Detection And Analysis Of Vaccinated Efficacy Of Avian Influenza Vaccine In A Scaled Field

Avian influenza (AI) was caused by type A influenza viruses in Orthomyxoviridae family, and has prevailed in many countries in the world. AI can be divided into highly pathogenic AI (HPAI) and low pathogenic AI (LPAI) based on the pathogenicity of AIVs. Because of the destructive consequences caused by HPAI, it was listed as notifiable disease by OIE. Chinese government has posed great concern on the control on HPAI since 2004, and vaccination has been the important component in the strategy used for the control of HPAI because of the national situation. Surveillance and analysis of HI antibody titers of vaccinated chickens are needed to provide theoretical basement for the prevention and control of HPAI.In the current study, we conducted a continuous surveillance of HI antibody titers of avian influenza vaccines-vaccinated chickens in a large chicken field in Shanxi province.we tested the matrnal antibodies of chicks, samples were colleted every 4 days.The results showed that its maternal antibodies decreaed when the chicks grew up.We should be vaccinating for the first in 12～16 days.The antisera samples were got from two ripe breeding birds flocks and two layer chicken flocks at the 7 weeks old on the first time and went on with a interval of 4 weeks. The HI antibody titers were calculated by HI tests.Our data showed that both the H5 and H9 vaccines can induce good HI antibody responses. All HI titers were low at 7 weeks, which were lower than the protective critical value. HI titers increased after first vaccination and reached protective value 3 weeks post vaccination, but with great varying. HI titers can reach high levels after the second and third vaccination, the HI titers against H5 AIVs can reach 9.1 log2 while the HI titers against H9 AIVs can reach 10.79 log2. As for the lay chicken flocks, the HI titers induced by H5 vaccine were well-distributed except the 5th flock. The H9 vaccine induced HI titers in breeding flocks were better than that in layer chicken flocks based on the dispersity.The H9 HI titers, which were higher than the protective critical value, can persist for 11 weeks with 8 log2 in the four flocks. The H5 HI titers, can persist for 8 weeks with 6 log2 in the four flocksSome vaccinated chickens had low HI titers, that may caused by artificial operation in the vaccination, the health situation of the flocks and the breeding situation. Improvement of these factors and complement vaccination may be needed. The vaccination times can be reduced to minimize the vaccine stress to the layer flocks.