An in vitro virus infectivity assay based on the newly introduced spectrochemical method was performed using Peste des Petits Ruminants (PPR) virus infected Vero cell line as a model infection. Herein, the mitochondrial reductase enzyme activity was monitored using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reagent as a substrate which was reduced to a insoluble formazan products. The purple to darker color was achieved upon hydrolysis of the insoluble formazan with DMSO solution. The absorbance (OD values) of colored solution was measured by spectrophotometer at a wave length of 570nm. The infectivity/viability data were achieved from the OD values of different doses of virus infected or non-infected cells using the standard formulae. The OD values obtained from spectrochemical assay were compared with traditional Plaque assay and validated with Trypan blue assay. The data obtained from spectrochemical analysis showed similar trend as was achieved with traditional methods with a little variation in the sensitivity. The sensitivity variations are obvious due to the marked differences in the measurement unit and detection methods. However the newly introduced spectrochemical method showed superiority over the traditional methods because of its simple, label free, less time consuming measurement method and its suitability in the monitoring of large number samples.
Key words: Spectrochemical-Assay, PPR virus, MTT assay, Plaque assay, Trypan blue assay
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