Some Experiments on the Antigenic Properties, Filterability, and Microscopy of Vaccine Virus

Abstract

Summary: Rabbits were rendered immune to subsequent vaccination by scarification when they had been given three injections of vaccine virus inactivated by any of the following methods: Heated at 60°C. for one hour. Treated with 0.1 per cent formaldehyde for twelve hours. Treated with immune serum for twelve hours, and then heated for one hour at 60°C. Heated at 60°C. for one hour, the solution centrifugated and the supernatant liquid used for injection. Intravenous, intradermal, intraperitoneal and subcutaneous injections were equally effective. Rabbits were passively immunized by the intravenous injection of serum from an animal immunized by the intravenous injection of living virus, and by the intravenous injection of serum from an animal immunized by scarification. Successful passive immunization appears to depend upon the amount of serum injected. This immunization does not appear to be due to the presence of living virus in the immune serum. The “immediate reaction” was shown by these animals as further evidence that immunity to vaccinia had been established. Normal rabbits as well as immune rabbits can tolerate the intraperitoneal injection of large doses of potent vaccine virus. No evidence was obtained that the virus existed in the filtrates from a Berkefeld (N) filter or a plaster of Paris filter. The vaccine virus was not made visible by treatment with various concentrations of acids, bases and salts or by immune serum.