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PLoS Pathog. 2014 Feb 6;10(2):e1003904. doi: 10.1371/journal.ppat.1003904. eCollection 2014 Feb.

The master regulator of the cellular stress response (HSF1) is critical for orthopoxvirus infection.

Author information

1
Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America ; United States Army Medical Research Institute of Infectious Diseases, Virology Division, Fort Detrick, Maryland, United States of America.
2
Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts, United States of America.
3
Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, United States of America.
4
The Broad Institute, Cambridge Massachusetts, United States of America.
5
United States Army Medical Research Institute of Infectious Diseases, Virology Division, Fort Detrick, Maryland, United States of America.

Abstract

The genus Orthopoxviridae contains a diverse group of human pathogens including monkeypox, smallpox and vaccinia. These viruses are presumed to be less dependent on host functions than other DNA viruses because they have large genomes and replicate in the cytoplasm, but a detailed understanding of the host factors required by orthopoxviruses is lacking. To address this topic, we performed an unbiased, genome-wide pooled RNAi screen targeting over 17,000 human genes to identify the host factors that support orthopoxvirus infection. We used secondary and tertiary assays to validate our screen results. One of the strongest hits was heat shock factor 1 (HSF1), the ancient master regulator of the cytoprotective heat-shock response. In investigating the behavior of HSF1 during vaccinia infection, we found that HSF1 was phosphorylated, translocated to the nucleus, and increased transcription of HSF1 target genes. Activation of HSF1 was supportive for virus replication, as RNAi knockdown and HSF1 small molecule inhibition prevented orthopoxvirus infection. Consistent with its role as a transcriptional activator, inhibition of several HSF1 targets also blocked vaccinia virus replication. These data show that orthopoxviruses co-opt host transcriptional responses for their own benefit, thereby effectively extending their functional genome to include genes residing within the host DNA. The dependence on HSF1 and its chaperone network offers multiple opportunities for antiviral drug development.

PMID:
24516381
PMCID:
PMC3916389
DOI:
10.1371/journal.ppat.1003904
[Indexed for MEDLINE]
Free PMC Article

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