Efficacy of a temperature-sensitive Sendai virus vaccine in hamsters

A temperature-sensitive HVJ-pB strain of parainfluenza type 1 (Sendai) virus was obtained from a persistently virus-infected cell culture. Intranasal inoculation of Syrian hamsters with the HVJ-pB temperature-sensitive mutant resulted in an abortive infection but induced a specific antibody response against Sendai virus without appreciable lesions in the respiratory tract. Prior exposure to the temperature-sensitive mutant protected hamsters from subsequent challenge with virulent wild-type virus. The efficacy of protection became apparent at 5 days after vaccination and lasted for at least 720 days. For practical use of the HVJ-pB vaccine, a single intranasal administration to newborn babies aged over 15 days is recommended.