Endonuclease activity inhibition of the NS1 protein of parvovirus B19 as a novel target for antiviral drug development

Peng Xu, Safder S. Ganaie, Xiaomei Wang, Zekun Wang, Steve Kleiboeker, Nancy C. Horton, Richard F. Heier, Marvin J. Meyers, John E. Tavis, Jianming Qiu

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Human parvovirus B19 (B19V), a member of the genus Erythroparvovirus of the family Parvoviridae, is a small nonenveloped virus that has a single-stranded DNA (ssDNA) genome of 5.6 kb with two inverted terminal repeats (ITRs). B19V infection often results in severe hematological disorders and fetal death in humans. B19V replication follows a model of rolling hairpin-dependent DNA replication, in which the large nonstructural protein NS1 introduces a site-specific single-strand nick in the viral DNA replication origins, which locate at the ITRs. NS1 executes endonuclease activity through the N-terminal origin-binding domain. Nicking of the viral replication origin is a pivotal step in rolling hairpin-dependent viral DNA replication. Here, we developed a fluorophore-based in vitro nicking assay of the replication origin using the origin-binding domain of NS1 and compared it with the radioactive in vitro nicking assay. We used both assays to screen a set of small-molecule compounds (n 96) that have potential antinuclease activity. We found that the fluorophore-based in vitro nicking assay demonstrates sensitivity and specificity values as high as those of the radioactive assay. Among the 96 compounds, we identified 8 which have an inhibition of 80% at 10 M in both the fluorophore-based and radioactive in vitro nicking assays. We further tested 3 compounds that have a flavonoid-like structure and an in vitro 50% inhibitory concentration that fell in the range of 1 to 3 M. Importantly, they also exhibited inhibition of B19V DNA replication in UT7/Epo-S1 cells and ex vivo-expanded human erythroid progenitor cells.

Original languageEnglish (US)
Article numbere01879-18
JournalAntimicrobial Agents and Chemotherapy
Issue number3
StatePublished - Mar 2019


  • Antivirals
  • In vitro nicking assay
  • Parvovirus B19

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases


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