Rabies virus inactivation by binary ethylenimine: New method for inactivated vaccine production

Abstract

The inactivation dynamics of rabies virus (PV strain) by binary ethylenimine, and the immunogenic properties and the stability of the vaccines prepared using this agent, were studied. Binary ethylenimine at a final concentration of 0.01 M was prepared with 2-bromoethylamine hydrobromide in alkaline solutions, either separately from or in suspensions of rabies virus progagated in BHK cells. The infectivity of virus suspensions containing more than 108 plaque-forming units per 0.1 ml was inactivated in 2 h when the inactivating agent was prepared before its addition to the suspensions, and in 3 h when prepared directly in the suspensions. Liquid vaccines prepared in this manner and stored at different temperatures maintained potency for 1 month at 37°C and for 6 months at 4°C and 22 to 25°C. Lyophilized vaccine maintained its potency for 6 months at the three temperatures. The inactivated vaccine mixed with aluminum or oil adjuvant at high dilutions protected guinea pigs against challenge. This safer procedure for rabies virus inactivation offers promise for the production of effective vaccines for the immunization of dogs and cattle.