マウスの日本脳炎ウイルス感受性におよぼす加齢の影響

抄録

In the ICR-JCL strain of mice, the influence of age on the susceptibility of mice to JE virus infection by intravenous route was investigated.
The mortality rate was the highest in suckling mice, and almost no mice survived. More than 60% of them died with severe intestinal hemorrhage.
In mice aged over 21 days, the mortality rate decreased, and it was within the same level in a group of mice of the same age, independent of the dose of virus administered in the range between 5 and 5×10⁶ smic LD₅₀. The rate of intestinal hemorrhage also decreased with age. More than 90% of the mice that survived age 21-180 days developped HI antibody 3 weeks after infection. The mortality rate was higher in the male mice of age 36-180 days. On the contrary, it was higher in female mice over 180 days of age.
Some of the mice infected with such symptoms, including severe loss of body weight, recovered and survived for more than 3 weeks. Among 45 sick mice of age 61-210 days, 9mice(20%) recovered.
Mice over 180 days of age, showed the lowest mortality rate of about 20 (male) and 30% (female) respectively. HI positive rate of the mice that survived was also the lowest (less than 80%) at this age.
In mice over 365 days of age, the mortality rate significantly increased as well as the HI positive rate of those that survived. And 96% of the mice that survived over 550 days of age showed a positive HI rate.
The results may imply that the higher mortality rate of mice by JE virus infection could be related to the ability of higher antibody response in young as well as in very aged animals.