| Understanding the distribution of avian influenza virus in Guangzhou city,the investigation carried out. According to the principle of random sampling, 12 farmers market were selected to sample 2880 copies during 12 months in district Baiyun and Panyu. For the evaluation of recombinant avian influenza virus inactivated vaccine(H5N1 subtype, Re-6 strain) and avian influenza inactivated vaccine(H5N2 subtype, D7 strain) on the immune effect to duck, 300 white ducks and 240 muscovy ducks were divided into 4 groups respectively, immunized with H5N2 D7 or H5N1 Re-6 inactivated vaccine with given immunization program and raised in normal way. Serum samples were collected from each group each week,lasted for two weeks, after immunization till the time for marketing, and the hemagglutinin inhibition(HI) antibody was detected.Results show as follow:Universal flu positive rate was 78.02%. Flu positive rate determined with swab stick for waterfowl was highest, and reached 92.05%, and that of environment, chick and other poultry tested with Cotton swab were 85.92%, 78.87% and 54.32%respectively. The result of investigation indicated serious pollution situation of bird flu showed in live poultry farmers’ market of Guangzhou.In the day 10, the maternal antibody titer of white ducks and muscovy ducks were 3.02 log2 and 0 log2 respectively. The time for first immunization for ducks may need further study. At the day 14 after the first immunization, the HI titers of H5N2D7 vaccine groups was higher than that of H5N1 Re-6vaccine group both in white ducks and muscovy ducks. The HI titers of two kinds of vaccines were all higher than4 log2, and reached the qualified rates by ≥ 70% both for white ducks and muscovy ducks at 3-5 weeks after the first immunization. Since 1 week after the secondimmunization till birds coming to market, the two vaccines presented a good immune effect with antibodies HI titer by > 7 log2 and qualified rates ≥ 80% in the two kinds of ducks. Besides, Antigen subtypes of HI affected the effect of antibody detection.This study conclude that there were good response in the two kind of vaccines, the H5N2 vaccine(D7 stain) was more suitable for ducks and may play more important role for prevention and controlling of virus in waterfowl in China. |
