Hosmillo Myra, Sorgeloos Frédéric, Hiraide Rintaro, Lu Jia, Goodfellow Ian, Cho Kyoung-Oh
Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, South Korea.
Division of Virology, Department of Pathology, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK.
J Gen Virol. 2015 Jan;96(Pt 1):74-84. doi: 10.1099/vir.0.071365-0. Epub 2014 Oct 10.
Porcine sapovirus (PSaV) of the family Caliciviridae, is the only member of the genus Sapovirus with cell culture and reverse genetics systems. When combined with the piglet model, these approaches provide a system to understand the molecular basis of sapovirus pathogenesis. The replication of PSaV in cell culture is, however, restricted, displaying an absolute requirement for bile acids and producing lower levels of infectious virus than other caliciviruses. The effect of bile acids has previously been linked to a reduction in the signal transducer and activator of transcription (STAT1)-mediated signalling pathway. In the current study, we observed that even in the presence of bile acids, PSaV replication in cell culture was restricted by soluble factors produced from infected cells. This effect was at least partially due to secreted IFN because treatment of cells with recombinant porcine IFN-β resulted in significantly reduced viral replication. Moreover, IFN-mediated signalling pathways (IFN, STAT1 and the 2',5'-oligoadenylate synthetase) were activated during PSaV infection. Characterization of PSaV growth in cell lines deficient in their ability to induce or respond to IFN showed a 100-150-fold increase in infectious virus production, indicating that the primary role of bile acids was not the inactivation of the innate immune response. Furthermore, the use of IFN-deficient cell lines enabled more efficient recovery of PSaV from cDNA constructs. Overall, the highly efficient cell culture and reverse genetics system established here for PSaV highlighted the key role of the innate immune response in the restriction of PSaV infection and should greatly facilitate further molecular studies on sapovirus host-cell interactions.
杯状病毒科的猪札幌病毒（PSaV）是札幌病毒属中唯一具有细胞培养和反向遗传学系统的成员。当与仔猪模型相结合时，这些方法提供了一个了解札幌病毒发病机制分子基础的系统。然而，PSaV在细胞培养中的复制受到限制，表现出对胆汁酸的绝对需求，并且产生的感染性病毒水平低于其他杯状病毒。胆汁酸的作用此前已与信号转导和转录激活因子（STAT1）介导的信号通路的减少有关。在本研究中，我们观察到即使在存在胆汁酸的情况下，PSaV在细胞培养中的复制仍受到感染细胞产生的可溶性因子的限制。这种效应至少部分归因于分泌的干扰素，因为用重组猪干扰素-β处理细胞会导致病毒复制显著减少。此外，在PSaV感染期间，干扰素介导的信号通路（干扰素、STAT1和2',5'-寡腺苷酸合成酶）被激活。对缺乏诱导或响应干扰素能力的细胞系中PSaV生长的表征显示，感染性病毒产量增加了100-150倍，这表明胆汁酸的主要作用不是使先天免疫反应失活。此外，使用缺乏干扰素的细胞系能够更有效地从cDNA构建体中回收PSaV。总体而言，这里建立的用于PSaV的高效细胞培养和反向遗传学系统突出了先天免疫反应在限制PSaV感染中的关键作用，并应极大地促进对札幌病毒宿主-细胞相互作用的进一步分子研究。
