Zou Nianli, Xia Jing, Wang Fuyan, Duan Zhenzhen, Miao Dan, Yan Qigui, Cao Sanjie, Wen Xintian, Liu Ping, Huang Yong
College of Veterinary Medicine, Sichuan Agricultural University, Ya'an, Sichuan, 625014, P. R. China; Zigong Center For Disease Control and Prevention, Zi'gong, Sichuan, 643000, P. R. China.
College of Veterinary Medicine, Sichuan Agricultural University, Ya'an, Sichuan, 625014, P. R. China.
Vet Immunol Immunopathol. 2015 Nov 15;168(1-2):49-55. doi: 10.1016/j.vetimm.2015.08.008. Epub 2015 Aug 19.
The spike (S) protein of the infectious bronchitis virus (IBV) plays a central role in the pathogenicity, the immune antibody production, serotype and the tissue tropism. In this study, we generate 11 monoclonal antibodies (mAbs) against S1 subunit of IBV Sczy3 strain, and two mAbs 1D5 and 6A12 were positive in indirect ELISA against both His-S1 protein and the purified whole viral antigen. MAb 6A12 and 1D5 could recognized by other 10 IBV strains (IBVs) from five different genotypes, except that 1D5 had a relatively low reaction with two of the 10 tested IBVs. End-point neutralizing assay performed in chicken embro kidney (CEK) cells revealed that the neutralization titer of 6A12 and 1D5 against Sczy3 reached 1:44.7 and 1:40.6, respectively. After screening a phage display peptide library and peptide scanning, we identified two linear B-cell epitopes that were recognized by the mAbs 1D5 and 6A12, which corresponded to the amino acid sequences (87)PPQGMAW(93) and (412)IQTRTEP(418), respectively, in the IBV S1 subunit. Sequences comparison revealed that epitope (412)IQTRTEP(418) was conserved among IBVs, while the epitope (87)PPQGMAW(93) was relatively variable among IBVs. The novel mAbs and the epitopes identified will be useful for developing diagnostic assays for IBV infections.
传染性支气管炎病毒（IBV）的刺突（S）蛋白在致病性、免疫抗体产生、血清型和组织嗜性中起核心作用。在本研究中，我们制备了11种针对IBV Sczy3株S1亚基的单克隆抗体（mAb），其中两种mAb 1D5和6A12在针对His-S1蛋白和纯化的全病毒抗原的间接ELISA中呈阳性。mAb 6A12和1D5可被来自五种不同基因型的其他10株IBV毒株识别，不过1D5与10株受试IBV中的两株反应相对较弱。在鸡胚肾（CEK）细胞中进行的终点中和试验表明，6A12和1D5对Sczy3的中和效价分别达到1:44.7和1:40.6。通过筛选噬菌体展示肽库和肽扫描，我们鉴定出两个可被mAb 1D5和6A12识别的线性B细胞表位，它们分别对应于IBV S1亚基中的氨基酸序列（87）PPQGMAW（93）和（412）IQTRTEP（418）。序列比较显示，表位（412）IQTRTEP（418）在IBV毒株中保守，而表位（87）PPQGMAW（93）在IBV毒株中相对可变。鉴定出的新型mAb和表位将有助于开发针对IBV感染的诊断检测方法。
