中山大学陈瑶生教授团队在PRRSV研究领域取得突破性进展 - 中国病毒学论坛|我们一直在坚持！

2017年5月10日，国际病毒学顶级期刊《Journal of Virology》在线发表了中山大学生命科学学院陈瑶生教授团队郭春和博士在PRRSV领域突破性成果“Heparanase upregulation contributes to porcine reproductive and respiratory syndrome virus release”。

该团队郭春和博士一直致力于PRRSV研究。其在PRRSV感染不同时间点发现：病毒感染早期硫酸乙酰肝素（Heparan sulfate, HS）受体表达量升高，以促进病毒吸附；但是，在感染晚期，HS表达量下降，即病毒抑制HS表达。对此，郭博士展开详细研究，他发现PRRSV在感染晚期，病毒需要从细胞膜表面释放出来，而此时膜上的HS会与病毒相互黏连，抑制病毒释放，即HS受体是一把双刃剑。PRRSV为了释放出来，通过激活NF-κB信号通路上调表达乙酰肝素酶Heparanase，并通过激活组织蛋白酶Cathepsin L激活Heparanase，激活的Heparanase迁移到细胞膜上切割HS，抑制其与病毒粒子黏连，从而促进病毒释放（如下图所示）。

本研究首次阐述了PRRSV释放机制，对该病毒防控具有重要指导意义。乙酰肝素酶Heparanase可作为抗PRRSV的重要靶位点。对此，郭春和博士挖掘到锌离子载体Pyrithione通过靶向Heparanase抑制病毒复制，相关研究成果已申报国家发明专利，并发表在中科院一区Veterinary Microbiology杂志上。

Porcine reproductive and respiratory syndrome virus (PRRSV) continues to cause substantial economic losses to the pig industry worldwide. Heparan sulfate (HS) is used by PRRSV for initial attachment to target cells. However, the role of HS in the late phase of PRRSV infection and the mechanism of virus release from host cells remain largely unknown. In this study, we showed that PRRSV infection caused a decrease of HS expression and upregulated heparanase, the only known enzyme capable to degrade HS. We subsequently demonstrated that the NF-κB signaling pathway and cathepsin L protease were involved in regulation of PRRSV infection-induced heparanase. In addition, we found that ablation of heparanase expression using small interfering RNA duplexes increased cell surface expression of HS and suppressed PRRSV replication and release, whereas overexpression of heparanase reduced HS surface expression and enhanced PRRSV replication and release. These data suggest that PRRSV activates NF-κB and cathepsin L to upregulate and process heparanase, then the active heparanase cleave HS, resulting in viral release. Our findings provide new insight into the molecular mechanism of PRRSV egress from host cells, which might help us to further understand PRRSV pathogenesis.