| H9N2 subtype avian influenza(H9N2 subtype AI) and infectious bursal disease(IBD) are two important disease which cause serious damage in poultry industry of China. To better prevent and control the two diseases, the epidemiological investigation of H9N2 AI and IBD was did, the phylogenetic analysis of hemagglutinin(HA) genes from 11 isolates of H9N2 subtype AIV was performed, and the combined highly immunized egg yolk antibody of H9N2 subtype AI and IBD was developed and primarily applied.The epidemiological investigation of H9N2 subtype AI and IBD in Henan province was performed by statistical analysis of clinic cases from Poultry Institute, Henan Agricultural University in 2014. The results showed that, in total of 453 cases, the positive rate of H9N2 subtype AI was 20.75%(95% CI 17.1, 24.8), of which the positive rate of layer was 20.37%(95% CI 16.4, 24.8), and the positive rate of broiler was 22.67%(95% CI 13.8, 33.8); the positive rate of IBD was 1.55%(95% CI 0.6, 3.2), of which the positive rate of layer was 1.06%(95% CI 0.3, 2.7), and the positive rate of broiler was 4.00%(95% CI 0.8, 11.2). In addition, the cases of H9N2 subtype AI were mainly occuring in 1-6 months, while IBD were in 1-3 months. What is more, the positive rates of the two diseases were commonly higher in relatively high-density breeding region. Briefly, H9N2 subtype AI and IBD were prevalent in Henan province in 2014, but the morbidity rate of IBD was much lower. This provides epidemiological data and experiment basis for prevention and control of the two diseases.The HA genes from 11 strains of H9N2 subtype AIV isolated from part regions of Henan during 2010-2013 were used for phylogenetic analysis. The nucleotide homology and amino acid homlogy of 11 HA genes were 9.5-99.9% and 91.6-99.8%, respectively, indicating that all HA genes belonged to Eurasian lineage. According to the phylogenetic analysis, the isolates of CK/HN/XC/10, CK/HN/XC2/10, CK/HN/SQ/11, CK/HN/XY1/11, CK/HN/ZK1/11, CK/HN/XY2/11 and CK/HN/LY/13 were evolved from Bird/GX/62/05, which belonged to the same branch with G97 and Y280 strains isolated from Honhkong. The isolates of CK/HN/JZ/11, CK/HN/KF/11, CK/HN/ZK2/12 and CK/HN/LH/121 were evolved from CK/HN/JZ/11 and CK/HN/LH/121, which belonged to the same branch with environment/Hunan/1-70/07, feces/Hunan/2-28/07 and feces/Hunan/3-91/07 strains. The results suggested that there was variation in H9N2 subtype AIV, which had potential menace of the viral transmission and evolution in different animal reservoir. And the molecular epidemiological investigation and research of H9N2 subtype AIV were sure to be enhanced.The oil-emulsion inactivated vaccine of H9N2 subtype AIV and IBDV were prepared based on the improved technology, respectively. 160 day-old layers were immunized for the development of the combined highly immunized egg yolk antibody, and then the egg yolk was collected by Octylic acid method. Through sterility testing, exogenous virus detection, animal safety testing and chichen embryo inoculation test, the egg yolk antibody was up to standard.The results of prevention and treatment test of artificial infection and the primary application in clinic cases showed that, for H9N2 subtype AIV, the protection rate of prevention was 86.7%, the treatment rate of protection was 80.0%; for IBDV, the treatment rate of protection was 86.7%, the treatment rate of clinic cases was 82.3%. Briefly, the combined highly immunized egg yolk antibody was efficient for H9N2 subtype AI and IBD, and this study provides epidemiological data and experiment basis for the clinical application of highly immunized egg yolk antibody. |
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