Table 1.

Immunization strategy for the different chicken groups.

Groups	Vaccine	Delivery vector	Plasmid content	Dose *	Route **
A	Lipofectin/ pEGFP-C1-HA2-AS	Lipofectin, 100 μL	50 μg	200 μL	i.d. 50 μL/swell
B	Phage 54/ pEGFP-C1-HA2-AS	Phage 54, 1.36×1012 pfu	1 μg	200 μL	i.d. 50 μL/swell
C	Phage 74/ pEGFP-C1-HA2-AS	Phage 74, 1.38×1012 pfu	1 μg	200 μL	i.d. 50 μL/swell
D	T7-WT/ pEGFP-C1-HA2-AS	T7-WT, 1.49×1012 pfu	1 μg	200 μL	i.d. 50 μL/swell
E	PBS	PBS	0 μg	200 μL	i.d. 50 μL/swell

* All vaccines were adjusted to 200 μL per dose. Vaccine delivered by Lipofectin contained 50 μg pEGFP-C1-HA2-AS plasmid, while vaccines delivered by phage particles contained 1 μg pEGFP-C1-HA2-AS plasmid.

** i.d. stands for intradermal injection, and multipoint injection was conducted with 50 μL/swell.