Avian Influenza Viruses Infect Primary Human Bronchial Epithelial Cells Unconstrained by Sialic Acid α2,3 Residues

Avian influenza viruses (AIV) are an important emerging threat to public health. It is thought that sialic acid (sia) receptors are barriers in cross-species transmission where the binding preferences of AIV and human influenza viruses are sias alpha 2,3 versus alpha 2,6, respectively. In this study, we show that a normal fully differentiated, primary human bronchial epithelial cell model is readily infected by low pathogenic H5N1, H5N2 and H5N3 AIV, which primarily bind to sia alpha 2,3 moieties, and replicate in these cells independent of specific sias on the cell surface. NHBE cells treated with neuraminidase prior to infection are infected by AIV despite removal of sia alpha 2,3 moieties. Following AIV infection, higher levels of IP-10 and RANTES are secreted compared to human influenza virus infection, indicating differential chemokine expression patterns, a feature that may contribute to differences in disease pathogenesis between avian and human influenza virus infections in humans.