PRRSV通过调控miR-376-3p表达逃逸TRIM22抗病毒作用的机制研究

Porcine reproductive and respiratory syndrome (PRRS) is a major infectious disease that has adversely impacted the worldwide swine industry. The immune evasion and persistent infection are important scientific issues in control and prevention of PRRSV. Current researches have shown that PRRSV escaped the host innate immune responses by blocking defense system of the host ISGs. Our preliminary experiments showed that PRRSV escaped the antiviral effect of TRIM22 by upregulating the expression of miR-376b-3p. However, the underlying mechanism is not clear. In this project, we will focus on identifying the key transcription factors that regulate miR-376b-3p expression by the methods of promoter truncations, point mutations, EMSA and CHIP to explore the mechanism that PRRSV upregulates miR-376b-3p expression. And then, we will screen and identify the relevant viral protein that interact with TRIM22 by co-immunoprecipitation and cellular localization to clarify that TRIM22 inhibits PRRSV replication by ubiquitinating the viral protein. Our findings will help elucidate the mechanism that PRRSV escape antiviral immune responses, and provide theoretical basis to guide future PRRSV control and prevention.

猪繁殖与呼吸综合征（PRRS）是由猪繁殖与呼吸综合征病毒（PRRSV）引起的一种严重危害世界养猪业最重要传染病，免疫逃逸和持续感染是PRRSV防控的重要科学问题。近年来国内外的研究表明，PRRSV可能通过阻断宿主ISGs防御系统逃逸宿主天然免疫反应。我们前期研究发现，PRRSV能够上调宿主miR-376b-3p的表达逃逸ISGs中TRIM22抗病毒作用，但其相关机制尚不清楚。本项目拟通过启动子截短、点突变、EMSA和CHIP技术，发现调控miR-376b-3p表达的关键转录因子，揭示PRRSV调控miR-376b-3p表达机理；并拟通过免疫共沉淀和细胞共定位等方法，确定与TRIM22互作的PRRSV病毒蛋白，明确TRIM22通过泛素化降解该病毒蛋白而抑制PRRSV复制的机理。该研究结果将有助于阐明PRRSV逃逸机体抗病毒反应机制，为PRRSV防控提供理论基础。

猪繁殖与呼吸综合征（PRRS）是由猪繁殖与呼吸综合征病毒（PRRSV）引起的一种严重危害世界养猪业最重要传染病，其免疫学特征之一是免疫逃逸和持续感染。本课题围绕PRRSV-宿主相互作用过程中PRRSV利用宿主miRNA逃逸抗病毒天然免疫反应这一科学问题。研究发现PRRSV通过病毒非结构蛋白nsp4和nsp11上调宿主miR-376b-3p的表达，miR-376b-3p可以直接靶向病毒限制性因子TRIM22削弱其抗PRRSV活性，从而促进PRRSV的复制。进一步研究发现TRIM22通过与自噬关键蛋白LC3相互作用，激活溶酶体途径，诱导PRRSV核衣壳蛋白N的降解，从而抑制PRRSV的复制。综上所述，PRRSV通过调控miR-376b-3p表达逃逸TRIM22的抗病毒作用。该研究结果将有助于阐明PRRSV逃逸机体抗病毒反应机制，有助于更好地理解PRRSV的发病机制，为PRRSV防控提供理论基础。