リフトバレー熱ウイルス向神経性株の向汎性株にたいする干渉

Abstract

The interference o f the neurotropic strain with the pantropic strain of Rift Valley fever virus was studied in mice.1. Neurotropic virus, when inoculated intraperitoneally, interfered with intraperitoneal infection of pantropic virus and a decrease in mortality rate and a prolongation of the death-time were observed.2. Neurotropic virus of 107-8×LD50 was necessary to interfere with pantropic virus of 103×LD50.3. When pantropic virus was inoculated 24 hours before neurotropic virus, the interference did not occur. Pantropic virus inoculated simultaneously with or immediately after neurotropic virus was interfered.When pantropic virus was inoculated thereafter, the interference gradually changed to the immunity without any definite border-line separating them.4. Neurotropic virus inoculated intraperitoneally interfered with pantropic virus inoculated intraperitoneally, subcutaneously, intravenously or intracerebrally. When inoculated subcutaneously, neurotropic virus slightly interfered with pantropic virus inoculated subcutaneously at a different site, but not with pantropic virus inoculated intraperitoneally, intravenously or intracerebrally.5. When the interference occured, the multiplication of pantropic virus was strongly inhibited. But effect on the multiplication of neurotropic virus could not be determined. When the multiplication of pantropic virus was sufficiently inhibited, some of the mice died of infection of the brain with neurotropic virus and the remaining mice survived, as observed in mice inoculated with neurotropic virus alone. Or, some animal died of infection of the brain with pantropic virus. When the multiplication of pantropic virus was not sufficiently inhibited, the animal died of systemic infection with this virus, but the deathtime was somewhat prolonged.6. Emulsions of normal mouse brains had not interfering activity. When mouse brain emulsions infected with neurotropic virus were centrifuged at high speed, the resulting sediment containing most of the infectivity of the original material demonstrated the interfering activity, while the supernatant did not. These findings support that the virus particle is the interfering agent.7. Neurotropic virus inactivated by ultraviolet irradiation interfered with pantropic virus.On the bases of these findings, the behavior of neurotropic virus in the extraneural organs was discussed and the possibility was suggested that there might be an infection process in which the virus can not complete the multiplication process to produce mature virus, but inhibit the multiplication of superinfected pantropic virus.