TABLE 4.

Virulence of wild-type (VP161) and parent (AL435) strains and LPS mutants as determined by intramuscular challenge of 12-week-old Hy-Line Brown chickens

Strain (relevant genotype)	Dose (CFU)	Survivala
		No. surviving/total	Time (h)
VP161	1.3 × 103	0/9	14-19
AL435	1.7 × 103	0/4	14-19
AL836 (hptA)	7 × 102	9/9	NAb
AL690 (hptB)	6 × 102	0/9	16-19
AL721 (kdkA)	1 × 103	0/4	14-20

^aAll birds that reached an agreed stage of the infection were euthanatized in accordance with animal ethics requirements.

^bNA, not applicable.