Laboratory of Virology, Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
Vaccine. 2011 Jun 24;29(29-30):4794-804. doi: 10.1016/j.vaccine.2011.04.071. Epub 2011 May 7.
The porcine reproductive and respiratory syndrome virus (PRRSV) is an RNA virus that causes reproductive failure in sows and boars, and respiratory disease in pigs of all ages. Antibodies against several viral envelope proteins are produced upon infection, and the glycoproteins GP4 and GP5 are known targets for virus neutralization. Still, substantial evidence points to the presence of more, yet unidentified neutralizing antibody targets in the PRRSV envelope proteins. The current study aimed to identify and characterize linear antigenic regions (ARs) within the entire set of envelope proteins of the European prototype PRRSV strain Lelystad virus (LV). Seventeen LV-specific antisera were tested in pepscan analysis on GP2, E, GP3, GP4, GP5 and M, resulting in the identification of twenty-one ARs that are capable of inducing antibodies upon infection in pigs. A considerable number of these ARs correspond to previously described epitopes in different European- and North-American-type PRRSV strains. Remarkably, the largest number of ARs was found in GP3, and two ARs in the GP3 ectodomain consistently induced antibodies in a majority of infected pigs. In contrast, all remaining ARs, except for a highly immunogenic epitope in GP4, were only recognized by one or a few infected animals. Sensitivity to antibody-mediated neutralization was tested for a selected number of ARs by in vitro virus-neutralization tests on alveolar macrophages with peptide-purified antibodies. In addition to the known neutralizing epitope in GP4, two ARs in GP2 and one in GP3 turned out to be targets for virus-neutralizing antibodies. No virus-neutralizing antibody targets were found in E, GP5 or M. Since the neutralizing AR in GP3 induced antibodies in a majority of infected pigs, the immunogenicity of this AR was studied more extensively, and it was demonstrated that the corresponding region in GP3 of virus strains other than LV also induces virus-neutralizing antibodies. This study provides new insights into PRRSV antigenicity, and contributes to the knowledge on protective immunity and immune evasion strategies of the virus.
猪繁殖与呼吸综合征病毒（PRRSV）是一种 RNA 病毒，可导致母猪和公猪繁殖失败，以及各年龄段猪只的呼吸道疾病。感染后会产生针对几种病毒包膜蛋白的抗体，糖蛋白 GP4 和 GP5 是已知的病毒中和作用靶标。尽管如此，大量证据表明 PRRSV 包膜蛋白中存在更多但尚未确定的中和抗体靶标。本研究旨在鉴定和表征欧洲原型 PRRSV 株 Lelystad 病毒（LV）整个包膜蛋白中的线性抗原区（AR）。在 pepscan 分析中，用 17 种 LV 特异性抗血清检测 GP2、E、GP3、GP4、GP5 和 M，鉴定出 21 个 AR，这些 AR 能够在猪感染时诱导抗体产生。这些 AR 中有相当数量与不同欧洲和北美型 PRRSV 株中已描述的表位相对应。值得注意的是，GP3 中发现的 AR 数量最多，GP3 外域中的两个 AR 一致地在大多数感染猪中诱导抗体产生。相比之下，除了 GP4 中高度免疫原性的表位外，其余所有的 AR 仅被一个或几个感染动物识别。通过肺泡巨噬细胞体外病毒中和试验，用肽纯化抗体对选定数量的 AR 进行了抗体介导的中和敏感性测试。除了 GP4 中的已知中和表位外，GP2 中的两个 AR 和 GP3 中的一个 AR 也成为病毒中和抗体的靶标。在 E、GP5 或 M 中未发现病毒中和抗体靶标。由于 GP3 中的中和 AR 在大多数感染猪中诱导了抗体，因此更广泛地研究了该 AR 的免疫原性，结果表明 LV 以外的病毒株的 GP3 中相应区域也能诱导病毒中和抗体。本研究为 PRRSV 抗原性提供了新的见解，并为病毒的保护性免疫和免疫逃逸策略提供了知识。
