The second revived strain of culture vaccine virus has been propagated through 130 culture passages during a period of 3 years. It seems to be adapted to in vitro cultivation and still has an intradermal titer (rabbits) of 1 to 100,000 or 1 to 1,000,000.
Intradermal inoculations in human beings of 0.1 cc. amounts of culture virus diluted from 2.5 to 10 times result in primary takes in unvaccinated people and immune reactions or accelerated takes in individuals previously successfully vaccinated. Primary takes produce an immunity to standard strains of calf lymph.
Culture virus mixed with purified gum acacia (2.5 per cent), frozen, desiccated, and sealed in vacuo retains its activity for a month at 37°C., and when the dried virus is resuspended in saline solution it is suitable for intradermal vaccination of human beings.