title: Identification of major histocompatibility complex class I C molecule as an attachment factor that facilitates coronavirus HKU1 spike-mediated infection.
abstract: Human coronavirus HKU1 (HCoV-HKU1) is a recently discovered human coronavirus associated with respiratory tract infections worldwide. In this study, we have identified the major histocompatibility complex class I C molecule (HLA-C) as an attachment factor in facilitating HCoV-HKU1 spike (S)-mediated infection. HCoV-HKU1 S pseudotyped virus was assembled using a human immunodeficiency virus type 1-derived reporter virus harboring the human codon-optimized spike of HCoV-HKU1. We identified human alveolar epithelial A549 cells as the most susceptible cell line among those tested to infection by HCoV-HKU1 S pseudotypes. A549 cells were shown to bind purified soluble HCoV-HKU1 S(1-600) glycopeptide. To search for the functional receptor for HCoV-HKU1, an A549 cDNA expression library was constructed and transduced into the nonpermissive, baby hamster kidney cells line BHK-21. Transduced cells that bind soluble HCoV-HKU1 S(1-600) glycoprotein with C-terminal FLAG were sorted. Sequencing of two independent clones revealed cDNA inserts encoding HLA-C. Inhibition of HLA-C expression or function by RNAi silencing and anti-HLA-C antibody decreased HCoV-HKU1 S pseudotyped virus infection of A549 cells by 62 to 65%, whereas pretreatment of cells with neuraminidase decreased such infection by only 13%. When HLA-C was constitutively expressed in another nonpermissive cell line, NIH-3T3, quantitative PCR showed that the binding of HCoV-HKU1 S pseudotyped virus to cell surfaces was increased by 200-fold, but the cells remained nonsusceptible to HCoV-HKU1 S pseudotyped virus infection. Our data suggest that HLA-C is involved in the attachment of HCoV-HKU1 to A549 cells and is a potential candidate to facilitate cell entry. However, other unknown surface proteins on A549 cells may be concomitantly utilized by S glycoprotein of HCoV-HKU1 during viral entry. Further studies are required to elucidate other putative receptors or coreceptors for HCoV-HKU1 and the mechanism of HCoV-HKU1 S-mediated cell entry.
authors.affiliation: Department of Microbiology, The University of Hong Kong, Hong Kong.
authors.forename: Che Man
authors.initials: CM
authors.lastname: Chan
authors.forename: Susanna K P
authors.initials: SK
authors.lastname: Lau
authors.forename: Patrick C Y
authors.initials: PC
authors.lastname: Woo
authors.forename: Herman
authors.initials: H
authors.lastname: Tse
authors.forename: Bo-Jian
authors.initials: BJ
authors.lastname: Zheng
authors.forename: Ling
authors.initials: L
authors.lastname: Chen
authors.forename: Jian-Dong
authors.initials: JD
authors.lastname: Huang
authors.forename: Kwok-Yung
authors.initials: KY
authors.lastname: Yuen
mesh_terms: D000818:Animals; D002460:Cell Line; D017934:Coronavirus / Q000502:physiology*; D006224:Cricetinae; D004847:Epithelial Cells / Q000821:virology; D020868:Gene Silencing; D015236:HLA-C Antigens / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D011991:Receptors, Virus / Q000235:genetics / Q000378:metabolism*; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins / Q000378:metabolism*; D053585:Virus Attachment
chemical_list: D015236:HLA-C Antigens; D008562:Membrane Glycoproteins; D011991:Receptors, Virus; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins