Fig. 9.

HI antibody titers against AIV H5N1 in chickens vaccinated with DEV-H5(UL55). A total of 50 3-week-old commercial chickens were randomly divided into five groups of A-AI(3C), B-AI(3C), C-AI(3C), D-AI(3C), and E-AI(3C). In groups A-AI(3C), B-AI(3C), and C-AI(3C), chickens were vaccinated intramuscularly with DEV-H5(UL55) at a dose of 1 × 10⁷ TCID₅₀ (Line: 10⁷), 1 × 10⁶ TCID₅₀ (Line: 10⁶), and 1 × 10⁵ TCID₅₀ (Line: 10⁵), respectively. Chickens in group D-AI(3C) were inoculated subcutaneously with a dose of 0.3 ml of inactivated AIV H5N1 Re-6 vaccine (QYH) according to the manufacturer’s instructions (Line: Re-6). Chickens in the control group E-AI(3C) were inoculated with 0.2 ml of PBS (Line: Control). Serum samples of all chickens were collected before inoculation and at 1, 2, 3, 4, 5, and 6 weeks after vaccination to measure the HI titers, which are shown here