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.

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A potent toxin was produced by a strain of Clostridium perfringens PB6K in a chemically defined medium consisting of 19 amino acids, fructose, vitamins and minerals. A large amount of L-arginine (10 mg/ml or higher concentration) was required for toxin production. An excess of L-cystine (0.1 mg/ml or higher) reduced the yield of toxin seriously. Zinc and manganese, though ineffective for growth, were necessary for satisfactory production of toxin. Although magnesium and iron were indispensable for growth, their excesses were deleterious for this organism ; the harmful effects were more prominent for toxin production than for growth.

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The ovicidal activity of thiabendazole on helminth eggs in water and in nightsoil was examined by cultivation of these eggs after exposure to the drug. Embryonation of Ascaris eggs in both acid and alkaline buffered solutions was consistently inhibited at the concentration of 1.56 ppm in a 7-day exposure at 25C. The minimal effective concentrations of thiabendazole on Ascaris eggs in nightsoil at 5C, 15C and 25C were 400, 100 and 6.25 ppm, respectively, in a 3-day exposure, and 200, 25 and 3.12 ppm, respectively, in a 7-day exposure, while on Trichuris eggs they were 25, 6.25 and 1.56 ppm, respectively, in a 3-day exposure, and 12.5, 3.12 and 0.39 ppm, respectively, in a 7-day exposure. The minimal effective concentrations of thiabendazole on hookworm eggs in nightsoil were 1.56 and 0.78 ppm in both 3-day and 7-day exposures, respectively, at the exposure temperature of 15C. Pre-field test on the ovicidal effect of thiabendazole on the helminth eggs in nightsoil was carried out employing nightsoil tanks which contained different volumes of nightsoil ranging from 140 to 650 liters. Ascaris and Trichuris eggs were killed by thiabendazole at a concentration of approximately 50 ppm and hookworm eggs at a concentration of approximately 5 ppm after a 7-day exposure.

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