Human coronavirus 229E can use CD209L (L-SIGN) to enter cells.

The primary receptor for SARS-CoV is ACE2, a metallopeptidase expressed on membranes of renal and cardiovascular tissues as well as the gastrointestinal tract. Marzi et al., showed that retroviral pseudotypes bearing the SARS-CoV glycoprotein could also bind to DC-SIGN and CD209L (also called L-SIGN or DC-SIGNR) on cell membranes, but not use these C-type lectins to enter cells. We showed that CD209L, which is expressed on sinusoidal endothelial cells of the liver, endothelial cells of the lymph nodes, Peyer’s patches, capillaries in the villous lamina propria of the terminal ileum, and in type II alveolar cells and endothelial cells in the lung, has receptor activity for SARS-CoV. Briefly, Chinese hamster ovary (CHO) cells, which are refractory to binding of SARS-CoV spike glycoprotein and entry of SARS-CoV, were transduced with a human lung cDNA library in a retroviral vector. Cells that bound soluble SARS-CoV spike glycoprotein were detected by flow cytometry and inoculated with SARS-CoV under BSL-3 conditions. Virus entry and viral subgenomic RNA and protein synthesis were detected by RT-PCR and immunofluorescence. Less than 1% of the cells expressed SARS-CoV nucleocapsid protein 24 hours after inoculation. CD209L cDNA was cloned from subcloned cells positive for both binding of SARS-CoV spike and expression of SARS-CoV subgenomic RNA and N protein. Transfection of CHO cells with cDNA encoding CD209L made these cells as susceptible to SARS-CoV as the retrovirus transduced cells. DC-SIGN on dendritic cells has been shown to act as an attachment factor for Ebola virus, HIV-1, and other enveloped viruses. The dendritic cells, which are professional antigen-presenting cells, can present virus to macrophages or CD4 T-cells that express the appropriate receptor (CD4 and co-receptors for HIV-1). Thus DC-SIGN is said to mediate infection in trans. Our data suggest that CD209L may act as an alternative weak receptor for SARSCoV. Coronaviruses bud from the ER-Golgi intermediate compartment (ERGIC) and are believed to be released from cells by exocytosis. 9 The maturation of virus in the ERGIC