Attenuation of rubella virus by serial passage in primary rabbit kidney cell cultures II. Experiments in animals

Summary

The primary rabbit kidney cell propagated Cendehill strain of rubella virus was studied in vivo at different passage levels. The low passage levels consistently evoked significant amounts of antibodies in parenterally inoculated rabbits and monkeys. At the higher passage levels, however, the virus completely lost its immunogenicity for rabbits. A similar phenomenon was observed in monkeys. Following intramuscular inoculation of 51st passage virus a high percentage of monkeys failed to develop any detectable antibodies, as measured by serum-neutralization or hemagglutination inhibition techniques. None of the monkeys inoculated by the intranasal route with virus from the same passage level showed any serologic response.

This rubella virus strain, which has been markedly modified in its biological properties for monkeys and rabbits, still proved highly immunogenic in vaccinated children.