Table 1. Design of the trial.

Groups	Different products of killed SE PTs	Administration with killed SE PTs or undergoing pathogenic SE PT 6A	Chicks’ numbers sacrificed on certain days postadministration
			D0	D14	D21	D28
CV635	Killed SE PT 6A, 3A and 35	Administered with killed SE PT but no pathogenic dose of SE PT 6A	0	4	4	4
CV635C	killed SE PT 6A, 3A and 35	administered with killed SE PT then pathogenic dose of SE PT 6A	0	0	4	4
CV671	killed SE PT 6A, 7 and 1	administered with killed SE PT but no pathogenic dose of SE PT 6A	0	4	4	4
CV671C	killed SE PT 6A, 7 and 1	administered with killed SE PT then pathogenic dose of SE PT 6A	0	0	4	4
CV673	killed SE PT 6A, 7 and 3A	administered with killed SE PT but no pathogenic dose of SE PT 6A	0	4	4	4
CV673C	killed SE PT 6A, 7 and 3A	administered with killed SE PT then pathogenic dose of SE PT 6A	0	0	4	4
CV675	killed SE PT 6A, 7 and 35	administered with killed SE PT but no pathogenic dose of SE PT 6A	0	4	4	4
CV675C	killed SE PT6A, 7 and 35	administered with killed SE PT then pathogenic dose of SE PT 6A	0	0	4	4
CV613	killed SE PT 6A, 1 and 3A	administered with killed SE PT but no pathogenic dose of SE PT 6A	0	4	4	4
CV613C	killed SE PT 6A, 1 and 3A	administered with killed SE PT then pathogenic dose of SE PT 6A	0	0	4	4
CVZ	Control	administered with killed SE PT but no pathogenic dose of SE PT 6A	4	4	4	4
CVZC	Control	Non- administered with killed SE PT and no pathogenic dose of SE PT 6A	0	0	4	4