Plaque assay method for vaccinia virus: accuracy and its mathematical model

Titrating infective virus by plaque assay is one of the most accurate methods which could determind the numbers of infective virus. The result shows that a considerable number of vaccinia viruses in inoculum were still unadsorbed to cv - 1 cell monolayer after a period of 4 hours adsorption time. A reciprocal and unlinear relationship between the titer of virus and the volume of inoculum, the volume of liquid medium was detected. According to this relationship, several new plaque assay methods, which had the advantage over routine method, were designed. By means of electronic computer equipped with mathematical software package, the curve fitting model and the surface fitting model of titer with the volume of virus inoculum and the volume of medium had been established. By curve fitting model, the extrapolated value of vaccinia virus titers was obtained five fold higher than the titers by routine method.