Comparative genomics shows that viral integrations are abundant and express piRNAs in the arboviral vectors Aedes aegypti and Aedes albopictusReportar como inadecuado

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BMC Genomics

, 18:512

Multicellular invertebrate genomics


BackgroundArthropod-borne viruses arboviruses transmitted by mosquito vectors cause many important emerging or resurging infectious diseases in humans including dengue, chikungunya and Zika. Understanding the co-evolutionary processes among viruses and vectors is essential for the development of novel transmission-blocking strategies. Episomal viral DNA fragments are produced from arboviral RNA upon infection of mosquito cells and adults. Additionally, sequences from insect-specific viruses and arboviruses have been found integrated into mosquito genomes.

ResultsWe used a bioinformatic approach to analyse the presence, abundance, distribution, and transcriptional activity of integrations from 425 non-retroviral viruses, including 133 arboviruses, across the presently available 22 mosquito genome sequences. Large differences in abundance and types of viral integrations were observed in mosquito species from the same region. Viral integrations are unexpectedly abundant in the arboviral vector species Aedes aegypti and Ae. albopictus, in which they are approximately ~10-fold more abundant than in other mosquito species analysed. Additionally, viral integrations are enriched in piRNA clusters of both the Ae. aegypti and Ae. albopictus genomes and, accordingly, they express piRNAs, but not siRNAs.

ConclusionsDifferences in the number of viral integrations in the genomes of mosquito species from the same geographic area support the conclusion that integrations of viral sequences is not dependent on viral exposure, but that lineage-specific interactions exist. Viral integrations are abundant in Ae. aegypti and Ae. albopictus, and represent a thus far underappreciated component of their genomes. Additionally, the genome locations of viral integrations and their production of piRNAs indicate a functional link between viral integrations and the piRNA pathway. These results greatly expand the breadth and complexity of small RNA-mediated regulation and suggest a role for viral integrations in antiviral defense in these two mosquito species.

KeywordsMosquitoes Arboviruses Non-retroviral integrated RNA viruses Endogenous viral elements piRNA AbbreviationsBWABurrows-Wheeler Aligner

CHIKVchikungunya virus

Ctcycle threshold

DENVdengue viruses

EEEeastern equine encephalitis

EVEsEndogenous Viral Elements



ISVInsect Specific Virus

LRNA-dependent RNA polymerase

LACVLa Crosse virus

LTRlong terminal repeat LTR retrotransposons

MLMaximum likelihood


NIRVSNon-Retroviral Integrated RNA Viruses Sequences

ORFOpen Reading Frame

piRNAPIWI-interacting RNA

PTSpiRNA trigger sequence

RPKMReads per kilobase per million mapped reads

RVFVRift Valley fever virus

siRNAsmall interfering RNA

TEtransposable elements

VEEVenezuelan equine encephalitis

WNVWest Nile virus

ZKVZika virus

Electronic supplementary materialThe online version of this article doi:10.1186-s12864-017-3903-3 contains supplementary material, which is available to authorized users.

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Autor: Umberto Palatini - Pascal Miesen - Rebeca Carballar-Lejarazu - Lino Ometto - Ettore Rizzo - Zhijian Tu - Ronald P. van Ri


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