Expression of the C-type lectins DC-SIGN or L-SIGN alters host cell susceptibility for the avian coronavirus, infectious bronchitis virus.

Infectious bronchitis virus (IBV), an avian coronavirus, is a cause of great economic loss in the poultry industry. The virus mainly infects respiratory epithelium, but can be also detected in other organs. The functional receptor for the virus has not been found and field strains of IBV do not infect conventional cell lines. Recently, it has been shown that the C-type lectins DC-SIGN/L-SIGN can promote entry of several coronaviruses. Here we examine whether DC-SIGN/L-SIGN are entry determinants for IBV. We show that by introducing human DC-SIGN/L-SIGN into non-permissive cells, infection by the IBV is dramatically increased. DC-SIGN mediated infection was inhibited by mannan and anti-lectin antibodies, and was independent of sialic acid levels on the cell. Enhancement of IBV infection also occurred for different serotypes of IBV. Our findings demonstrated that even in the absence of avian-specific receptor, DC-SIGN-like lectins are capable of mediating efficient IBV infection.