Miura T
Bull World Health Organ. 1970;43(4):553-7.
The potency of Japanese encephalitis (JE) vaccine is routinely tested by intracerebral challenge of immunized mice, but since natural infection is by a peripheral route the author was led to develop a subcutaneous challenge test, using the natural route. Suckling mice 8-10 days old were immunized twice intraperitoneally with 0.15 ml of different serial dilutions of vaccine on days 1 and 4. A challenge dose of JE virus equal to 5000 intracerebral LD(50) for suckling mice was given on day 8, when the mice were not older than 19 days. The JaGAr 01 strain was used as the challenge virus, being more freshly isolated than the Nakayama strain usually employed in Japan and therefore less likely to have been modified by repeated mouse-brain passage.This new assay method should give a more accurate assessment of the effect of a vaccine which is intended to protect man from natural infection only and not from infection by an unnatural route.
日本脑炎（JE）疫苗的效力通常通过对免疫小鼠进行脑内攻毒来检测，但由于自然感染是通过外周途径，作者因此开发了一种皮下攻毒试验，采用自然途径。8 - 10日龄的乳鼠在第1天和第4天分别腹腔注射0.15 ml不同系列稀释度的疫苗，共免疫两次。在第8天，当小鼠不超过19日龄时，给予相当于乳鼠5000个脑内半数致死量（LD50）的日本脑炎病毒攻毒剂量。使用JaGAr 01株作为攻毒病毒，该毒株比日本通常使用的中山株分离得更新鲜，因此不太可能因多次在小鼠脑内传代而发生变异。这种新的检测方法应该能更准确地评估一种仅旨在保护人类免受自然感染而非非自然途径感染的疫苗的效果。
