Fan Baochao, Liu Xing, Bai Juan, Zhang Tingjie, Zhang Qiaoya, Jiang Ping
Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.
Virus Res. 2015 Jun 2;204:21-30. doi: 10.1016/j.virusres.2015.04.015. Epub 2015 Apr 20.
Porcine reproductive and respiratory syndrome virus (PRRSV) is mainly responsible for the heavy economic losses in pig industry in the world. A number of neutralizing epitopes have been identified in the viral structural proteins GP3, GP4, GP5 and M. In this study, the important amino acid (aa) residues of HP-PRRSV strain BB affecting neutralization susceptibility of antibody were examined using resistant strains generated under neutralizing antibody (NAb) pressure in MARC-145 cells, reverse genetic technique and virus neutralization assay. HP-PRRSV strain BB was passaged under the pressure of porcine NAb serum in vitro. A resistant strain BB34s with 102 and 104 aa substitutions in GP5, which have been predicted to be the positive sites for pressure selection (Delisle et al., 2012), was cloned and identified. To determine the effect of the two aa residues on neutralization, eight recombinant PRRSV strains were generated, and neutralization assay results confirmed that the aa residues 102 and 104 in GP5 played an important role in NAbs against HP-PRRSV in MARC-145 cells and porcine alveolar macrophages. Alignment of GP5 sequences revealed that the variant aa residues at 102 and 104 were frequent among type 2 PRRSV strains. It may be helpful for understanding the mechanism regulating the neutralization susceptibility of PRRSV to the NAbs and monitoring the antigen variant strains in the field.
猪繁殖与呼吸综合征病毒（PRRSV）是造成全球养猪业巨大经济损失的主要原因。已在病毒结构蛋白GP3、GP4、GP5和M中鉴定出多个中和表位。在本研究中，利用在MARC-145细胞中经中和抗体（NAb）压力产生的抗性毒株、反向遗传技术和病毒中和试验，检测了高致病性PRRSV毒株BB影响抗体中和敏感性的重要氨基酸（aa）残基。高致病性PRRSV毒株BB在猪NAb血清压力下进行体外传代。克隆并鉴定了一株在GP5中有102和104个氨基酸替换的抗性毒株BB34s，这些替换位点已被预测为压力选择的阳性位点（Delisle等人，2012年）。为了确定这两个氨基酸残基对中和作用的影响，构建了8株重组PRRSV毒株，中和试验结果证实，GP5中的102和104位氨基酸残基在MARC-145细胞和猪肺泡巨噬细胞中对高致病性PRRSV的NAb产生中起重要作用。GP5序列比对显示，102和104位的变异氨基酸残基在2型PRRSV毒株中很常见。这可能有助于理解调节PRRSV对NAb中和敏感性的机制，并监测田间的抗原变异毒株。
