Differential infection of polarized epithelial cell lines by sialic acid-dependent and sialic acid-independent rotavirus strains

Infection of epithelial cells by some animal rotaviruses, but not human or most animal rotaviruses, requires the presence of N-acetylneuraminic (siali c) acid (SA) on the cell surface for efficient infectivity. To further unde rstand how rotaviruses enter susceptible cells, six different polarized epi thelial cell lines, grown on permeable filter membrane supports containing 0.4-mum pores, were infected apically or basolaterally with SA-independent or SA-dependent rotaviruses. SA-independent rotaviruses applied apically or basolaterally were capable of efficiently infecting both sides of the epit helium of all six polarized cell lines tested, while SA-dependent rotavirus es only infected efficiently through the apical surface of five of the pola rized cell lines tested. Regardless of the route of virus entry, SA-depende nt and SA-independent rotaviruses were released almost exclusively from the apical domain of the plasma membrane of polarized cells before monolayer d isruption or cell lysis. The transepithelial electrical resistance (TER) of cells decreased at the same time, irrespective of whether infection with S A-independent rotaviruses occurred apically or basolaterally. The TER of ce lls infected apically with SA-dependent rotaviruses decreased earlier than that of cells infected basolaterally. Rotavirus infection decreased TER bef ore the appearance of cytopathic effect and cell death and resulted in an i ncrease in the paracellular permeability to [H-3]inulin as a function of lo ss of TER. The presence of SA residues on either the apical or basolateral side was determined using a Texas Red-conjugated lectin, wheat germ aggluti nin (WGA), which binds SA residues. WGA bound exclusively to SA residues on the apical surface of the cells, confirming the requirement for SA residue s on the apical cell membrane for efficient infectivity of SA-dependent rot aviruses. These results indicate that the rotavirus SA-independent cellular receptor is present on both sides of the epithelium, but SA-dependent and SA-independent rotavirus strains infect polarized epithelial cells by diffe rent mechanisms, which may be relevant for pathogenesis and selection of va ccine strains. Finally, rotavirus-induced alterations of the epithelial bar rier and paracellular permeability suggest that common mechanisms of pathog enesis may exist between viral and bacterial pathogens of the intestinal tr act.