Highly pathogenic coronavirus N protein aggravates lung injury by MASP-2-mediated complement over-activation

Ting Gao; Mingdong Hu; Xiaopeng Zhang; Hongzhen Li; Lin Zhu; Hainan Liu; Qincai Dong; Zhang Zhang; Zhongyi Wang; Yong Hu; Yangbo Fu; Yanwen Jin; Kaitong Li; Songtao Zhao; Yongjiu Xiao; Shuping Luo; Lufeng Li; Lingfang Zhao; Junli Liu; Huailong Zhao; Yue Liu; Weihong Yang; Jing Peng; Xiaoyu Chen; Ping Li; Yaoning Liu; Yonghong Xie; Jibo Song; Lu Zhang; Qingjun Ma; Xiuwu Bian; Wei Chen; Xuan Liu; Qing Mao; Cheng Cao

To investigate the complement activation in lung of mice induced by LPS and N protein, mice pre-infected with Ad-SARS N (1×10 8 PFU) were challenged with LPS (5 mg/kg). At 6 hr post LPS administration, the mice were sacrificed, and the paraformaldehyde-fixed lung tissue 35 was subjected to immunohistochemical (IHC) staining with anti-C4b antibody or immunofluorescence analysis with FITC-labeled anti-C3c antibody. The C4b and activated C3 deposition in the lung were significantly increased in mice expressing SARS-CoV N protein ( Fig. S3A ). 40 The in vivo association of MASP-2 with the N protein was further assessed by in situ proximity ligation assay (PLA) with anti-N and anti-MASP-2 antibodies (the left panels of Fig. 3D and S3A), and red signals, which were only detectable when SARS-CoV N and MASP-2 bind to each other, were abundantly observed in pulmonary cells from mice expressing SARS-All rights reserved. No reuse allowed without permission. the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.