INFECTIOUS, HEMAGGLUTINATING, AND COMPLEMENT-FIXING COMPONENTS IN SUCKLING MOUSE BRAINS INFECTED WITH JAPANESE ENCEPHALITIS VIRUS

Abstract

Two infectious, 3 hemagglutinating (HA), and at least 3 complement-fixing (CF) fractions could be detected in the pattern obtained by sucrose density gradient centrifugation of partially purified H3-labeled Japanese encephalitis virus (JE virus) preparation from suckling mouse brains infected with each of Nakayama, JaGAr-01, and JaTh-160 strains. The patterns of those fractions are apparently the same in the 3 strains used, but somewhat different quantitatively and qualitatively in each fraction. One infectious fraction was discerned to be composed of a complete spherical virus of 40-50mμ in size, associated with both the viral HA and CF activities, and the other was smaller one remaining in a top fraction, having also some of HA and CF components. No marked difference was recognized in plaque size formed on chick embryo monolayer or in pathogenicity for adult mice between the viral and top infectious components, except that the latter component was, to some extent, resistant to inactivation by immune serum as compared with the former. No incorporation of H3-uridine or cytidine, nucleic acid precursor, into any of the noninfectious HA and CF components in the preparation of JaGAr-01 strain suggests that those components are likely to be a precursor or incomplete virus particles lacking the inner nucleic acid. The top HA component “floating” in the sucrose density gradient centrifugation was found to be stable at a raised temperature or in a mechanical treatment, but the viral and noninfectious HA components were not. Each HA component has its own narrow optimum of pH dependency shifting to a little more acidic than that of crude HA antigen.