| 摘要 |
Vaccines are provided for vaccinating an animal against pathogenic bacteria, including E. coli. The invention also encompasses methods of preparing and methods of use of vaccine strains and compositions that result from or are used in these methods. In particular, pathogenic bacteria comprising at least one attenuating mutation selected from the group consisting of a pyrimidine pathway mutation, an iron metabolism mutation, and a colicin transport mutation which retain their immunogenicity so as to provide protective immunity are provided. |
