Abstract
The present paper describes the infectivity of RNA preparations extracted from brain of mice infected with yellow fever virus (17D strain). The infected brains were homogenized with 0.85% sodium chloride to give a 10% homogenate, which was subjected to the cold 80% phenol method by Gierer and Schramm (1956).
Infectivity of the RNA preparations assayed in 7-day-old suckling mice was approximately 10-3 of that of the original material. It was lost completely by 50μg/ml of RNA-ase within 10 minutes at 27°C, whereas DNA-ase exerted no effect; RNA-ase did not affect infectivity of the original materials. The viruses recovered from mice infected with the RNA were identified as the original yellow fever virus biologically and immunologically.
These data suggest that the infective principle in the RNA preparations is essentially the virus RNA itself.
