Table 1.

HI^a antibody titers in chickens immunized with pCAG-HA DNA vaccine carrying the hemagglutinin gene of avian influenza virus strain A/Hanoi/30408/2005 (H5N1)

Vaccine dose (μg)	+ Electroporation						− Electroporation
	Vaccinated birds at 56 dpvb,c			Seroconversion during course of expt			Vaccinated birds at day 56 dpv			Seroconversion during the course of expt
	Total no.	GMT	Range of endpoint titer	No. of seropositive birds/total no. of immunized	Earliest detection (avg dpv)	Antibody persistence (avg no. of days)d	Total no.	GMT	Range of endpoint titer	No. of seropositive birds/total no. of immunized	Earliest detection (avg dpv)	Antibody persistence (avg no. of days)
0	5	1	1	0/5	Not detectede	0	10	1	1	0/10	Not detectede	0
10	13	9.2	1–128	7/13	36.4	13.4	13	1	1	2/13	32.5	1
100	12	48.5	1–128	11/12	29.1	27.9	12	1	1–8	1/12	56	1
250	5	42.2	16–128	5/5	20.2	23.4	5	1	1–8	1/5	44	1

^aHI, hemagglutination inhibition.

^bdpv, days postvaccination; GMT, geometric mean titer.

^cSamples testing negative by the HI test were ascribed a titer of 1 for the purpose of calculating the GMT. An HI titer of ≥4 (i.e., 1:4) was considered positive. Endpoint dilution values were converted to log₂, and the GMT was determined and expressed as the endpoint mean titer after a reconversion.

^dThe study design allowed only for measuring antibody persistence to a maximum of 43 days before termination of the experiment.

^eNot detected indicates that none of the chickens tested positive at any of the sampling times.