Ma Zhiqian, Li Zhiwei, Li Yongqi, Zhao Xiaojing, Zheng Congsen, Li Yang, Guo Xuyang, Xu Lele, Zheng Zifang, Liu Guangliang, Zheng Haixue, Xiao Shuqi
State Key Laboratory for Animal Disease Control and Prevention, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China.
College of Veterinary Medicine, Lanzhou University, Lanzhou, Gansu, China.
J Virol. 2025 Apr 15;99(4):e0209224. doi: 10.1128/jvi.02092-24. Epub 2025 Mar 4.
Since 2010, highly virulent mutant GII subtype porcine epidemic diarrhea virus (PEDV) strains derived from GI subtype strains have caused significant economic losses in the pig industry. However, the molecular mechanism of PEDV virulence evolution remains unclear. It has been predicted that, compared to the S proteins of GI strains, five N-linked glycosylation sites have changed in the highly virulent GII PEDV strains. To investigate how changes in these sites affect PEDV virulence, we constructed five recombinant strains harboring the above mutation sites using the GII subtype rPEDV-S as the backbone, among which rPEDV-S, rPEDV-S, rPEDV-S, and rPEDV-S were successfully rescued, but rPEDV-S was not. Compared to infection with rPEDV-S (100%), infection with rPEDV-S and rPEDV-S resulted in lower mortality in piglets (33%), and although rPEDV-S and rPEDV-S resulted in high mortality (100%), death was delayed. All surviving piglets were challenged orally with rPEDV-S at 21 days post-infection. The piglets in the rPEDV-S and rPEDV-S groups produced high levels of IgG, IgA, and cross-protective neutralizing antibodies, which protected the piglets after rPEDV-S challenge. Furthermore, the change in the structures of the rPEDV-S and rPEDV-S S proteins predicted with high precision by AlphaFold 3 may be the cause of the attenuated virulence. Our data provide a unique perspective on the molecular mechanism of PEDV virulence evolution from the GI to the GII subtype and identify the targets of PED live attenuated vaccines.
The continuous emergence of novel viral variants in the current landscape poses challenges for disease prevention and control. Before 2010, PED caused by GI strains was only sporadic outbreaks and not large-scale epidemics. Since 2010, highly virulent GII strains derived from GI strains have spread worldwide and caused significant economic losses. However, the molecular mechanism underlying the differences in virulence is still unclear. In this study, the differences in the predicted glycosylation sites of the S protein between the GI and GII strains were taken as the starting point to explore the key sites responsible for the variations in PEDV virulence. The results indicate that the motifs 57ENQGVNST64 and 722NSTF725 of the S protein in the GII strains are involved in the evolution of PEDV virulence. This study provides a new perspective on the molecular mechanism of PEDV virulence evolution.
自2010年以来，源自GI亚型毒株的高致病性GII亚型猪流行性腹泻病毒（PEDV）毒株给养猪业造成了重大经济损失。然而，PEDV毒力进化的分子机制仍不清楚。据预测，与GI毒株的S蛋白相比，高致病性GII型PEDV毒株中有五个N - 糖基化位点发生了变化。为了研究这些位点的变化如何影响PEDV毒力，我们以GII亚型rPEDV - S为骨架构建了五个含有上述突变位点的重组毒株，其中rPEDV - S、rPEDV - S、rPEDV - S和rPEDV - S成功拯救出来，但rPEDV - S未成功。与感染rPEDV - S（死亡率100%）相比，感染rPEDV - S和rPEDV - S导致仔猪死亡率较低（33%），虽然rPEDV - S和rPEDV - S导致高死亡率（100%），但死亡延迟。所有存活仔猪在感染后21天用rPEDV - S进行口服攻毒。rPEDV - S和rPEDV - S组的仔猪产生了高水平的IgG、IgA和交叉保护性中和抗体，这些抗体在rPEDV - S攻毒后保护了仔猪。此外，通过AlphaFold 3高精度预测的rPEDV - S和rPEDV - S S蛋白结构变化可能是毒力减弱的原因。我们的数据为PEDV从GI亚型到GII亚型毒力进化的分子机制提供了独特视角，并确定了PED活疫苗减毒的靶点。
在当前形势下，新型病毒变体的不断出现给疾病预防和控制带来了挑战。2010年之前，由GI毒株引起的PED只是零星爆发，并非大规模流行。自2010年以来，源自GI毒株的高致病性GII毒株已在全球传播并造成重大经济损失。然而，毒力差异背后的分子机制仍不清楚。在本研究中，以GI和GII毒株S蛋白预测的糖基化位点差异为出发点，探索负责PEDV毒力变化的关键位点。结果表明，GII毒株S蛋白的基序57ENQGVNST64和722NSTF725参与了PEDV毒力的进化。本研究为PEDV毒力进化的分子机制提供了新的视角。
