title: Activation of COX-2/PGE2 Promotes Sapovirus Replication via the Inhibition of Nitric Oxide Production.
abstract: Enteric caliciviruses in the genera Norovirus and Sapovirus are important pathogens that cause severe acute gastroenteritis in both humans and animals. Cyclooxygenases (COXs) and their final product, prostaglandin E2(PGE2), are known to play important roles in the modulation of both the host response to infection and the replicative cycles of several viruses. However, the precise mechanism(s) by which the COX/PGE2pathway regulates sapovirus replication remains largely unknown. In this study, infection with porcine sapovirus (PSaV) strain Cowden, the only cultivable virus within the genus Sapovirus, markedly increased COX-2 mRNA and protein levels at 24 and 36 h postinfection (hpi), with only a transient increase in COX-1 levels seen at 24 hpi. The treatment of cells with pharmacological inhibitors, such as nonsteroidal anti-inflammatory drugs or small interfering RNAs (siRNAs) against COX-1 and COX-2, significantly reduced PGE2production, as well as PSaV replication. Expression of the viral proteins VPg and ProPol was associated with activation of the COX/PGE2pathway. We observed that pharmacological inhibition of COX-2 dramatically increased NO production, causing a reduction in PSaV replication that could be restored by inhibition of nitric oxide synthase via the inhibitor N-nitro-l-methyl-arginine ester. This study identified a pivotal role for the COX/PGE2pathway in the regulation of NO production during the sapovirus life cycle, providing new insights into the life cycle of this poorly characterized family of viruses. Our findings also reveal potential new targets for treatment of sapovirus infection.
  
  
  OBJECTIVE
  Sapoviruses are among the major etiological agents of acute gastroenteritis in both humans and animals, but little is known about sapovirus host factor requirements. Here, using only cultivable porcine sapovirus (PSaV) strain Cowden, we demonstrate that PSaV induced the vitalization of the cyclooxygenase (COX) and prostaglandin E2(PGE2) pathway. Targeting of COX-1/2 using nonsteroidal anti-inflammatory drugs (NSAIDs) such as the COX-1/2 inhibitor indomethacin and the COX-2-specific inhibitors NS-398 and celecoxib or siRNAs targeting COXs, inhibited PSaV replication. Expression of the viral proteins VPg and ProPol was associated with activation of the COX/PGE2pathway. We further demonstrate that the production of PGE2provides a protective effect against the antiviral effector mechanism of nitric oxide. Our findings uncover a new mechanism by which PSaV manipulates the host cell to provide an environment suitable for efficient viral growth, which in turn can be a new target for treatment of sapovirus infection.
authors.affiliation: Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Mia Madel
authors.initials: MM
authors.lastname: Alfajaro
authors.affiliation: Division of Life Science, Korea Basic Science Institute, Seoul, Republic of Korea.
authors.forename: Jong-Soon
authors.initials: JS
authors.lastname: Choi
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Deok-Song
authors.initials: DS
authors.lastname: Kim
authors.affiliation: Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Ja-Young
authors.initials: JY
authors.lastname: Seo
authors.affiliation: Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Ji-Yun
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Jun-Gyu
authors.initials: JG
authors.lastname: Park
authors.affiliation: Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Soliman
authors.affiliation: Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Yeong-Bin
authors.initials: YB
authors.lastname: Baek
authors.affiliation: Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Eun-Hyo
authors.initials: EH
authors.lastname: Cho
authors.affiliation: Division of Life Science, Korea Basic Science Institute, Seoul, Republic of Korea.
authors.forename: Joseph
authors.initials: J
authors.lastname: Kwon
authors.affiliation: Bioindustry Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea.
authors.forename: Hyung-Jun
authors.initials: HJ
authors.lastname: Kwon
authors.affiliation: Bioindustry Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea.
authors.forename: Su-Jin
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Bioindustry Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea.
authors.forename: Woo Song
authors.initials: WS
authors.lastname: Lee
authors.affiliation: Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Mun-Il
authors.initials: MI
authors.lastname: Kang
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Myra
authors.initials: M
authors.lastname: Hosmillo
authors.affiliation: Division of Virology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom ig299@cam.ac.uk choko@chonnam.ac.kr.
authors.forename: Ian
authors.initials: I
authors.lastname: Goodfellow
authors.affiliation: Laboratory of Veterinary Pathology, College of Veterinary Medicine, Chonnam National University, Gwangju, Republic of Korea ig299@cam.ac.uk choko@chonnam.ac.kr.
authors.forename: Kyoung-Oh
authors.initials: KO
authors.lastname: Cho
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000494:pharmacology; D017250:Caliciviridae Infections / Q000235:genetics / Q000378:metabolism* / Q000821:virology*; D002460:Cell Line; D002478:Cells, Cultured; D051545:Cyclooxygenase 1 / Q000235:genetics / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000378:metabolism*; D015870:Gene Expression; D009569:Nitric Oxide / Q000096:biosynthesis*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D029341:Sapovirus / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects; D013552:Swine; D014779:Virus Replication / Q000187:drug effects
chemical_list: D001647:Bile Acids and Salts; D052246:Cyclooxygenase 2 Inhibitors; D034741:RNA, Small Interfering; D009569:Nitric Oxide; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D015232:Dinoprostone
keywords: caliciviruses; cyclooxygenases; nitric oxide; prostaglandin E2; sapovirus