City to activate complement [101]. The frequency of deficient or non-functional MASP-2 ranges from 2 to 19 in different populations with the highest values in Africans [102]. We speculate that relative MBL excess in the setting of relatively low C4 levels or deficient MASP-2 may lead to MBL-mediated enhanced viral infections in clinical settings. Thus, we propose that MBL, C4 and MASP-2, among o