VanderBurgt Jordan T, Harper Ondre, Garnham Christopher P, Kohalmi Susanne E, Menassa Rima
Biology Department, University of Western Ontario, London, ON, Canada.
London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON, Canada.
Front Plant Sci. 2023 Jan 24;14:1044675. doi: 10.3389/fpls.2023.1044675. eCollection 2023.
Porcine reproductive and respiratory syndrome (PRRS) is a disease leading to spontaneous abortions and stillbirths in sows and lowered life quality and expectancy in growing pigs. PRRS is prevalent worldwide and has significant economic impacts to swine industries around the globe. Co-expression of the two most abundant proteins in the viral envelope, the matrix protein (M) and glycosylated protein 5 (GP5), can produce a neutralizing immune response for the virus providing a potentially effective subunit vaccine against the disease, but these proteins are difficult to express. The goal of this research was to display antigenic portions of the M and GP5 proteins on the surface of tobacco mosaic virus-like particles. A modified tobacco mosaic virus coat protein (TMVc) was transiently expressed in leaves and targeted to three subcellular compartments along the secretory pathway to introduce glycosylation patterns important for M-GP5 epitope immunogenicity. We found that accumulation levels in the apoplast were similar to the ER and the vacuole. Because glycans present on plant apoplastic proteins are closest to those present on PRRSV proteins, a TMVc-M-GP5 fusion construct was targeted to the apoplast and accumulated at over 0.5 mg/g of plant fresh weight. TMVc virus-like particles self-assembled in plant cells and surface-displayed the M-GP5 epitope, as visualized by transmission electron microscopy and immunogold localization. These promising findings lay the foundation for immunogenicity and protective-immunity studies in animals to examine the efficacy of this vaccine candidate as a measure to control PRRS.
猪繁殖与呼吸综合征（PRRS）是一种导致母猪自然流产和死产，以及生长猪生活质量和预期寿命降低的疾病。PRRS在全球范围内流行，对全球养猪业产生重大经济影响。病毒包膜中两种最丰富的蛋白质，即基质蛋白（M）和糖基化蛋白5（GP5）的共表达，可以产生针对该病毒的中和免疫反应，从而提供一种潜在有效的抗该疾病的亚单位疫苗，但这些蛋白质难以表达。本研究的目的是在烟草花叶病毒样颗粒表面展示M和GP5蛋白的抗原部分。一种修饰的烟草花叶病毒外壳蛋白（TMVc）在叶片中瞬时表达，并靶向分泌途径中的三个亚细胞区室，以引入对M-GP5表位免疫原性重要的糖基化模式。我们发现质外体中的积累水平与内质网和液泡中的相似。由于植物质外体蛋白上存在的聚糖与PRRSV蛋白上存在的聚糖最接近，因此将TMVc-M-GP5融合构建体靶向质外体，并以超过0.5mg/g植物鲜重的量积累。通过透射电子显微镜和免疫金定位观察到，TMVc病毒样颗粒在植物细胞中自组装并在表面展示M-GP5表位。这些有前景的发现为在动物中进行免疫原性和保护性免疫研究奠定了基础，以检验这种候选疫苗作为控制PRRS措施的有效性。
