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PMCID: PMC5354443 DOI: 10.1371/journal.ppat.1006266


Human parvovirus B19 (B19V) infection of primary human erythroid progenitor cells (EPCs) arrests infected cells at both late S-phase and G2-phase, which contain 4N DNA. B19V infection induces a DNA damage response (DDR) that facilitates viral DNA replication but is dispensable for cell cycle arrest at G2-phase; however, a putative C-terminal transactivation domain (TAD2) within NS1 is responsible for G2-phase arrest. To fully understand the mechanism underlying B19V NS1-induced G2-phase arrest, we established two doxycycline-inducible B19V-permissive UT7/Epo-S1 cell lines that express NS1 or NS1mTAD2, and examined the function of the TAD2 domain during G2-phase arrest. The results confirm that the NS1 TAD2 domain plays a pivotal role in NS1-induced G2-phase arrest. Mechanistically, NS1 transactivated cellular gene expression through the TAD2 domain, which was itself responsible for ATR (ataxia-telangiectasia mutated and Rad3-related) activation. Activated ATR phosphorylated CDC25C at serine 216, which in turn inactivated the cyclin B/CDK1 complex without affecting nuclear import of the complex. Importantly, we found that the ATR-CHK1-CDC25C-CDK1 pathway was activated during B19V infection of EPCs, and that ATR activation played an important role in B19V infection-induced G2-phase arrest.

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PLoS Pathog





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MeSH Keywords

Ataxia Telangiectasia Mutated Proteins; Blotting, Western; CDC2 Protein Kinase; Cell Line; Cyclin-Dependent Kinases; Erythroid Precursor Cells; Flow Cytometry; G2 Phase Cell Cycle Checkpoints; Humans; Immunoprecipitation; Oligonucleotide Array Sequence Analysis; Parvoviridae Infections; Parvovirus B19, Human; Signal Transduction; Viral Nonstructural Proteins; cdc25 Phosphatases