Sialoadhesin (Sn) and CD163 have been recognized as two important mediators for porcine reproductive and respiratory syndrome virus (PRRSV) in host macrophages. Recently, it has been demonstrated that the highly virulent Lena strain has a wider macrophage tropism than the low virulent LV strain in the nasal mucosa. Not only CD163+Sn+ macrophages are infected by Lena but also CD163+Sn- macrophages. This suggests that an alternative receptor exists for binding and internalization of PRRSV Lena in the CD163+Sn- macrophages. Further investigation to find the new entry receptor was hampered by the difficulty of isolating these macrophages from the nasal mucosa. In the present study, a new population of CD163+Sn- cells has been identified that is specifically localized in the nasal lamina propria and can be isolated by an intranasal digestion approach. Isolated nasal cells were characterized using specific cell markers and their susceptibility to two different PRRSV-1 strains (LV and Lena) was tested. Upon digestion, 3.2% (flow cytometry)-6.4% (confocal microscopy) of the nasal cells were identified as CD163+ and all (99.7%) of these CD163+ cells were Sn-. These CD163+Sn- cells, designated as "nasal surface macrophages", showed a 4.9 times higher susceptibility to the Lena strain than to the LV strain. Furthermore, the Lena-inoculated cell cultures showed an upregulation of CD163. These results showed that our new cell isolation system is ideal for the further functional and phenotypical analysis of the new population of nasal surface macrophages and further research on the molecular pathogenesis of PRRSV in the nose.

中文翻译：

---

鼻表面巨噬细胞新种群的分离和鉴定及其对PRRSV-1 1型（LV）和3型（Lena）的易感性。

Sialoadhesin（Sn）和CD163被认为是宿主巨噬细胞中猪繁殖与呼吸综合征病毒（PRRSV）的两种重要介体。最近，已经证明，在鼻粘膜中，高毒力的Lena菌株比低毒力的LV菌株具有更宽的巨噬细胞嗜性。Lena不仅感染CD163 + Sn +巨噬细胞，而且也感染CD163 + Sn-巨噬细胞。这表明在CD163 + Sn-巨噬细胞中存在PRRSV莉娜结合和内在化的替代受体。从鼻粘膜分离这些巨噬细胞的困难阻碍了寻找新进入受体的进一步研究。在本研究中，已鉴定出新的CD163 + Sn-细胞群，其特异性定位于鼻固有层，可通过鼻内消化方法分离。使用特异性细胞标记物鉴定分离的鼻细胞，并测试其对两种不同PRRSV-1株（LV和Lena）的敏感性。消化后，鉴定出3.2％（流式细胞仪）-6.4％（鼻镜检查）的鼻细胞为CD163 +，而所有这些CD163 +细胞（99.7％）均为Sn-。这些被称为“鼻表面巨噬细胞”的CD163 + Sn-细胞对Lena菌株的敏感性比对LV菌株的敏感性高4.9倍。而且，接种了莉娜的细胞培养物显示出CD163的上调。这些结果表明，我们的新细胞分离系统非常适合于进一步对新的鼻腔表面巨噬细胞群体进行功能和表型分析，以及进一步研究PRRSV在鼻中的分子发病机理。