| Popis: |
THE importance of avian embryos in the cultivation of some viruses and production of vaccines is widely known. Embryo mortality and growth rate are vital factors in the quality and volume of vaccine produced. Yet the sporadic nature of the demand for vaccines plus the limited time they can be stored has not encouraged biological laboratories in establishing specialized strains of chickens. For example, the summer of 1957 witnessed a period of huge demand for fertilized chicken eggs for the mass cultivation of the new Asiatic influenza virus. Biological manufacturers during this period purchased most, if not all, of the available fertilized eggs which the poultry industry could produce in the short run. Since the completion of this study, the need has arisen for the use of eggs of special strains of chickens free from leucosis viruses in the production and testing of measles vaccine. While much effort goes into… |
