Assay Method Information

Assay Name:  n vitro cytoprotection assay
Description:  HEp-2 cells, (originally derived from tumors grown in irradiated-cortisonised weanling rats that had been injected with epidermoid carcinoma tissue from a 56 year old male's larynx, but later found to be indistinguishable from HeLa cells by PCR DNA analysis), were used for the culturing of genotype A, Long strain RSV. Flasks were inoculated with RSV and viral stocks were collected once cytopathic effect (CPE) was greater than 90%. Viral stocks in 25% sucrose media were snap frozen using liquid nitrogen to increase viral stability. Viral stock titers were quantified by tissue culture infectious dose 50% (TCID50) using 8,000 cells per well and 3-fold viral dilutions across a 96-well plate, cultured for 4 days.Following extensive parameter testing, the final assay is run as follows: HEp-2 cells are seeded into the inner 60 wells of a 96-well plate at 8,000 cells per well in a volume of 50 using Growth Media (DMEM without phenol red, 1% L-Glut, 1% Penn/Strep, 1% nonessential amino acids, 10% FBS). 2-fold serial dilutions of control and test compounds are added to the wells in duplicate in a total volume of 25 μL. Viral stock is then added to the wells in a volume of 25 μL, bringing the total volume of each well to 100 μL. Each 96-well plate has a control column of 6 wells with cells and virus but no compound (negative control, max CPE), a column with cells but no compound or virus (positive control, minimum CPE), and a column with no cells or virus or compound (background plate/reagent control). The control wells with cells but no virus are given an additional 25 uL of growth media containing an equal quantity of sucrose as those wells receiving the viral stock in order to keep consistent in media and volume conditions. The outer wells of the plate are filled with 125 μL of growth media to act as a thermal and evaporative moat around the test wells. Following a 4-day incubation period, the plates are read using ATPlite (50 uL added per well), which quantifies the amount of ATP (a measure of cell health) present in each well. Assay plates are read using the Envision luminometer.
Affinity data for this assay
 

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