For evaluating the efficacy of DNA vaccine pCAGGoptiHA5,6 groups of 3-week-old SPF chickens were intramuscular inoculated singly and boosted with 100 μg or 10 μg of pCAGGoptiHA5 in 200 μL volume.A group of chickens were injected with 200 μL PBS as controls.Sera were collected weekly after vaccination for detecting the HI,NT and AGP antibodies.Four-weeks after the single vaccination,two weeks after the boost,all chickens were challenged with 100LD_(50) of highly pathogenic A/Goose/GuangDong/1/96(H5N1)strain,...