Letter

Insect symbiotic bacteria harbour viral pathogens for transovarial transmission

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Published online:

Abstract

Many insects, including mosquitoes, planthoppers, aphids and leafhoppers, are the hosts of bacterial symbionts and the vectors for transmitting viral pathogens1,​2,​3. In general, symbiotic bacteria can indirectly affect viral transmission by enhancing immunity and resistance to viruses in insects3,​4,​5. Whether symbiotic bacteria can directly interact with the virus and mediate its transmission has been unknown. Here, we show that an insect symbiotic bacterium directly harbours a viral pathogen and mediates its transovarial transmission to offspring. We observe rice dwarf virus (a plant reovirus) binding to the envelopes of the bacterium Sulcia, a common obligate symbiont of leafhoppers6,​7,​8, allowing the virus to exploit the ancient oocyte entry path of Sulcia in rice leafhopper vectors. Such virus–bacterium binding is mediated by the specific interaction of the viral capsid protein and the Sulcia outer membrane protein. Treatment with antibiotics or antibodies against Sulcia outer membrane protein interferes with this interaction and strongly prevents viral transmission to insect offspring. This newly discovered virus–bacterium interaction represents the first evidence that a viral pathogen can directly exploit a symbiotic bacterium for its transmission. We believe that such a model of virus–bacterium communication is a common phenomenon in nature.

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Author information

Author notes

    • Dongsheng Jia
    • , Qianzhuo Mao
    •  & Yong Chen

    These authors contributed equally to this work.

Affiliations

  1. State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, People's Republic of China

    • Dongsheng Jia
    • , Qianzhuo Mao
    • , Yong Chen
    • , Yuyan Liu
    • , Qian Chen
    • , Wei Wu
    • , Xiaofeng Zhang
    • , Hongyan Chen
    •  & Taiyun Wei
  2. State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China

    • Yi Li

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Contributions

All authors read and approved the manuscript. D.J., Q.M., Y.C., Y.Li and T.W. conceived and designed the study, and wrote the paper. D.J., Q.M. and Y.C. contributed equally to this work, performed most experiments and helped with data analysis. Y.Liu and H.C. performed the transmission electron microscopy. W.W. and X.Z. performed gene cloning and immunoprecipitation. Q.C. performed RT–qPCR experiments. Y.Li and T.W. discussed the data and revised the manuscript. T.W. and Y.Li organized and directed the project.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Yi Li or Taiyun Wei.

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