Infection of the tracheal epithelium by infectious bronchitis virus is sialic acid dependent

Avian Infectious bronchitis virus (IBV) is a coronavirus that infects chickens via the respiratory epithelium as primary target cells. The binding of coronaviruses to the cell surface is mediated by the viral surface protein S. Recently we demonstrated that alpha2,3-linked sialic acid serves as a receptor determinant for IBV on Vero cells and primary chicken embryo kidney cells. Here we analyze the importance of the sialic acid binding activity for the infection of tracheal organ cultures (TOCs) by different IBV strains. Our results show that alpha2,3-linked sialic acid also serves as a receptor determinant on chicken TOCs. Infection of TOCs by IBV results in ciliostasis. Desialylation induced by neuraminidase treatment of tracheal organ cultures prior to infection by IBV delayed the ciliostatic effect or resulted in partial loss of ciliary activity. This effect was observed with both respiratory and nephropathogenic strains. Inhibition of ciliostasis was also observed when TOCs were pretreated with an alpha2,3-specific neuraminidase. Analysis of the tracheal epithelium for reactivity with lectins revealed that the susceptible cells in the epithelium abundantly express alpha2,3-linked sialic acid. These results indicate that alpha2,3-linked sialic acid plays an important role for infection of the respiratory epithelium by IBV.