Cholangiocyte expression of α₂β₁-integrin confers susceptibility to rotavirus-induced experimental biliary atresia

Inoculation of BALB/c mice with rhesus rotavirus (RRV) in the newborn period results in biliary epithelial cell (cholangiocyte) infection and the murine model of biliary atresia. Rotavirus infection of a cell requires attachment, which is governed in part by cell-surface expression of integrins such as α₂β₁. We hypothesized that cholangiocytes were susceptible to RRV infection because they express α₂β₁. RRV attachment and replication was measured in cell lines derived from cholangiocytes and hepatocytes. Flow cytometry was performed on these cell lines to determine whether α₂β₁ was present. Cholangiocytes were blocked with natural ligands, a monoclonal antibody, or small interfering RNA against the α₂-subunit and were infected with RRV. The extrahepatic biliary tract of newborn mice was screened for the expression of the α₂β₁-integrin. Newborn mice were pretreated with a monoclonal antibody against the α2-subunit and were inoculated with RRV. RRV attached and replicated significantly better in cholangiocytes than in hepatocytes. Cholangiocytes, but not hepatocytes, expressed α₂β₁ in vitro and in vivo. Blocking assays led to a significant reduction in attachment and yield of virus in RRV-infected cholangiocytes. Pretreatment of newborn pups with an anti-α₂ monoclonal antibody reduced the ability of RRV to cause biliary atresia in mice. Cell-surface expression of the α₂β₁-integrin plays a role in the mechanism that confers cholangiocyte susceptibility to RRV infection.