Analysis Infectivity and Titer Determination of Viruses and Viral vectors of Biopharmaceutical Compounds by Virus Titration / TCID50 Assay (CAT#: STEM-B-0385-CJ)

Name: Analysis Infectivity and Titer Determination of Viruses and Viral vectors of Biopharmaceutical Compounds by Virus Titration / TCID50 Assay
SKU: STEM-B-0385-CJ
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Introduction

Biological activity is, besides the safety of the therapy, the most important aspect of a drug product or therapy. Thus, a major goal of formulation development is to maintain the functionality of the therapeutic compound inside its formulation throughout its shelf-life.

Functional titer, also known as infectious titer, is the measurement of how much virus actually infects a target cell. Functional titer may be expressed in the form of transduction units per mL (TU/mL), plaque-forming units per mL (pfu/mL), or infectious units per mL (ifu/mL), depending on the viral vector.

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Principle Applications Procedure Materials

Principle

The number of infectious virus particles is frequently quantified by using the Median Tissue Culture Infectious Dose (TCID50) assay. The assay works by adding a serial dilution of the virus sample to cells in a 96 well plate format. The type of cell is specifically selected to show a cytopathic effect (CPE), i.e. morphological changes upon infection with the virus or cell death. After an incubation period, the cells are inspected for CPE or cell death and each well is classified as infected or not infected. Colorimetric or fluorometric readouts are also possible, which can increase assay sensitivity. The dilution, at which 50% of the wells show a CPE, is used to calculate the TCID50 of the virus sample. This calculation can generally be done by a variety of mathematical approaches, e.g., the Spearman-Karber method or the Reed-Muench method. Virus titer is expressed as TCID50 / ml.