Sendai virus efficiently infects cells via the asialoglycoprotein receptor and requires the presence of cleaved F0 precursor proteins for this alternative route of cell entry.

Biochemical evidence suggests that the asialoglycoprotein receptor (ASGP-R) can be used as an alternative receptor for a temperature-sensitive Sendai virus (SV) mutant. We now have investigated this possible alternative route of infection for SV wild-type (SV-wt) strain Fushimi by using a pair of cell lines which differ only with regard to ASGP-R expression. Infection studies after enzymatic destruction of conventional sialic acid-containing SV receptors (SA-R) revealed that only ASGP-R-expressing cells could be infected by SV-wt. This alternative route of cell entry could be completely blocked by incubation of cells with ASGP-R-specific antibodies prior to infection. Furthermore, cleavage of SV-F0 precursor protein into the subunits F1 and F2 was necessary to establish infection via ASGP-R, suggesting a fusion-mediated cell entry after binding of SV-wt to the ASGP-R on host cells. Interestingly, infection via ASGP-R was found to be nearly as efficient as infection via conventional sialic acid-containing SV receptors. A possible physiological role of the ASGP-R-mediated route of SV infection is discussed.