Characterization of cellular furin content as a potential factor determining the susceptibility of cultured human and animal cells to coronavirus infectious bronchitis virus infection

In previous studies, the Beaudette strain of coronavirus infectious bronchitis virus (IBV) was adapted from chicken embryo to Vero, a monkey kidney cell line, by serial propagation for 65 passages. To characterize the susceptibility of other human and animal cells to IBV, 15 human and animal cell lines were infected with the Vero-adapted IBV and productive infection was observed in four human cell lines: H1299, HepG2, Hep3B and Huh7. In other cell lines, the virus cannot be propagated beyond passage 5. Interestingly, cellular furin abundance in five human cell lines was shown to be strongly correlated with productive IBV infection. Cleavage of IBV spike protein by furin may contribute to the productive IBV infection in these cells. The findings that IBV could productively infect multiple human and animal cells of diverse tissue and organ origins would provide a useful system for studying the pathogenesis of coronavirus.