| 摘要 |
1. Live vaccine having an increased stability 2.1 The safety of bacterial live vaccines is guaranteed by deletions, the stability of which with respect to in vivo repair lying in the range of about 10-12. The high requirements of the World Health Organisation and the wide-spread opinion about the alleged instability in the use of live vaccines under practical conditions let it appear to be necessary to enhance the already existing safety buffer by yet another increase of at least the factor 10-7. 2.2 The stability of a live vaccine produced from at least one metabolic drift attenuated, immunogenic, stable single or multiple marker live vaccine with or without envelope mutation and an optimal attenuation level adapted to the sensitivity of the host species is increased by using as vaccine strain its revertant, as a suppressor mutant still having the attenuation or/and envelope markers. 2.3 Different variants of the live vaccine as well as of a special live vaccine for chickens and chicks and of their production are provided.
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