Senecavirus A (SVA) is a picornavirus that circulates in swine populations worldwide causing vesicular disease (VD) in affected animals. Here we developed a reverse genetics system for SVA based on the well-characterized wild-type SVA strain SD15-26 (wt SVA SD15-26). The full-length cDNA genome of SVA was cloned into a plasmid under a T7 RNA polymerase promoter. Following in vitro transcription, the genomic viral RNA was transfected into BHK-21 cells and rescue of infectious virus (rSVA SD15-26) was shown by inoculation of highly susceptible H1299 cells. In vitro characterization of the rSVA SD15-26 showed similar replication properties and protein expression levels as the wt SVA SD15-26. A pathogenesis study was conducted in 15-week-old finishing pigs to evaluate the pathogenicity and infection dynamics of the rSVA SD15-26 virus in comparison to the wt SVA SD15-26. Animals from both rSVA- and wt SVA SD15-26-inoculated groups presented characteristic SVA clinical signs (lethargy and lameness) followed by the development of vesicular lesions on the snout and/or feet. The clinical outcome of infection, including disease onset, severity and duration was similar in rSVA- and the wt SVA SD15-26-inoculated animals. All animals inoculated with rSVA or with wt SVA SD15-26 presented a short-term viremia, and animals from both groups shed similar amounts of virus in oral and nasal secretion, and faeces. Our data demonstrates that the rSVA SD5-26 clone is fully virulent and pathogenic in pigs, presenting comparable pathogenesis and infection dynamics to the wt SVA SD15-26 strain. The infectious clone generated here is a useful platform to study virulence determinants of SVA, and to dissect other aspects of SVA infection biology, pathogenesis and persistence.

中文翻译：

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塞内卡病毒 A 的毒性和致病性传染性克隆

塞内卡病毒 A (SVA) 是一种微小核糖核酸病毒，它在世界范围内的猪群中传播，在受影响的动物中引起水疱病 (VD)。在这里，我们基于充分表征的野生型 SVA 菌株 SD15-26 (wt SVA SD15-26) 开发了 SVA 的反向遗传学系统。在 T7 RNA 聚合酶启动子下，将 SVA 的全长 cDNA 基因组克隆到质粒中。以下体外转录，基因组病毒RNA转染到BHK-21细胞和感染性病毒（RSVA SD15-26）的救援用高度敏感H1299细胞的接种所示。体外rSVA SD15-26 的表征显示出与 wt SVA SD15-26 相似的复制特性和蛋白质表达水平。在 15 周龄育肥猪中进行了发病机制研究，以评估 rSVA SD15-26 病毒与 wt SVA SD15-26 相比的致病性和感染动态。来自 rSVA 和野生型 SVA SD15-26 接种组的动物都表现出特征性的 SVA 临床症状（嗜睡和跛行），随后在鼻子和/或脚上出现水泡病变。感染的临床结果，包括疾病发作、严重程度和持续时间，在 rSVA 和 wt SVA SD15-26 接种的动物中是相似的。所有接种 rSVA 或 wt SVA SD15-26 的动物都出现短期病毒血症，两组动物的口腔和鼻腔分泌物以及粪便中排出的病毒量相似。我们的数据表明 rSVA SD5-26 克隆在猪中具有完全的毒性和致病性，呈现出与 wt SVA SD15-26 菌株相当的发病机制和感染动力学。此处生成的传染性克隆是研究 SVA 毒力决定因素和剖析 SVA 感染生物学、发病机制和持久性的其他方面的有用平台。