Standardization of methods used for testing the safety of tissue culture rabies vaccines.

Tissue culture rabies vaccines are essentially new preparations intended for prophylaxis and treatment of rabies. However, the methods used for their testing are mostly the same as those used for rabies vaccines prepared from brain tissue. Therefore, it is extremely important to develop and standardize methods for testing tissue culture rabies vaccines. The main criteria for the evaluation of Vnukovo-32 production strain have been formulated. The strain has been characterized in pathomorphological studies; the degree and nature of lesions produced in animal brain tissue by various doses of antigen and different routes of inoculation have been determined. In order to ensure the specific innocuity of rabies vaccines inactivated preparations are produced. However, with the current methods of inactivation (treatment with beta-propiolactone or phenol, ultraviolet irradiation and others) some viral particles may occasionally remain active. Besides, reparative processes may possibly occur in utraviolet-irradiated viruses. The penetration of even sublethal doses of live virus into the body is highly undesirable, since under certain conditions the long-term harbouring of the live viral particle may result in the development of various pathological conditions. In order to reveal minimum amounts of live virus in the preparation a method of additional passages in a susceptible cell system using the fluorescent antibody technique has been developed. By this method it has been possible to detect the presence of live virus in 10 out of 51 lots of vaccine under test.