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INTRODUCTION IN THE past few years several effective infectious bronchitis virus vaccines have become available. These vaccines given at the proper time and under proper conditions usually give adequate protection through the first production year. Unfortunately, they all contain live viruses and exhibit the following limitations: (1) a spread of the virus to susceptible flocks in the area, (2) a vaccine reaction which might serve as a stress factor predisposing the birds to other infections, especially respiratory infections, (3) a depression of egg production, (4) possible contamination with other pathogens. The classical physical and chemical virus inactivating agents have not been effective when applied to IBV. These agents (phenol, formalin, ultraviolet irradiation, etc.) destroy the antigenicity of the virus as well as the pathogenicity. Recently a new compound, beta-propiolactone (BPL), has been reported for sterilization of blood plasma and for the inactivation of viruses (Hartman et al., 1951, 1954). Mack . . . |
