Consequences of active or passive immunization of turkeys against Escherichia coli O78

Turkeys were injected at 7 and 14 days of age with live, heat-killed or formalin-killed Escherichia coli O78. Other turkeys were passively immunized at 22 days of age with hyperimmune serum produced against live or heat-killed E. coli O78. All turkeys were challenged at 24 days of age with E. coli O78. Turkeys immunized intramuscularly or intratracheally with live E. coli O78 were protected from death, whereas few turkeys given killed E. coli O78 were protected. Passively immunized turkeys were protected from death regardless of whether live or heat-killed E. coli O78 was used to produce the hyperimmune serum. Most turkeys that survived challenge developed septic polysynovitis 2--4 days after challenge.