A spontaneous temperature sensitive mutant of Japanese encephalitis virus: Preliminary characterization

Abstract

Summary A spontaneously arising temperature sensitive (ts) mutant of Japanese encephalitis virus (JEV),ts 104, was isolated from chick fibroblast (CF) cell cultures of JEV strain M1/311. Straints 104 was plaque purified and characterized to ascertain its potential as a candidate for a live vaccine. Parameters of its growth, temperature lability, immunogenicity and virulence were examined.Ts 104 has been shown to be a stablets JEV strain, multiplying as well as the parent strain in CF cultures at 35° C, but not multiplying at 39° C. It was avirulent for embryonated chicken eggs incubated at 39° C and of reduced virulence for intracerebrally (i. c.) inoculated mice as measured by LD₅₀ in weanling mice and average day of death in weanling and suckling mice. Intraperitoneal injection of adult mice with either parent orts strain resulted in similar levels of protection against challenge with either strain. The potential ofts 104 as a candidate live JEV vaccine strain is discussed.