MBL2 and COVID-19: In this study, the N proteins of highly pathogenic coronaviruses, including SARS-CoV N, MERS-CoV N, and SARS-CoV-2 N, were demonstrated to bind MASP-2 and potentiate the MBL-dependent activation of MASP-2, leading to hyperactivation of the LP complement cascade in vitro, in mice, and in COVID-19 patients (a schematic summary is shown in Fig. 7).