College of Veterinary Medicine, University of Minnesota, St. Paul, MN, United States.
The Pirbright Institute, Pirbright, United Kingdom.
Front Immunol. 2021 Feb 22;12:638493. doi: 10.3389/fimmu.2021.638493. eCollection 2021.
Porcine reproductive and respiratory syndrome (PRRS) is a devastating disease which impacts the pig industry worldwide. The disease is caused by PRRS viruses (PRRSV-1 and -2) which leads to abortions and other forms of reproductive failure in sows and severe respiratory disease in growing pigs. Current PRRSV vaccines provide limited protection; only providing complete protection against closely related strains. The development of improved PRRSV vaccines would benefit from an increased understanding of epitopes relevant to protection, including those recognized by antibodies which possess the ability to neutralize distantly related strains. In this work, a reverse vaccinology approach was taken; starting first with pigs known to have a broadly neutralizing antibody response and then investigating the responsible B cells/antibodies through the isolation of PRRSV neutralizing monoclonal antibodies (mAbs). PBMCs were harvested from pigs sequentially exposed to a modified-live PRRSV-2 vaccine as well as divergent PRRSV-2 field isolates. Memory B cells were immortalized and a total of 5 PRRSV-specific B-cell populations were isolated. All identified PRRSV-specific antibodies were found to be broadly binding to all PRRSV-2 isolates tested, but not PRRSV-1 isolates. Antibodies against GP5 protein, commonly thought to possess a dominant PRRSV neutralizing epitope, were found to be highly abundant, as four out of five B cells populations were GP5 specific. One of the GP5-specific mAbs was shown to be neutralizing but this was only observed against homologous and not heterologous PRRSV strains. Further investigation of these antibodies, and others, may lead to the elucidation of conserved neutralizing epitopes that can be exploited for improved vaccine design and lays the groundwork for the study of broadly neutralizing antibodies against other porcine pathogens.
猪繁殖与呼吸综合征（PRRS）是一种具有毁灭性的疾病，影响着全球的养猪业。该疾病由 PRRS 病毒（PRRSV-1 和 -2）引起，可导致母猪流产和其他形式的繁殖失败，以及生长猪严重的呼吸道疾病。目前的 PRRSV 疫苗提供的保护有限；仅能针对密切相关的毒株提供完全保护。开发改良的 PRRSV 疫苗将得益于对相关表位的深入了解，包括那些被具有中和相关毒株能力的抗体识别的表位。在这项工作中，我们采用了反向疫苗学方法；首先从已知具有广泛中和抗体反应的猪开始，然后通过分离 PRRSV 中和单克隆抗体（mAb）来研究负责的 B 细胞/抗体。从连续暴露于改良活 PRRSV-2 疫苗和不同 PRRSV-2 田间分离株的猪中采集 PBMC。记忆 B 细胞被永生化，总共分离出 5 个 PRRSV 特异性 B 细胞群体。所有鉴定出的 PRRSV 特异性抗体都被发现能广泛结合所有测试的 PRRSV-2 分离株，但不能结合 PRRSV-1 分离株。针对 GP5 蛋白的抗体通常被认为具有主导的 PRRSV 中和表位，被发现高度丰富，因为 5 个 B 细胞群体中有 4 个是 GP5 特异性的。其中一种 GP5 特异性 mAb 被证明具有中和作用，但仅在针对同源而非异源 PRRSV 株时观察到。对这些抗体和其他抗体的进一步研究可能会揭示保守的中和表位，从而可以用于改进疫苗设计，并为研究针对其他猪病原体的广泛中和抗体奠定基础。
