BACKGROUND Porcine epidemic diarrhea virus (PEDV) has caused enormous economic losses to the global pig industry. Currently available PEDV vaccine strains have limited protective effects against PEDV variant strains. METHODS In this study, the highly virulent epidemic virus strain CT was serially passaged in Vero cells for up to 120 generations (P120). Characterization of the different passages revealed that compared with P10 and P64, P120 had a higher viral titer and more obvious cytopathic effects, thereby demonstrating better cell adaptability. RESULTS Pathogenicity experiments using P120 in piglets revealed significant reductions in clinical symptoms, histopathological lesions, and intestinal PEDV antigen distribution; the piglet survival rate in the P120 group was 100%. Furthermore, whole-genome sequencing identified 13 amino acid changes in P120, which might be responsible for the attenuated virulence of P120. CONCLUSIONS Thus, an attenuated strain was obtained via cell passaging and that this strain could be used in preparing attenuated vaccines.

中文翻译：

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Vero细胞减毒猪流行性腹泻病毒CT株的特征和致病性。

背景技术猪流行性腹泻病毒（PEDV）已经给全球养猪业造成了巨大的经济损失。当前可用的PEDV疫苗株对PEDV变异株具有有限的保护作用。方法在本研究中，高毒力流行病毒CT株在Vero细胞中连续传代达120代（P120）。对不同传代的表征表明，与P10和P64相比，P120具有更高的病毒滴度和更明显的细胞病变作用，从而显示出更好的细胞适应性。结果在仔猪中使用P120进行的致病性实验显示，其临床症状，组织病理学病变和肠道PEDV抗原分布显着降低。P120组的仔猪成活率为100％。此外，全基因组测序鉴定出P120中有13个氨基酸变化，这可能是P120毒力减弱的原因。结论因此，通过细胞传代获得了减毒株，该株可用于制备减毒疫苗。