title: Inhibitory effects of indigowoad root polysaccharides on porcine reproductive and respiratory syndrome virus replication in vitro.
abstract: BACKGROUND
  Indigowoad root polysaccharide (IRPS) is a natural polysaccharide isolated from the traditional Chinese medicinal herb Radix Isatidis, and has many kinds of biological activities. However, the IRPS antiviral activity, especially the anti-porcine reproductive and respiratory syndrome virus (PRRSV) effect, has not been evaluated.
  
  
  METHODS
  PRRSV was propagated in the MARC-145 cell line, and viral titre was determined by cytopathic effect and expressed as the 50% tissue culture infection dose (TCID(50)) in the current study. The cell cytotoxic effect of IRPS toward MARC-145 was evaluated by MTT assay firstly, then the inhibitory effects of IRPS on PRRSV replication in vitro were investigated by determining the effect of IRPS upon a single replicative cycle of PRRSV in MARC-145 cells. The effects of IRPS on viral RNA and protein synthesis in PRRSV-infected cells were investigated using real-time PCR and double-antibody (sandwich) ELISA.
  
  
  RESULTS
  IRPS was able to effectively suppress the infectivity of the PRRSV in a dose-dependent manner, especially by adding IRPS during the PRRSV infection. IRPS could affect the attachment of PRRSV to MARC-145 cells, and also inhibit the viral RNA and protein synthesis.
  
  
  CONCLUSIONS
  IRPS has an antiviral effect on PRRSV replication in MARC-145 cells and might be useful in medical development for antiviral research. However, the precise mechanism of the host and viral targets of IRPS are unknown, so further studies should be conducted to investigate the precise mechanism of IRPS inhibitory effect on PRRSV infection.
authors.affiliation: The College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, People's Republic of China.
authors.forename: Zhan-Yong
authors.initials: ZY
authors.lastname: Wei
authors.forename: Xue-Bing
authors.initials: XB
authors.lastname: Wang
authors.forename: Hong-Ying
authors.initials: HY
authors.lastname: Zhang
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Yang
authors.forename: Ya-Bin
authors.initials: YB
authors.lastname: Wang
authors.forename: Duan-Hong
authors.initials: DH
authors.lastname: Xu
authors.forename: Hong-Ying
authors.initials: HY
authors.lastname: Chen
authors.forename: Bao-An
authors.initials: BA
authors.lastname: Cui
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D002460:Cell Line; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D031219:Isatis / Q000737:chemistry*; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000821:virology; D008516:Medicine, Chinese Traditional; D018517:Plant Roots / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D019316:Porcine respiratory and reproductive syndrome virus / Q000187:drug effects* / Q000502:physiology; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D004365:Drugs, Chinese Herbal; D011134:Polysaccharides