ESTABLISHMENT AND CHARACTERIZATION OF JAPANESE B-ENCEPHALITIS-VIRUS PERSISTENT INFECTION IN THE SF9 INSECT-CELL LINE

The Sf9 cell line, commonly used for gene expression by recombinant ba culoviruses, can be productively infected by Japanese B encephalitis v irus (JEV). Two wild-type JEV strains (P3 and SA14) caused a cytopathi c effect (CPE) in the Sf9 cells, while no apparent CPE was caused by a n attenuated strain (SA14-14-2). The JEV viral antigens were expressed in the infected Sf9 cells and intracellular virus particles were foun d by electron microscopy as a result of infection with all three strai ns. Titres of cell-associated and cell-free supernatant virus remained stable for relatively long periods of cultivation, suggesting that bo th wild-type and attenuated JEV strains established productive and per sistent infections of Sf9 cells. The JEV produced by the Sf9 cells cou ld be neutralized by anti-JEV reference serum, but relatively smaller plaques were formed in BHK21 cells infected with JEV that had been cul tivated long term in Sf9 cells. This system for virus propagation has a number of potentially important uses for enhancing progress in JEV s tudy and control. (C) 1996 The International Association of Biological Standardization