猪繁殖与呼吸综合征（PRRS）是由猪繁殖与呼吸综合征病毒（PRRSV）引起的重大传染疫病，每年给全球养猪业带来巨大经济损失。研究发现，PRRSV具有严格的宿主和细胞感染性，CD163是PRRSV感染宿主细胞的必需受体，其第五个富含半胱氨酸的结构域（SRCR5）在感染过程中发挥关键作用。近年来，虽然国内外培育了缺失CD163 SRCR5的抗PRRSV基因编辑猪，但因CD163在体内发挥着重要的生理学功能，唯有进一步解析其参与病毒感染的重要氨基酸位点才能加速该成果产业应用。本项目拟对不同种属CD163 SRCR5结构域进行结构生物学研究，阐明CD163 SRCR5介导PRRSV细胞感染的分子机制，鉴定介导PRRSV入侵的关键氨基酸位点，为防控PRRS提供理论基础。

Porcine reproductive and respiratory syndrome (PRRS), caused by PRRS virus (PRRSV), is a highly contagious disease, which has led to huge economic losses to global pig industry. Previous studies have shown that PRRSV has limited host and cell tropism. CD163 is an indispensable receptor for PRRSV infection and its fifth scavenger receptor cysteine-rich domain (SRCR5) plays a key role. In recent years, although the anti-PRRSV gene-editing pigs lacking CD163 SRCR5 have been bred in the worldwide, CD163 plays an important physiological function in vivo. So analysis of its important residues involved in virus infection could accelerate the industrial application of achievements. This project will determine the structures of CD163 SRCR5 from different species. We will elucidate the mechanisms of CD163 SRCR5 involved in PRRSV cell susceptibility. Moreover, we will identify the key amino acid sites of mediate PRRSV invasion. The knowledge gained from this project will provide a novel basis for prevention and control of PRRS.