title: Ching-fang-pai-tu-san inhibits the release of influenza virus.
abstract: BACKGROUND
  Ching-fang-pai-tu-san (CFPTS) is a Chinese herbal decoction that is used as a cure for the common cold, fever, headache, and poor circulation. However, no previous studies have investigated the mode of action of CFPTS against influenza virus infections. To investigate the antiviral mechanism of CFPTS, we examined viral entry, transcription, translation, viral glycoprotein hemagglutinin (HA) transport, and budding of the influenza virus.
  
  
  METHODS
  The antiviral activity of nontoxic concentrations of CFPTS against influenza virus A/WSN/33 was examined by assaying (neutralization assay) its inhibition of the virus-induced cytopathic effects. The mode of CFPTS action was first examined with a time-of-addition assay of synchronized infections, followed by monitoring HA transport by immunofluorescence microscopy. Viral endocytosis was evaluated with attachment and penetration assays. The inhibition of viral replication was measured by quantitative real-time PCR, immunoblotting, and immunofluorescence microscopy. We also performed assays related to the inhibition of viral entry, such as neuraminidase activity and hemagglutinin activity assays.
  
  
  RESULTS
  Based on the inhibition of the virus-induced cytopathic effect in Madin-Darby canine kidney cells, the EC(50) of CFPTS was about 1.44 ± 0.22 mg/mL against influenza virus A/WSN/33. CFPTS displayed a broad spectrum of inhibitory activities against different strains of influenza A virus, as well as some enteroviruses. However, this extract proved less effective against clinical oseltamivir-resistant strains and influenza B viruses. CFPTS did not suppress viral RNA or protein synthesis. According to a time-of-addition assay, the antiviral mechanism of CFPTS may involve viral budding or intracellular viral glycoprotein transport. A plaque reduction assay showed that CFPTS reduced both the plaque size and plaque quantity. The intracellular transport of viral glycoprotein hemagglutinin was blocked by CFPTS by immunofluorescence microscopic analysis. Thus, it is possible that the antiviral mechanism of CFPTS might inhibit the assembly of progeny virions and/or their subsequent release.
  
  
  CONCLUSIONS
  Our results give scientific support to the use of CFPTS in the treatment of influenza virus infections. CFPTS has potential utility in the management of seasonal pandemics of influenza virus infections, like other clinically available drugs.
authors.affiliation: Graduate Institute of Biomedical Sciences, Chang Gung University, Kweishan, Taoyuan 333, Taiwan.
authors.forename: Chung-Fan
authors.initials: CF
authors.lastname: Hsieh
authors.forename: Hung-Rong
authors.initials: HR
authors.lastname: Yen
authors.forename: Chih-Hao
authors.initials: CH
authors.lastname: Liu
authors.forename: Shiming
authors.initials: S
authors.lastname: Lin
authors.forename: Jim-Tong
authors.initials: JT
authors.lastname: Horng
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004285:Dogs; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004770:Enterovirus / Q000187:drug effects / Q000472:pathogenicity; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000378:metabolism*; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D009975:Orthomyxoviridae / Q000187:drug effects* / Q000472:pathogenicity / Q000502:physiology; D014176:Protein Biosynthesis / Q000187:drug effects; D012367:RNA, Viral / Q000378:metabolism; D010948:Viral Plaque Assay; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D004365:Drugs, Chinese Herbal; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D012367:RNA, Viral; C580913:ching-fang-pai-tu-san