title: Water extract of Cinnamomum cassia Blume inhibited human respiratory syncytial virus by preventing viral attachment, internalization, and syncytium formation.
abstract: BACKGROUND
  Cinnamomum cassia Blume is a popular traditional Chinese herbal medicine that has been used to manage respiratory tract disease, including common cold and chronic bronchitis for thousand years. Human respiratory syncytial virus (HRSV) is one of the leading causes of severe lower respiratory tract illness worldwide. No effective therapeutic modality against HRSV infection has been proved. It is unknown whether Cinnamomum cassia is effective against HRSV.
  
  
  OBJECTIVE
  This study tested the hypothesis that Cinnamomum cassia can effectively decrease HRSV-induced plaque formation and syncytium formation in respiratory mucosal cell lines.
  
  
  METHODS
  Antiviral activity of the hot water extract of Cinnamomum cassia against HRSV was tested by plaque reduction assay in both human upper (HEp-2) and low (A549) respiratory tract cell lines. Its ability to inhibit the synthesis of viral fusion (F) protein was examined by Western blot assay.
  
  
  RESULTS
  Cinnamomum cassia dose-dependently inhibited HRSV-induced plaque formation in both HEp-2 and A549 cell lines (p<0.0001). Cinnamomum cassia was more effective when given before viral infection (p<0.0001) mainly by inhibition of viral attachment (p<0.0001) and internalization (p<0.0001). Cinnamomum cassia could inhibit F protein production and syncytium formation to interfere with HRSV spreading.
  
  
  CONCLUSIONS
  Cinnamomum cassia prevented airway epithelia from HRSV infection through inhibiting viral attachment, internalization and syncytium formation. Cinnamomum cassia could be a candidate to develop therapeutic modalities to manage HRSV infection in the future.
authors.affiliation: Department of Renal Care, College of Medicine, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan.
authors.forename: Chia Feng
authors.initials: CF
authors.lastname: Yeh
authors.forename: Jung San
authors.initials: JS
authors.lastname: Chang
authors.forename: Kuo Chih
authors.initials: KC
authors.lastname: Wang
authors.forename: Den En
authors.initials: DE
authors.lastname: Shieh
authors.forename: Lien Chai
authors.initials: LC
authors.lastname: Chiang
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D032904:Cinnamomum aromaticum; D015726:Giant Cells / Q000166:cytology / Q000187:drug effects; D006801:Humans; D010936:Plant Extracts / Q000494:pharmacology*; D018547:Plant Stems / Q000737:chemistry; D018113:Respiratory Syncytial Virus, Human / Q000187:drug effects* / Q000502:physiology; D014760:Viral Fusion Proteins / Q000378:metabolism; D010948:Viral Plaque Assay; D053585:Virus Attachment / Q000187:drug effects; D053586:Virus Internalization / Q000187:drug effects; D014867:Water / Q000737:chemistry
chemical_list: D000998:Antiviral Agents; C526850:F protein, human respiratory syncytial virus; D010936:Plant Extracts; D014760:Viral Fusion Proteins; D014867:Water