1009ΔspiCΔcrp can induce humoral and cellular immune responses.
1009ΔspiCΔcrp did no harm to the chickens or produce any side effects.
1009ΔspiCΔcrp can offer efficient protection against acute systemic FT.
1009ΔspiCΔcrp can be used as a live attenuated vaccine for FT.