| natural and experimental infections of japanese tree sparrows with japanese encephalitis virus. | 20 to 37 per cent of wild japanese tree sparrows had neutralizing antibodies to japanese encephalitis virus (jev). sparrows free of antibodies were inoculated with 10,000 plaque-forming units of jev. none of the birds became clinically ill. virus could be detected in blood plasma during the first 3 days after inoculation but not thereafter. neutralizing antibodies started to appear at 4 days after inoculation and the response was of variable duration, in some cases extending up to 200 days after ... | 1975 | 174531 |