摘要 |
<p>A vaccine for the immunization of domestic fowl, such as turkeys and chickens, against E. coli infections (Colibacillosis) is disclosed which contains an effective amount of a live temperature sensitive mutant of E. coli dispersed in a physiologically acceptable, non-toxic liquid vehicle. The E. coli mutant disclosed exhibits growth at 32 °C but not at 41 °C and has a reversion frequency of less than about 1 x 10-8.</p> |