Abstract
Summary
The virus of influenza grown in allantoic fluid of chick embryos can be pre-cipitated in a stable form with alum and the precipitate redissolved in sodium citrate. This procedure does not alter the infective, anti-genic, or hemagglutinating properties of the virus. Adsorption on sterile chicken cells was also used to concentrate the virus before inactivation and precipitation with alum.
The immunizing power of formalinized and alum-precipitated virus in mice was slightlv less than that of active fluid. Inactive con-centrated alum precipitates inoculated sub-cutaneously produced a satisfactory antibodv response in human beings. The suspensions of alum precipitates freed of formaldehyde and acid retain their antigenicity when stored at 4°C for at least three months.
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