standard methods that have been used for decades but are generally slow and labour intensive.• MODERN METHOD-: These are relatively new commercially available product and kits that greatly reduce quantification time.
50% TISSUE CULTURE INFECTIVE DOSE (TCID50)This endpoint dilution assay quantifies the amount of virus required to kill 50% of infected hosts or to produce a cytopathic effect in 50% of inoculated tissue culture cells.
PROTEIN ASSAY:There are several variations of protein- based virus quantification assays.In general, these methods quantify either the amount of all protein or the amount of a specific virus protein in the sample rather than the number of infected cells or virus particles.
HEMAGGLUTINATION ASSAY:The hemagglutination assay (HA) is a common non-fluorescence protein quantification assay specific for influenza. SINGLE RADIAL IMMUNODIFFUSION ASSAY:Single Radial Immunodiffusion Assay, also known as the Mancini method, is a protein assay that detects the amount of specific viral antigen by immunodiffusion in a semi-solid medium (e.g. agar).
Flow cytometry: MODERN METHODS: A virus counter quantifies the number of intact virus particles in a sample using fluorescence to detect proteins and nucleic acids.Quantitative Polymerase Chain Reaction (qPCR):Quantitative PCR utilizes polymerase chain reaction chemistry to amplify viral DNA or RNA to produce high enough concentrations for detection and quantification by fluorescence.
Enzyme-Linked Immunosorbent Assay (ELISA): ELISA is a more modern variation of a protein assay that utilizes a specific antibody linked to an enzyme to detect the presence of an unknown amount of antigen (i.e. virus) in a sample.
CONCLUSIONA basic principal of science ismeasurement or quantitation,therefore being able to accuratelyquantify virus numbers became anecessity.