Mannose-binding lectin is a pattern-recognition molecule, which provides first line of host defense. Accumulating evidence has suggested that MBL exhibits in vitro anti-influenza virus properties by direct neutralization, inhibiting influenza virus hemagglutination, binding to the influenza virus as an opsonin, and activating the complement system through the lectin pathway [14, 16, 23] . However, these properties vary among different virus strains and subtypes [17, 18] . In this study, we focused on the pandemic influenza A H1N1 virus and avian influenza A H9N2/G1 virus, which are of potential threat to the global community.