Abstract
A microplaque assay for morbilliviruses was developed by using carboxymethyl cellulose overlay and Vero cells, Microplaques formed by the strains of measles virus used in this experiment were distinct and easily countable with the naked eye. There was a linear relationship between the numbers of microplaques and virus concentrations. Plaque titers determined by this assay were almost the same as those obtained by the conventional macromethod. The microplaque titrations performed on measles virus were highly reproducible. The microplaque assay was applied to neutralization tests by means of the serum-dilution using a set of microdiluter and microtransfer plate. Neutralizing antibody titers against measles virus determined by this test were four times higher than those measured by the macro-CPE method and corresponded to those by the macro-plaque method. The diameters of microplaques formed by rinderpest and canine distemper viruses were 0.1 to 0.5mm and 0.1 to 0.3mm, respectively. The micro-method for the plaque titration of both viruses was shown to be less sensitive than the macro-method. It was suggested, however, that the sensitivity of the method for these viruses might be increased by improving the overlay medium.
The present technique would be applicable to other viruses by a little modification of composition of media.
