title: Role of sialic acids in feline enteric coronavirus infections.
abstract: To initiate infections, many coronaviruses use sialic acids, either as receptor determinants or as attachment factors helping the virus find its receptor underneath the heavily glycosylated mucus layer. In the present study, the role of sialic acids in serotype I feline enteric coronavirus (FECV) infections was studied in feline intestinal epithelial cell cultures. Treatment of cells with neuraminidase (NA) enhanced infection efficiency, showing that terminal sialic acid residues on the cell surface were not receptor determinants and even hampered efficient virus-receptor engagement. Knowing that NA treatment of coronaviruses can unmask viral sialic acid binding activity, replication of untreated and NA-treated viruses was compared, showing that NA treatment of the virus enhanced infectivity in untreated cells, but was detrimental in NA-treated cells. By using sialylated compounds as competitive inhibitors, it was demonstrated that sialyllactose (2,6-α-linked over 2,3-α-linked) notably reduced infectivity of NA-treated viruses, whereas bovine submaxillary mucin inhibited both treated and untreated viruses. In desialylated cells, however, viruses were less prone to competitive inhibition with sialylated compounds. In conclusion, this study demonstrated that FECV had a sialic acid binding capacity, which was partially masked by virus-associated sialic acids, and that attachment to sialylated compounds could facilitate enterocyte infections. However, sialic acid binding was not a prerequisite for the initiation of infection and virus-receptor engagement was even more efficient after desialylation of cells, indicating that FECV requires sialidases for efficient enterocyte infections.
authors.affiliation: Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Lowiese M B
authors.initials: LMB
authors.lastname: Desmarets
authors.affiliation: Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Sebastiaan
authors.initials: S
authors.lastname: Theuns
authors.affiliation: Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Inge D M
authors.initials: IDM
authors.lastname: Roukaerts
authors.affiliation: Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Delphine D
authors.initials: DD
authors.lastname: Acar
authors.affiliation: Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Nauwynck
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000821:virology; D002415:Cats; D002460:Cell Line; D018352:Coronavirus Infections / Q000821:virology; D016765:Coronavirus, Feline / Q000276:immunology*; D004847:Epithelial Cells / Q000821:virology; D016766:Feline Infectious Peritonitis / Q000821:virology; D060748:Fetuins / Q000494:pharmacology; D005752:Gastric Mucins / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000821:virology; D007781:Lactoferrin / Q000494:pharmacology; D007785:Lactose / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D009439:Neuraminidase / Q000494:pharmacology*; D011991:Receptors, Virus / Q000037:antagonists & inhibitors*; D012794:Sialic Acids / Q000378:metabolism* / Q000494:pharmacology; D053585:Virus Attachment / Q000187:drug effects*
chemical_list: D060748:Fetuins; D005752:Gastric Mucins; D011991:Receptors, Virus; D012794:Sialic Acids; C000020:N-acetylneuraminoyllactose; D009439:Neuraminidase; D007781:Lactoferrin; D007785:Lactose