Japanese B Encephalitis Virus: Its Differentiation from St. Louis Encephalitis Virus and Relationship to Louping Ill Virus

1. Japanese B encephalitis virus, obtained from Japanese investigators, has proved virulent for mice and monkeys, confirming the reports from Japan. It has also been found virulent for monkeys when instilled intranasally and for sheep when introduced intracerebrally or intranasally. 2. Japanese B encephalitis virus has been differentiated from St. Louis virus and found similar to louping ill virus according to its reactions in animal species. Serologically, however, it is distinct. 3. Japanese B encephalitis and its related group of primary virus encephalitides of man have been discussed with regard to their differentiation and mode of spread.