title: The SARS coronavirus spike glycoprotein is selectively recognized by lung surfactant protein D and activates macrophages.
abstract: The severe acute respiratory syndrome coronavirus (SARS-CoV) infects host cells with its surface glycosylated spike-protein (S-protein). Here we expressed the SARS-CoV S-protein to investigate its interactions with innate immune mechanisms in the lung. The purified S-protein was detected as a 210 kDa glycosylated protein. It was not secreted in the presence of tunicamycin and was detected as a 130 kDa protein in the cell lysate. The purified S-protein bound to Vero but not 293T cells and was itself recognized by lung surfactant protein D (SP-D), a collectin found in the lung alveoli. The binding required Ca(2+) and was inhibited by maltose. The serum collectin, mannan-binding lectin (MBL), exhibited no detectable binding to the purified S-protein. S-protein binds and activates macrophages but not dendritic cells (DCs). It suggests that SARS-CoV interacts with innate immune mechanisms in the lung through its S-protein and regulates pulmonary inflammation.
authors.affiliation: Department of Microbiology, National University of Singapore, Singapore.
authors.forename: Rikke
authors.initials: R
authors.lastname: Leth-Larsen
authors.forename: Fei
authors.initials: F
authors.lastname: Zhong
authors.forename: Vincent T K
authors.initials: VT
authors.lastname: Chow
authors.forename: Uffe
authors.initials: U
authors.lastname: Holmskov
authors.forename: Jinhua
authors.initials: J
authors.lastname: Lu
mesh_terms: D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D006801:Humans; D007249:Inflammation / Q000276:immunology; D008168:Lung / Q000276:immunology / Q000473:pathology; D008262:Macrophage Activation / Q000276:immunology*; D008264:Macrophages / Q000276:immunology* / Q000473:pathology; D008562:Membrane Glycoproteins / Q000276:immunology* / Q000378:metabolism; D037663:Pulmonary Surfactant-Associated Protein D / Q000378:metabolism* / Q000502:physiology; D045473:Severe acute respiratory syndrome-related coronavirus / Q000276:immunology* / Q000378:metabolism; D064370:Spike Glycoprotein, Coronavirus; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000276:immunology* / Q000378:metabolism
chemical_list: D008562:Membrane Glycoproteins; D037663:Pulmonary Surfactant-Associated Protein D; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; C578557:spike glycoprotein, SARS-CoV; C578553:spike protein, mouse hepatitis virus