ON LABORATORY CRITERIA FOR ASSESSMENT OF THE SAFETY OF STRAIN CANDIDATES FOR LIVE VACCINE AGAINST TICKBORNE ENCEPHALITIS

Analysis of published data on improvement of laboratory criteria of sa fety of strain candidates for live vaccine against rick borne encephal itis (TEE) showed that all the proposals imply more rigid requirements to the level of viral neurovirulence for mice and Syrian hamsters and regulation of in vitro biological properties of the strains. Species specificity of attenuation and absence of a close correlation of TEE c omplex viruses neurovirulence with their in vitro biological propertie s make these proposals useless, similarity of poliomyelitis and TEE in the principal clinical and pathomorphological manifestations of the n eural phase of infection is sufficient for theoretical validation of t he permissible level of neurovirulence of candidate strains for live a nti-TEE vaccine after Sabin's vaccine strain prototype. Different auth ors prepared attenuated variants. of Langat TR-21 Malayan virus apatho genic for monkeys as shown by clinical data. At present it is desirabl e to compare these and other similar strains with Sabin's vaccine stra ins by neurovirulence for monkeys by pathomorphological data.