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Caractérisation des interactions entre les défenses antivirales et le contrôle génomique des éléments transposables chez Drosophila

Abstract : Transposable elements (TEs) are genomic parasites that are found in all genomes, a part of which display structure similarity to some viruses. In insect ovarian cells, TE transcript abundance is controlled by RNA interference (RNAi) machinery and more particularly by the piRNA pathway (Piwi-interacting RNA). Another RNAi pathway, named siRNA pathway (Small interfering RNA), is one of the key insect immune responses against viral infections and is also dedicated to TE somatic control. These two interfering RNA pathways are led by distinct molecular effectors and described as independent. However, similarities in structure and control mechanisms across TEs and viruses suggest that an interplay may exist. We used Drosophila as a model, and infected the organism with Sindbis virus (SINV), an arbovirus (Arthropod-Borne virus), or Sigma virus (SV), a Drosophila-specific virus. Using high-throughput sequencing, we characterized the RNA and small-RNA repertoires produced by Drosophila flies from carcass or ovary tissues. Overall, our results demonstrate an impact of viral infection on TE transcript amounts via modulation of the piRNA and siRNA repertoires and represent the first demonstration of the effects of viral infection on TE activity. More precisely, SINV infection promotes a global decrease of TE transcript levels while SV infection reactivates many TEs. Our data suggest that the modulation results from shared RNA substrates and common trans-regulators of the small RNA pathways. These results open new avenue of research in genomics, suggesting that viral epidemics or chronic infections can impact TE activity and thus the rate of subsequent genetic diversification
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https://tel.archives-ouvertes.fr/tel-02943888
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  • HAL Id : tel-02943888, version 1

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Marlène Roy. Caractérisation des interactions entre les défenses antivirales et le contrôle génomique des éléments transposables chez Drosophila. Virologie. Université de Lyon, 2019. Français. ⟨NNT : 2019LYSE1126⟩. ⟨tel-02943888⟩

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