Yan Fang, Zhao Yujun, Yue Wenbin, Yao J, Lihua Lv, Ji Wenhui, Li Xuying, Liu Fengbo, Wu Qian
College of Animal Science and Technology, Shanxi Agricultural University, Taigu, China 030801.
Avian Dis. 2011 Sep;55(3):451-8. doi: 10.1637/9446-070510-ResNote.1.
Between 2006 and 2009, seven strains of infectious bronchitis (IB) virus (IBV) were isolated from vaccinated chicken flocks on different chicken farms in China. The pathogenic characters of seven IBV strains were assessed. Each of the seven strains was infective to the test chickens and could induce an immune response. The results from chicken embryo cross-neutralization assays showed that these strains were antigenically distinct from classic IBV strains of H120, M41, Conn, and Gray. Compared to H120 vaccine strain, point mutation, short insertion, and deletion occurred at many positions in the S1 protein of the seven strains. Five of the seven strains had the motif (HRRRR), which was identical to that of the epidemic IBV strains in China. Two new motifs (HRLRR and RRIRR) emerged in the isolated strains. The homology of the nucleotide and amino acid sequences of the S1 gene among the seven isolates was 81.7%-99.7% and 79.0%-99.4%, respectively. These seven strains were also genetically different from the vaccine strains and non-China IBV strains but closely related to large numbers of Chinese strains. The seven isolates and 36 reference IBV strains were clustered into six distinct groups (I-VI). The seven strains were categorized into groups I, II, and III, forming a big phylogenetic branch, which is closely related to Chinese IBVs, whereas the vaccine strains belonging to group VI are genetically distant from groups I, II, and III. The results from this study indicate that different IBV strains cocirculate in the chicken population in China.
2006年至2009年间，在中国不同养鸡场的免疫鸡群中分离出7株传染性支气管炎（IB）病毒（IBV）。对这7株IBV毒株的致病特性进行了评估。这7株毒株中的每一株都能感染试验鸡并能诱导免疫反应。鸡胚交叉中和试验结果表明，这些毒株在抗原性上与经典的H120、M41、Conn和Gray IBV毒株不同。与H120疫苗株相比，这7株毒株的S1蛋白在许多位置发生了点突变、短插入和缺失。7株毒株中有5株具有基序（HRRRR），这与中国流行的IBV毒株相同。在分离出的毒株中出现了两个新的基序（HRLRR和RRIRR）。7株分离株的S1基因核苷酸和氨基酸序列同源性分别为81.7%-99.7%和79.0%-99.4%。这7株毒株在基因上也与疫苗株和非中国IBV毒株不同，但与大量中国毒株密切相关。这7株分离株和36株参考IBV毒株被聚类为6个不同的组（I-VI）。这7株毒株被归类为I、II和III组，形成一个大的系统发育分支，与中国IBV密切相关，而属于VI组的疫苗株在基因上与I、II和III组相距较远。本研究结果表明，不同的IBV毒株在中国鸡群中共同传播。
