Wolbachia Blocks Viral Genome Replication Early in Infection without a Transcriptional Response by the Endosymbiont or Host Small RNA Pathways

PLoS Pathogens

Punita Juneja¹  Francis M. Jiggins¹  Julien Martinez¹  Eric A. Miska²  Aleksei Lulla³  Andres Merits³  Peter Sarkies⁴  Esther Schnettler⁵  Melanie McFarlane⁵  Stephanie M. Rainey⁵  Margus Varjak⁵  Alain Kohl⁵ 

[1] Department of Genetics, University of Cambridge, Cambridge, United Kingdom;Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom;Institute of Technology, University of Tartu, Tartu, Estonia;MRC Clinical Sciences Centre, Imperial College London, London, United Kingdom;MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom

关键词: Wolbachia;    Viral replication;    Small interfering RNAs;    Drosophila melanogaster;    MicroRNAs;    Invertebrate genomics;    Protein translation;    Arboviral infections;   

DOI  :  10.1371/journal.ppat.1005536

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The intracellular endosymbiotic bacterium Wolbachia can protect insects against viral infection, and is being introduced into mosquito populations in the wild to block the transmission of arboviruses that infect humans and are a major public health concern. To investigate the mechanisms underlying this antiviral protection, we have developed a new model system combining Wolbachia-infected Drosophila melanogaster cell culture with the model mosquito-borne Semliki Forest virus (SFV; Togaviridae, Alphavirus). Wolbachia provides strong antiviral protection rapidly after infection, suggesting that an early stage post-infection is being blocked. Wolbachia does appear to have major effects on events distinct from entry, assembly or exit as it inhibits the replication of an SFV replicon transfected into the cells. Furthermore, it causes a far greater reduction in the expression of proteins from the 3´ open reading frame than the 5´ non-structural protein open reading frame, indicating that it is blocking the replication of viral RNA. Further to this separation of the replicase proteins and viral RNA in transreplication assays shows that uncoupling of viral RNA and replicase proteins does not overcome Wolbachia’s antiviral activity. This further suggests that replicative processes are disrupted, such as translation or replication, by Wolbachia infection. This may occur by Wolbachia mounting an active antiviral response, but the virus did not cause any transcriptional response by the bacterium, suggesting that this is not the case. Host microRNAs (miRNAs) have been implicated in protection, but again we found that host cell miRNA expression was unaffected by the bacterium and neither do our findings suggest any involvement of the antiviral siRNA pathway. We conclude that Wolbachia may directly interfere with early events in virus replication such as translation of incoming viral RNA or RNA transcription, and this likely involves an intrinsic (as opposed to an induced) mechanism.

【 授权许可】

CC BY