Abstract
Facts that the Sendai virus has a characteristic growth curve both in a tissue culture system and in eggs, i.e. a longer latent period for a cycle growth when compared to that of the other viruses, belonging to MNI group has stimulated this work. The successful serotherapy of Sendai virus infections in mice is the subject of this communication.
The antiviral serum obtained from rabbit immunized with the chorioallantoic fluid culture of this virus was used throughout the experiment.
In order to get the uniform infections among experimental mice, preliminary studies were performed to establish the standard condition of the infection. For this purpose, 3 weeks old ddmice were choosen and the inoculum virus was atominzed. Allantoic fluid culture of mouse adapted strain was used as the seed because of its high content of complete particles, when compared to the virus of mouse lung.
Effects of time of administration and the absolute amount of immune serum on the fate of infections, were chiefly examined with two different inoculum size. In general, earlier the administration time and smaller the size of inoculum, the higher the survival rate. When the serum was given as early as 6 hrs. after infection, the amount of antibody did not show the signifficant influence on the survival rate within the limit of this experiment. But the effect of the amount of antibody was quite remarkable when the serum was given later, e. g. 12hrs. after infection. 80% of the mice infected with 3 LD50 followed by the treatment at 6 hrs. after infection survived more than 2 weeks. With this group of mice, the virus growth in lungs and the concentration of antibody in the blood stream were pursued day by day. When compared to the control mice without any treatment maximum growth of virus with treated was as low as 1/100 in the sense of EID50. Also the characteristic change of virus particles to incompletness has been noticed in the lung of treated mice.
The immune serum here used did not contain any precipitins against aqueous extract of normal mouse lung.
