An efficient method for production of purified inactivated Japanese encephalitis vaccine from mouse brains.

The efficiency of production of purified Japanese encephalitis (JE) vaccine from mouse brains was increased by reprocessing the brain material after recovery of the virus and by pooling of a few extra fractions after zonal ultracentrifugation. By the routine production method, one mouse yielded approximately 2.5 doses of the vaccine while the improved method gave about five doses from each mouse. All the batches of purified JE vaccine made by improved technology passed all the quality control tests as specified by the Minimum Requirements for biological products of the Japanese Government and World Health Organization.