MARCO调节猪繁殖与呼吸综合征病毒感染的分子机制

CD163是PRRSV感染必需受体。MARCO与CD163一样，在PAMs细胞表面特异表达，属于清道夫受体，提示MARCO在PRRSV感染中可能具有重要的作用。我们通过单细胞测序发现PRRSV感染PAMs后，MARCO表达量显著下降，且大部分细胞不表达MARCO，这个现象细胞试验结果进一步得到验证，提示MARCO与PRRSV感染有关。在此基础上，本项目拟利用单细胞测序技术的精确性将PAMs分为三个不同的亚群，然后分析三个亚群中PRRSV感染率高低与MARCO表达量相关性；阐明MARCO与PRRSV特定蛋白互作，进而介导病毒进入，揭示其调节PRRSV感染的分子机制；并通过CRISPR/Cas9基因编辑技术培育MARCO分子敲除猪，在活体水平进一步验证其对PRRSV感染作用。预期研究结果不仅可确证MARCO可调节PRRSV感染，还可为挖掘PRRSV抗病/易感基因奠定基础。

CD163 receptor is necessary for porcine reproductive and respiratory syndrome virus (PRRSV) infection. Macrophage receptor with collagenous structure (MARCO) receptor, which is the same as CD163, belongs to scavenger receptor and specially expresses on porcine alveolar macrophages (PAMs), indicating that MARCO may play an important role in PRRSV infection. We found that the expression of MARCO was reduced in PAMs after PRRSV infection via a single-cell sequence. And this phenomenon was also demonstrated by western blot and qPCR assays in vitro. These data suggests PRRSV infection can regulate MARCO expression. Based on these results, we plan to analyze the relationship between PRRSV infection rate and MARCO expression in the three subpopulations of PAMs using a single-cell sequence; and then we illuminate which domain of MARCO interacts with PRRSV to mediate the virus entry, revealing the molecular mechanisms of MARCO regulating PRRSV infection; finally we cultivate MARCO-knock out pigs using CRISPR/Cas9 and investigate the resistance to PRRSV infection in vivo. The data not only confirm the role of MARCO in PRRSV replication, but also provide new theoretical basis for screening susceptibility or resistance genes against the virus.