title: Amaryllidaceae alkaloids inhibit nuclear-to-cytoplasmic export of ribonucleoprotein (RNP) complex of highly pathogenic avian influenza virus H5N1.
abstract: BACKGROUND
  Few drugs are currently licensed to treat influenza A infection, and new therapies are needed, especially for highly pathogenic strains. Traditional medicinal plants, such as Lycoris radiata, are a potential source of new antiviral agents.
  
  
  OBJECTIVE
  To test 15 Amaryllidaceae alkaloids isolated from the bulbs of L. radiata in vitro for antiviral activities against influenza virus type A, A/Chicken/GuangDong/178/2004 (H5N1, 178).
  
  
  METHODS
  Antiviral activities of the compounds were tested in time-of-addition assays, hemagglutination inhibition (HI) assays, neuraminidase (NA) activity assays, and viral entry inhibition assays using H5N1-HIV pseudoviruses. Effects of the compounds on localization and activity of the viral ribonucleoprotein (RNP) were determined by immunofluorescence and an RNP minigenome assay, respectively.
  
  
  RESULTS
  Among the alkaloids, lycorine (AA1), hippeastrine (AA2), hemanthamine (AA3) and 11-hydroxy vittatine (AA4) exhibited antiviral activities, with EC90 values of 0·52, 82·07, 4·15, and 13·45 μm, respectively. These compounds did not affect the function of the outer membrane proteins or the viral entry process and viral RNP activity. As AA1 and AA3 exhibited stronger antiviral activities, they were further analyzed. Intracellular nucleoprotein (NP) localization showed that AA1 and AA3 inhibited the RNP complex in the nucleus at an early stage of a single-round and multi-round of replication.
  
  
  CONCLUSIONS
  Four Amaryllidaceae alkaloids were first determined that could exert anti-influenza activities after virus entry into cells. Furthermore, AA1 and AA3 could inhibit nuclear-to-cytoplasmic export of the RNP complex of virus replication. Thus, these compounds may be developed further as anti-influenza drug candidates.
authors.affiliation: College of Veterinary Medicine, South China Agricultural UniversityKey Laboratory for Animal Vaccine Development, Ministry of AgricultureInstitute of Laboratory Animal, Jinan University GuangzhouCollege of Pharmacy, Jinan UniversityGuangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, Jinan University, Guangzhou, China.
authors.forename: Jun
authors.initials: J
authors.lastname: He
authors.forename: Wen-Bao
authors.initials: WB
authors.lastname: Qi
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Tian
authors.forename: Pei-Rong
authors.initials: PR
authors.lastname: Jiao
authors.forename: Guo-Qian
authors.initials: GQ
authors.lastname: Liu
authors.forename: Wen-Cai
authors.initials: WC
authors.lastname: Ye
authors.forename: Ming
authors.initials: M
authors.lastname: Liao
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects*; D047151:Amaryllidaceae Alkaloids / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D000998:Antiviral Agents / Q000302:isolation & purification / Q000494:pharmacology*; D002460:Cell Line; D002645:Chickens / Q000821:virology; D004285:Dogs; D053124:Influenza A Virus, H5N1 Subtype / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology*; D005585:Influenza in Birds / Q000821:virology; D031426:Lycoris / Q000737:chemistry; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D012367:RNA, Viral / Q000235:genetics; D012261:Ribonucleoproteins / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D047151:Amaryllidaceae Alkaloids; D000998:Antiviral Agents; D012367:RNA, Viral; D012261:Ribonucleoproteins
keywords: Amaryllidaceae alkaloid; H5N1 influenza A virus; vRNP export