Animal virus replication and RNAi-mediated antiviral silencing in Caenorhabditis elegans

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The worm Caenorhabditis elegans is a model system for studying many aspects of biology, including host responses to bacterial pathogens1,2, but it is not known to support replication of any virus. Plants and insects encode multiple Dicer enzymes that recognize distinct precursors of small RNAs and may act cooperatively3,4,5,6,7. However, it is not known whether the single Dicer of worms and mammals is able to initiate the small RNA-guided RNA interference (RNAi) antiviral immunity as occurs in plants8 and insects9. Here we show complete replication of the Flock house virus (FHV) bipartite, plus-strand RNA genome in C. elegans. We show that FHV replication in C. elegans triggers potent antiviral silencing that requires RDE-1, an Argonaute protein10,11 essential for RNAi mediated by small interfering RNAs (siRNAs) but not by microRNAs. This immunity system is capable of rapid virus clearance in the absence of FHV B2 protein, which acts as a broad-spectrum RNAi inhibitor9,12 upstream of rde-1 by targeting the siRNA precursor. This work establishes a C. elegans model for genetic studies of animal virus–host interactions and indicates that mammals might use a siRNA pathway as an antiviral response.

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Figure 1: Replication and silencing of FHV in C. elegans.
Figure 2: FHV RNAi suppressor is active in rde-1 worms.
Figure 3: FHV B2 is a dsRNA-binding protein and inhibits siRNA production in vitro.


  1. 1

    Brenner, S. The genetics of Caenorhabditis elegans. Genetics 77, 71–94 (1974)

  2. 2

    Mahajan-Miklos, S., Tan, M. W., Rahme, L. G. & Ausubel, F. M. Molecular mechanisms of bacterial virulence elucidated using a Pseudomonas aeruginosaCaenorhabditis elegans pathogenesis model. Cell 96, 47–56 (1999)

  3. 3

    Fire, A. et al. Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. Nature 391, 806–811 (1998)

  4. 4

    Xie, Z. et al. Genetic and functional diversification of small RNA pathways in plants. PLoS Biol. 2, 642–652 (2004)

  5. 5

    Lee, Y. S. et al. Distinct roles for Drosophila Dicer-1 and Dicer-2 in the siRNA/miRNA silencing pathways. Cell 117, 69–81 (2004)

  6. 6

    Tomari, Y. & Zamore, P. D. Perspective: machines for RNAi. Genes Dev. 19, 517–529 (2005)

  7. 7

    Bernstein, E., Caudy, A. A., Hammond, S. M. & Hannon, G. J. Role for a bidentate ribonuclease in the initiation step of RNA interference. Nature 409, 363–366 (2001)

  8. 8

    Hamilton, A. J. & Baulcombe, D. C. A species of small antisense RNA in posttranscriptional gene silencing in plants. Science 286, 950–952 (1999)

  9. 9

    Li, H. W., Li, W. X. & Ding, S. W. Induction and suppression of RNA silencing by an animal virus. Science 296, 1319–1321 (2002)

  10. 10

    Tabara, H. et al. The rde-1 gene, RNA interference, and transposon silencing in C. elegans. Cell 99, 123–132 (1999)

  11. 11

    Hammond, S. M., Boettcher, S., Caudy, A. A., Kobayashi, R. & Hannon, G. J. Argonaute2, a link between genetic and biochemical analyses of RNAi. Science 293, 1146–1150 (2001)

  12. 12

    Li, W. X. et al. Interferon antagonist proteins of influenza and vaccinia viruses are suppressors of RNA silencing. Proc. Natl Acad. Sci. USA 101, 1350–1355 (2004)

  13. 13

    Ball, L. A. & Johnson, K. L. Reverse genetics of nodaviruses. Adv. Virus Res. 53, 229–244 (1999)

  14. 14

    Grishok, A., Sinskey, J. L. & Sharp, P. A. Transcriptional silencing of a transgene by RNAi in the soma of C. elegans. Genes Dev. 19, 683–696 (2005)

  15. 15

    Vastenhouw, N. L. & Plasterk, R. H. RNAi protects the Caenorhabditis elegans germline against transposition. Trends Genet. 20, 314–319 (2004)

  16. 16

    Silhavy, D. & Burgyan, J. Effects and side-effects of viral RNA silencing suppressors on short RNAs. Trends Plant Sci. 9, 76–83 (2004)

  17. 17

    Li, W. X. & Ding, S. W. Viral suppressors of RNA silencing. Curr. Opin. Biotechnol. 12, 150–154 (2001)

  18. 18

    Voinnet, O. Induction and suppression of RNA silencing: insights from viral infections. Nature Rev. Genet. 6, 206–220 (2005)

  19. 19

    Ding, S. W., Li, H., Lu, R., Li, F. & Li, W. X. RNA silencing: a conserved antiviral immunity of plants and animals. Virus Res. 102, 109–115 (2004)

  20. 20

    Okamura, K., Ishizuka, A., Siomi, H. & Siomi, M. C. Distinct roles for Argonaute proteins in small RNA-directed RNA cleavage pathways. Genes Dev. 18, 1655–1666 (2004)

  21. 21

    Pfeffer, S. et al. Identification of virus-encoded microRNAs. Science 304, 734–736 (2004)

  22. 22

    Lecellier, C. H. et al. A cellular microRNA directs antiviral immunity in human cells. Science 308, 557–560 (2005)

  23. 23

    Lee, W. M. & Ahlquist, P. Membrane synthesis, specific lipid requirements, and localized lipid composition changes associated with a positive-strand RNA virus RNA replication protein. J. Virol. 77, 12819–12828 (2003)

  24. 24

    Stringham, E. G., Dixon, D. K., Jones, D. & Candido, E. P. Temporal and spatial expression patterns of the small heat shock (hsp16) genes in transgenic Caenorhabditis elegans. Mol. Biol. Cell 3, 221–233 (1992)

  25. 25

    Mello, C. C., Kramer, J. M., Stinchcomb, D. & Ambros, V. Efficient gene transfer in C. elegans: extrachromosomal maintenance and integration of transforming sequences. EMBO J. 10, 3959–3970 (1991)

  26. 26

    Maduro, M. F., Meneghini, M. D., Bowerman, B., Broitman-Maduro, G. & Rothman, J. H. Restriction of mesendoderm to a single blastomere by the combined action of SKN-1 and a GSK-3β homolog is mediated by MED-1 and -2 in C. elegans. Mol. Cell 7, 475–485 (2001)

  27. 27

    Timmons, L., Court, D. L. & Fire, A. Ingestion of bacterially expressed dsRNAs can produce specific and potent genetic interference in Caenorhabditis elegans. Gene 263, 103–112 (2001)

  28. 28

    Silhavy, D. et al. A viral protein suppresses RNA silencing and binds silencing-generated, 21- to 25-nucleotide double-stranded RNAs. EMBO J. 21, 3070–3080 (2002)

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We thank X. Huang for recommending the use of pPD49.83, and the Caenorhabditis Genetics Center funded by the National Center for Research Resources of the National Institutes of Health for some of the strains used in this work. This project was supported by an NIH grant and USDA National Research Initiative Competitive Grants Program awards (to S.W.D.) and UC Riverside startup funds (to M.M).

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Correspondence to S. W. Ding.

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