Infectious Ribonucleic Acid of Japanese B Encephalitis Virus: Optimal Conditions for Its Extraction and for Plaque Formation in Chick Embryo Cell Monolayers, and Some Biologic Properties

Abstract

Optimal conditions for obtaining infectious RNA from mouse brains infected with JBE virus were three phenol extractions followed by more than three ether treatments for removing the excess phenol contained in the aqueous phase. Maximum number of plaques in chick embryo cell monolayers were formed either when the RNA preparation was diluted in 1.0 M NaCl solution, or when the cell layer was washed with 1.0 M NaCl solution prior to seeding with the RNA preparation. RNA required approximately 5 to 10 minutes to initiate maximum infection of chick embryo cell cultures. RNA was quite stable to acid compared to intact JBE virus, and was about as sensitive to heat as intact virus. Ether, chloroform, and n-butanol had no influence on the infectivity of JBE RNA, whereas the intact virus was promptly inactivated by these reagents. RNA was much more resistant to sodium desoxycholate than was intact virus.