Preliminary Study of Attenuated Japanese Encephalitis Virus.

摘要

An attenuated strain of Japanese encephalitis virus, TWN-21, was derived from the parent strain, HV-1, by 17 continuous passages in hamster diploid cell cultures and purified by isolation of a least virulent clone. The strain is characterized by low neurovirulence in suckling mice. It produces small plaques in MK2 cell culture, provokes complete cellular destruction in primary chick embryo fibroblast monolayers, and elicits high interferon titers in chick embryo fibroblasts when compared with the parent strain. The TWN-21 strain, in newborn chicks, produced low and irregular viremias; but was fully as antigenic as the parent strain. After injection into pigs, transient low grade viremias occurred in 4 of 12 animals, but the strain produced high antibody titers in all. Immunized pigs were subsequently completely protected from natural infection. (Author)