title: In vitro anti-influenza activity of a protein-enriched fraction from larvae of the housefly (Musca domestica).
abstract: BACKGROUND
  Insects are a large, unexplored and unexploited source of potentially useful compounds for modern medicine. The larvae of the housefly (Musca domestica) have been used to study immune-induced molecules because they can survive in pathogenic environments.
  
  
  OBJECTIVE
  The antiviral activity of a protein-enriched fraction (PEF) from the larvae of the housefly was evaluated in vitro and the possible antiviral mechanism was studied.
  
  
  METHODS
  PEF was isolated from the larvae of the housefly. The cytotoxicity of PEF was detected by the MTT assay. The in vitro antiviral activity of PEF against influenza virus was investigated. PEF was incubated with the virus and its target cells under various conditions, and its antiviral effects were examined by reduction in virus yield in cell cultures. Experiments with ribavirin were performed in parallel under the same conditions.
  
  
  RESULTS
  The results indicated that PEF had minimal cytotoxicity against MDCK cells and the CC₅₀ value was calculated to be 284.45 μg/ml. The antiviral results showed the loss of infectious capacity was more than two log (2) units in cell cultures compared with virus control. The effect of PEF was direct virucidal activity and the interference on the adsorption of cell and virus. The antiviral mechanism of PEF is different from ribavirin.
  
  
  CONCLUSIONS
  The results indicate that PEF showed strong antiviral activity against influenza virus at a very early stage of the interaction with virus particles or their entry into the cells. PEF has a great potential as a resource of healthy products.
authors.affiliation: Institute of Pharmacology, Toxicology and Biochemical Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, PR China. wfr571@yahoo.com.cn
authors.forename: Furong
authors.initials: F
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Ai
authors.forename: Chaoliang
authors.initials: C
authors.lastname: Lei
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000009:adverse effects / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002681:China; D045424:Complex Mixtures / Q000009:adverse effects / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D004285:Dogs; D006389:Hemagglutinins, Viral / Q000378:metabolism; D006793:Houseflies / Q000737:chemistry* / Q000254:growth & development; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects*; D020128:Inhibitory Concentration 50; D019476:Insect Proteins / Q000009:adverse effects / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D007814:Larva / Q000737:chemistry; D061985:Madin Darby Canine Kidney Cells; D053585:Virus Attachment / Q000187:drug effects; D038301:Virus Inactivation / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D045424:Complex Mixtures; D006389:Hemagglutinins, Viral; D019476:Insect Proteins