Table 2.

Protective efficacy of S06004ΔSPI2. Group A and C were intramuscularly immunized with 2 × 10⁷ CFU S06004ΔSPI2 in 2-day old chickens, group B, D and E were nonimmunized. At 10 dpv, group A–D were challenged

Group	Vaccination	Number	Challenge			Survivors/Total	Survival rate (%)
	Strain		Strain	Route	Dose (CFU)
A	S06004△SPI2	10	S06004	intramuscularly	2 × 109	9/10	90*
B	PBS	10	S06004	intramuscularly	2 × 109	1/10	10
C	S06004△SPI2	10	SG9	intramuscularly	2 × 109	7/10	70*
D	PBS	10	SG9	intramuscularly	2 × 109	0/10	0
E	PBS	10	—	—	—	10/10	100

*P < 0.05 for comparison of group A with group B, and group C with group D