Spatiotemporal Interplay of Severe Acute Respiratory Syndrome Coronavirus and Respiratory Mucosal Cells Drives Viral Dissemination in Rhesus Macaques

Liu, Li; Wei, Qiang; Nishiura, Kenji; Peng, Jie; Wang, Haibo; Midkiff, Cecily; Alvarez, Xavier; Qin, Chuan; Lackner, Andrew; Chen, Zhiwei

Innate immune responses play a critical role in the control of early virus replication and dissemination. It remains unknown, however, how SARS-CoV evades respiratory innate immunity to establish a systemic infection. Here, we show in Chinese macaques that SARS-CoV traversed the mucosa through the respiratory tract within 2 days, resulting in extensive mucosal infiltration by T cells, MAC387(+) and CD163(+) monocytes/macrophages followed by limited viral replication in the lung but persistent viral shedding into the upper airway. Mucosal monocytes/macrophages sequestered virions in intracellular vesicles together with infected Langerhans cells (LCs) and migrated into the tonsils and/or draining lymph nodes (LNs) within 2 days. In lymphoid tissues, viral RNA and proteins were detected in infected monocytes upon differentiation into dendritic cells (DCs) within 3 days. Systemic viral dissemination was observed within 7 days. This study provides a comprehensive overview of the spatiotemporal interactions of SARS-CoV, monocytes/macrophages and the dendritic cell network in mucosal tissues and highlights the fact that while these innate cells contribute to viral clearance, they probably also serve as shelters and vehicles to provide a mechanism for the virus to escape host mucosal innate immunity and disseminate systemically.