Human coronavirus NL63 (HCoV-NL63) is a member of the family Coronaviridae, genus Alphacoronavirus, and was first discovered in 2004 (1). HCoV-NL63 is mainly associated with the common cold in children, the elderly, and immunocompromised patients (2, 3). The genome of HCoV-NL63 is about 27 kb with a conserved gene order of 5′-orf1ab-spike (S)-orf3-envelope (E)-membrane (M)-nucleocapsid (N)-poly (A). The species tropism of HCoV-NL63 is determined by spike glycoprotein. HCoV-NL63 and severe acute respiratory syndrome coronavirus (SARS-CoV) share the same cell receptor, angiotensin converting enzyme 2 (ACE-2) (4, 5), for entry into host cells, and HCoV-NL63 is recognized as a common cause of upper respiratory tract infection and has been prevalent worldwide.