Invading viral DNA triggers dsRNA synthesis by RNA polymerase II to activate antiviral RNA interference in Drosophila

Isaque J.S. de Faria, Eric R.G.R. Aguiar, Roenick P. Olmo, Juliana Alves da Silva, Laurent Daeffler, Richard W. Carthew, Jean Luc Imler, João T. Marques*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

dsRNA sensing triggers antiviral responses against RNA and DNA viruses in diverse eukaryotes. In Drosophila, Invertebrate iridescent virus 6 (IIV-6), a large DNA virus, triggers production of small interfering RNAs (siRNAs) by the dsRNA sensor Dicer-2. Here, we show that host RNA polymerase II (RNAPII) bidirectionally transcribes specific AT-rich regions of the IIV-6 DNA genome to generate dsRNA. Both replicative and naked IIV-6 genomes trigger production of dsRNA in Drosophila cells, implying direct sensing of invading DNA. Loquacious-PD, a Dicer-2 co-factor essential for the biogenesis of endogenous siRNAs, is dispensable for processing of IIV-6-derived dsRNAs, which suggests that they are distinct. Consistent with this finding, inhibition of the RNAPII co-factor P-TEFb affects the synthesis of endogenous, but not virus-derived, dsRNA. Altogether, our results suggest that a non-canonical RNAPII complex recognizes invading viral DNA to synthesize virus-derived dsRNA, which activates the antiviral siRNA pathway in Drosophila.

Original languageEnglish (US)
Article number110976
JournalCell reports
Volume39
Issue number12
DOIs
StatePublished - Jun 21 2022

Funding

We would like to thank all members of the Marques and Imler laboratories for invaluable assistance and discussions. We also thank Phillip D. Zamore for mutant flies, the Sequencing Platform of Strasbourg (University of Strasbourg) for high-throughput sequencing, and the UFMG microscopy facility (CAPI) for image acquisition. This work of the Interdisciplinary Thematic Institute IMCBio , as part of the ITI 2021-2028 program of the University of Strasbourg , CNRS , and Inserm , was supported by IdEx Unistra ( ANR-10-IDEX-0002 ), by the SFRI-STRAT’US project ( ANR 20-SFRI-0012 ), and by EUR IMCBio ( IMCBio ANR-17-EURE-0023 ) under the framework of the French Investments for the Future Program as well as by the previous Labex NetRNA ( ANR-10-LABX-0036 ). This work has also been supported by grants from the Conselho Nacional de Desenvolvimento Científico e Tecnológico , Fundação de Amparo à Pesquisa do Estado de Minas Gerais , Rede Mineira de Imunobiológicos (grant REDE-00140-16 ), Rede Mineira de Biomoléculas (grant REDE-00125-16 ), Instituto Nacional de Ciência e Tecnologia de Vacinas (INCTV) , Institute for Advanced Studies of the University of Strasbourg (USIAS Fellowship 2019), and Fonds régionale de coopération pour la recherche FRCT2020 Région Grand-Est (ViroMod) to J.T.M. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -Brasil (CAPES) - Finance Code 001 to J.T.M. I.S.J.F. was supported by fellowships from CNPq and CAPES . R.W.C. was supported by the NIH ( R35GM118144 ).

Keywords

  • CP: Immunology
  • DNA sensing
  • antiviral RNAi
  • dsRNA
  • invertebrate immunity

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology

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