title: Alveolar macrophages are the main target cells in feline calicivirus-associated pneumonia.
abstract: Feline calicivirus (FCV) is a pathogen of felids and one of the most common causative agents of feline upper respiratory disease (URD). Reports of natural FCV pneumonia in the course of respiratory tract infections are sparse. Therefore, knowledge on the pathogenesis of FCV-induced lung lesions comes only from experimental studies. The aim of the present study was to assess the type and extent of pulmonary involvement in natural respiratory FCV infections of domestic cats and to identify the viral target cells in the lung. For this purpose, histology, immunohistochemistry and RNA-in situ hybridisation for FCV and relevant cell markers were performed on diagnostic post-mortem specimens collected after fatal URD, virulent systemic FCV or other conditions. All groups of cats exhibited similar acute pathological changes, dominated by multifocal desquamation of activated alveolar macrophages (AM) and occasional type II pneumocytes with fibrin exudation, consistent with diffuse alveolar damage (DAD). In fatal cases, this was generally seen without evidence of epithelial regeneration. In cats without clinical respiratory signs, type II pneumocyte hyperplasia was present alongside the other changes, consistent with the post-damage proliferative phase of DAD. FCV infected and replicated in AM and, to a lesser extent, type II pneumocytes. This study shows that lung involvement is an infrequent but important feature of FCV-induced URD. AM are the main viral target cell and pulmonary replication site, and their infection is associated with desquamation and activation, as well as death via apoptosis.
authors.affiliation: Veterinary Pathology, School of Veterinary Science, University of Liverpool, Leahurst Campus, Chester High Road, Neston CH64 7TE, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Monné Rodriguez
authors.affiliation: Veterinary Pathology, School of Veterinary Science, University of Liverpool, Leahurst Campus, Chester High Road, Neston CH64 7TE, UK; University of Agricultural Sciences and Veterinary Medicine, Splaiul Independentei 105, 050097 Bucharest, Romania.
authors.forename: T
authors.initials: T
authors.lastname: Soare
authors.affiliation: Veterinary Pathology, School of Veterinary Science, University of Liverpool, Leahurst Campus, Chester High Road, Neston CH64 7TE, UK.
authors.forename: A
authors.initials: A
authors.lastname: Malbon
authors.affiliation: Veterinary Pathology, School of Veterinary Science, University of Liverpool, Leahurst Campus, Chester High Road, Neston CH64 7TE, UK; Department of Infection Biology, Institute of Global Health, University of Liverpool, Liverpool Science Park IC2, 146 Brownlow Hill, Liverpool L3 5RF, UK.
authors.forename: R
authors.initials: R
authors.lastname: Blundell
authors.affiliation: Veterinary Pathology, School of Veterinary Science, University of Liverpool, Leahurst Campus, Chester High Road, Neston CH64 7TE, UK; Department of Infection Biology, Institute of Global Health, University of Liverpool, Liverpool Science Park IC2, 146 Brownlow Hill, Liverpool L3 5RF, UK.
authors.forename: R
authors.initials: R
authors.lastname: Papoula-Pereira
authors.affiliation: Veterinary Pathology, School of Veterinary Science, University of Liverpool, Leahurst Campus, Chester High Road, Neston CH64 7TE, UK; Department of Infection Biology, Institute of Global Health, University of Liverpool, Liverpool Science Park IC2, 146 Brownlow Hill, Liverpool L3 5RF, UK.
authors.forename: G
authors.initials: G
authors.lastname: Leeming
authors.affiliation: Institute of Veterinary Pathology, Faculty of Veterinary Medicine, University of Giessen, Frankfurter Strasse 96, 35393 Giessen, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Köhler
authors.affiliation: Veterinary Pathology, School of Veterinary Science, University of Liverpool, Leahurst Campus, Chester High Road, Neston CH64 7TE, UK; Department of Infection Biology, Institute of Global Health, University of Liverpool, Liverpool Science Park IC2, 146 Brownlow Hill, Liverpool L3 5RF, UK; Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Winterthurer Strasse 268, 8057 Zurich, Switzerland. Electronic address: anja.kipar@uzh.ch.
authors.forename: A
authors.initials: A
authors.lastname: Kipar
mesh_terms: D000818:Animals; D017250:Caliciviridae Infections / Q000662:veterinary* / Q000821:virology; D017927:Calicivirus, Feline / Q000302:isolation & purification / Q000502:physiology*; D002371:Cat Diseases / Q000821:virology*; D002415:Cats; D005260:Female; D007150:Immunohistochemistry / Q000662:veterinary; D017403:In Situ Hybridization / Q000662:veterinary; D016676:Macrophages, Alveolar / Q000821:virology*; D008297:Male; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012367:RNA, Viral / Q000032:analysis; D012141:Respiratory Tract Infections / Q000662:veterinary* / Q000821:virology; D014774:Virulence
chemical_list: D012367:RNA, Viral
keywords: Alveolar macrophages; Feline calicivirus; Immunohistochemistry; Pulmonary infection; RNA-in situ hybridisation