title: Equine alphaherpesviruses (EHV-1 and EHV-4) differ in their efficiency to infect mononuclear cells during early steps of infection in nasal mucosal explants.
abstract: Equine herpesvirus type 1 (EHV-1) replicates extensively in the epithelium of the upper respiratory tract, after which it can spread throughout the body via a cell-associated viremia in mononuclear leukocytes reaching the pregnant uterus and central nervous system. In a previous study, we were able to mimic the in vivo situation in an in vitro respiratory mucosal explant system. A plaquewise spread of EHV-1 was observed in the epithelial cells, whereas in the connective tissue below the basement membrane (BM), EHV-1-infected mononuclear leukocytes were noticed. Equine herpesvirus type 4 (EHV-4), a close relative of EHV-1, can also cause mild respiratory disease, but a cell-associated viremia in leukocytes is scarce and secondary symptoms are rarely observed. Based on this striking difference in pathogenicity, we aimed to evaluate how EHV-4 behaves in equine mucosal explants. Upon inoculation of equine mucosal explants with the EHV-4 strains VLS 829, EQ(1) 012 and V01-3-13, replication of EHV-4 in epithelial cells was evidenced by the presence of viral plaques in the epithelium. Interestingly, EHV-4-infected mononuclear leukocytes in the connective tissue below the BM were extremely rare and were only present for one of the three strains. The inefficient capacity of EHV-4 to infect mononuclear cells explains in part the rarity of EHV-4-induced viremia, and subsequently, the rarity of EHV-4-induced abortion or EHM.
authors.affiliation: Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium. annelies.vandekerckhove@UGent.be
authors.forename: Annelies P
authors.initials: AP
authors.lastname: Vandekerckhove
authors.forename: S
authors.initials: S
authors.lastname: Glorieux
authors.forename: A C
authors.initials: AC
authors.lastname: Gryspeerdt
authors.forename: L
authors.initials: L
authors.lastname: Steukers
authors.forename: J
authors.initials: J
authors.lastname: Van Doorsselaere
authors.forename: N
authors.initials: N
authors.lastname: Osterrieder
authors.forename: G R
authors.initials: GR
authors.lastname: Van de Walle
authors.forename: H J
authors.initials: HJ
authors.lastname: Nauwynck
mesh_terms: D000818:Animals; D004847:Epithelial Cells / Q000821:virology; D006566:Herpesviridae Infections / Q000662:veterinary* / Q000821:virology; D004861:Herpesvirus 1, Equid / Q000472:pathogenicity* / Q000502:physiology; D023141:Herpesvirus 4, Equid / Q000472:pathogenicity* / Q000502:physiology; D006734:Horse Diseases / Q000175:diagnosis / Q000821:virology*; D006736:Horses / Q000821:virology*; D007963:Leukocytes, Mononuclear / Q000821:virology; D009297:Nasal Mucosa / Q000821:virology; D046509:Tissue Culture Techniques; D010948:Viral Plaque Assay / Q000662:veterinary; D056189:Viral Tropism; D014766:Viremia / Q000662:veterinary / Q000821:virology; D014779:Virus Replication