title: Neuraminidase activity provides a practical read-out for a high throughput influenza antiviral screening assay.
abstract: BACKGROUND
  The emergence of influenza strains that are resistant to commonly used antivirals has highlighted the need to develop new compounds that target viral gene products or host mechanisms that are essential for effective virus replication. Existing assays to identify potential antiviral compounds often use high throughput screening assays that target specific viral replication steps. To broaden the search for antivirals, cell-based replication assays can be performed, but these are often labor intensive and have limited throughput.
  
  
  RESULTS
  We have adapted a traditional virus neutralization assay to develop a practical, cell-based, high throughput screening assay. This assay uses viral neuraminidase (NA) as a read-out to quantify influenza replication, thereby offering an assay that is both rapid and sensitive. In addition to identification of inhibitors that target either viral or host factors, the assay allows simultaneous evaluation of drug toxicity. Antiviral activity was demonstrated for a number of known influenza inhibitors including amantadine that targets the M2 ion channel, zanamivir that targets NA, ribavirin that targets IMP dehydrogenase, and bis-indolyl maleimide that targets protein kinase A/C. Amantadine-resistant strains were identified by comparing IC50 with that of the wild-type virus.
  
  
  CONCLUSIONS
  Antivirals with specificity for a broad range of targets are easily identified in an accelerated viral inhibition assay that uses NA as a read-out of replication. This assay is suitable for high throughput screening to identify potential antivirals or can be used to identify drug-resistant influenza strains.
authors.affiliation: Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA. Maryna.Eichelberger@fda.hhs.gov
authors.forename: Maryna C
authors.initials: MC
authors.lastname: Eichelberger
authors.forename: Arash
authors.initials: A
authors.lastname: Hassantoufighi
authors.forename: Meng
authors.initials: M
authors.lastname: Wu
authors.forename: Min
authors.initials: M
authors.lastname: Li
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002642:Chick Embryo; D004353:Drug Evaluation, Preclinical; D024882:Drug Resistance, Viral; D004372:Ducks; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D009980:Influenza A virus / Q000187:drug effects* / Q000201:enzymology; D009981:Influenza B virus / Q000187:drug effects* / Q000201:enzymology; D007251:Influenza, Human / Q000188:drug therapy* / Q000821:virology; D009439:Neuraminidase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D014764:Viral Proteins; D009439:Neuraminidase