Infection of the one-day old fertile hen's egg with rabies virus. VII. Comparison of viral yields obtained by inoculation of eggs of different ages with different strains and production of vaccine.

Abstract

Nishigahara-O30M (NOPM) strain of rabies virus, which had been produced by passing the rabbit-fixed Nishigahara strain 30 times consecutively in 1-day eggs and then transferring it to the mouse brain passage, was used to prepare the 1-day egg vaccine employing beta-propiolactone inactivation. The vaccines produced exhibited satisfactory potencies in mouse protection tests, Habel indices being consistently higher than 1,000. Preservation of the vaccine in an ice box for 4 months did not reduce the potency. A standard method of vaccine preparation suited for mass-production was also worked out. A pool of 3 lots of this vaccine was given to 30 volunteers in 3 or 4 doses of 0.1 ml. by the intradermal route with intervals of 3 to 7 days, and all the vaccinees responded to the vaccination with fairly good rises of neutralizing antibodies occurring before the end of the second week, except one person who showed only a very weak response. Little systemic reactions were observed, and local reactions appeared as erythema and induration lasting for a few days, which nevertheless became less intense upon continuation of the vaccination. It was estimated therefore that the NOPM-1-day egg vaccine might be able to replace the brain type vaccine currently used for human prophylaxis.