Abstract
1. In the spring, 1954, there was an outbreak of so-called “mouse-influenza” at A institute in Tokyo, and in 1956, there was another outbreak of the same disease at B institute in Kanagawa prefecture. Four strains of Myxovirus para-influenzae 1 (HVJ) were isolated from the lung of four groups of the mice at B institute. Three-weeks-mice inoculated intranasally showed clear “mouseinfluenza” symptoms and all of them died between 2 to 7 days.
In the autumn, 1954, the same virus, once more, was isolated from the lung of two infant guinea-pigs produced in Gifu prefecture. Hemorrhagic lesion, edema and bronchial catarrh were observed in the lung.
2. During the period from April to October, 1954, the sera were collected from the market-mice in Chiba, Saitama, Tokyo and Shizuoka prefectures and the mice of in inbred-strain at six institutes in many districts of Japan. The positive high titers of H. I, C. F and neutralizing antibody for para-influenza 1 virus were observed in the some of the sera. It was supposed that the virus may be wildly prevalent among the mouse population in that year.
3. It was observed that the mice-passaged-virus shows the viscerotrope character, while the egg-passaged-virus shows the pneumotrope character in accordance with the results examined on the D D M strain.
