Main Factors Influencing the Efficient Propagation of Virulent or Attenuated Strains of Japanese encephalitis virus in BHK-21 Cells.

Japanese encephalitis virus (JEV) causes severe viral encephalitis in humans and some other mammalian animals. Highly efficient culture of the virus is critical for antigen preparation, vaccine production and other basic researches. We have investigated the influence of a number of variables such as the strain virulence, the state of the host cells, medium composition, infection method and others on the proliferation of distinct JEV strains in BHK-21 cells. The results showed that two distinct strategies are needed for the propagation of virulent or attenuated JEV strains. The most critical variables were the method of infection, and especially the density of the host cell. Our studies indicate the general approaches to the in vitro culture of other JEV strains using BHK-21 cell line.