Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Architecture of ribonucleoprotein complexes in influenza A virus particles

Abstract

In viruses, as in eukaryotes, elaborate mechanisms have evolved to protect the genome and to ensure its timely replication and reliable transmission to progeny. Influenza A viruses are enveloped, spherical or filamentous structures, ranging from 80 to 120 nm in diameter1. Inside each envelope is a viral genome consisting of eight single-stranded negative-sense RNA segments of 890 to 2,341 nucleotides each1. These segments are associated with nucleoprotein and three polymerase subunits, designated PA, PB1 and PB2; the resultant ribonucleoprotein complexes (RNPs) resemble a twisted rod (10–15 nm in width and 30–120 nm in length) that is folded back and coiled on itself2,3,4. Late in viral infection, newly synthesized RNPs are transported from the nucleus to the plasma membrane, where they are incorporated into progeny virions capable of infecting other cells. Here we show, by transmission electron microscopy of serially sectioned virions, that the RNPs of influenza A virus are organized in a distinct pattern (seven segments of different lengths surrounding a central segment). The individual RNPs are suspended from the interior of the viral envelope at the distal end of the budding virion and are oriented perpendicular to the budding tip. This finding argues against random incorporation of RNPs into virions5, supporting instead a model in which each segment contains specific incorporation signals that enable the RNPs to be recruited and packaged as a complete set6,7,8,9,10,11,12. A selective mechanism of RNP incorporation into virions and the unique organization of the eight RNP segments may be crucial to maintaining the integrity of the viral genome during repeated cycles of replication.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Budding virions show a specific arrangement of eight rod-like structures of different lengths.
Figure 2: Rod-like structures in a developing virion.
Figure 3: Identification of rod-like structures in virions as viral RNPs.
Figure 4: Electron tomography of RNP complexes in a budding virion.

Similar content being viewed by others

References

  1. Lamb, R. A. & Krug, R. M. in Fields Virology (eds Knipe, D. M. & Howley, P. M.) 1487–1532 (Lippincott, Williams & Wilkins, Philadelphia, 2001)

    Google Scholar 

  2. Compans, R. W., Content, J. & Duesberg, P. H. Structure of ribonucleoprotein of influenza virus. J. Virol. 10, 795–800 (1972)

    CAS  PubMed  PubMed Central  Google Scholar 

  3. Heggeness, M. H. et al. Studies on the helical nucleocapsid of influenza virus. Virology 118, 466–470 (1982)

    Article  CAS  Google Scholar 

  4. Oxford, J. S. & Hockley, D. J. Orthomyxoviridae. Animal Virus Structure 213–232 (Elsevier, Amsterdam, 1987)

    Book  Google Scholar 

  5. Enami, M., Sharma, G., Benham, C. & Palese, P. An influenza virus containing nine different RNA segments. Virology 185, 291–298 (1991)

    Article  CAS  Google Scholar 

  6. Duhaut, S. D. & McCauley, J. W. Defective RNAs inhibit the assembly of influenza virus genome segments in a segment-specific manner. Virology 216, 326–337 (1996)

    Article  CAS  Google Scholar 

  7. Odagiri, T. & Tashiro, M. Segment-specific noncoding sequences of the influenza virus genome RNA are involved in the specific competition between defective interfering RNA and its progenitor RNA segment at the virion assembly step. J. Virol. 71, 2138–2145 (1997)

    CAS  PubMed  PubMed Central  Google Scholar 

  8. Fujii, Y. et al. Selective incorporation of influenza virus RNA segment into virions. Proc. Natl Acad. Sci. USA 100, 2002–2007 (2003)

    Article  ADS  CAS  Google Scholar 

  9. Watanabe, T. et al. Exploitation of nucleic acid packaging signals to generate a novel influenza virus-based vector stably expressing two foreign genes. J. Virol. 77, 10575–10583 (2003)

    Article  CAS  Google Scholar 

  10. Fujii, K. et al. Importance of both the coding and the segment-specific noncoding regions of the influenza A virus NS segment for its efficient incorporation into virions. J. Virol. 79, 3766–3774 (2005)

    Article  CAS  Google Scholar 

  11. Liang, Y., Hong, Y. & Parslow, T. G. cis-Acting packaging signals in the influenza virus PB1, PB2, and PA genomic RNA segments. J. Virol. 79, 10348–10355 (2005)

    Article  CAS  Google Scholar 

  12. Dos Santos Afonso, E. et al. The generation of recombinant influenza A viruses expressing a PB2 fusion protein requires the conservation of a packaging signal overlapping the coding and noncoding regions at the 5′ end of the PB2 segment. Virology 341, 34–46 (2005)

    Article  Google Scholar 

  13. Schulze, I. T. The structure of influenza virus. Virology 42, 890–904 (1970)

    Article  CAS  Google Scholar 

  14. Medalia, O. et al. Macromolecular architecture in eukaryotic cells visualized by cryoelectron tomography. Science 298, 1209–1213 (2002)

    Article  ADS  CAS  Google Scholar 

  15. Noda, T. et al. Ebola virus VP40 drives the formation of virus-like filamentous particles along with GP. J. Virol. 76, 4855–4865 (2002)

    Article  CAS  Google Scholar 

  16. Bendayan, M. & Zollinger, M. Ultrastructural localization of antigenic sites on osmium-fixed tissues applying the protein A–gold technique. J. Histochem. Cytochem. 31, 101–109 (1983)

    Article  CAS  Google Scholar 

  17. Bendayan, M. & Maestracci, N. D. Pituitary adenomas: patterns of hPRL and hGH secretion as revealed by high resolution immunocytochemistry. Biol. Cell 52, 129–138 (1984)

    Article  CAS  Google Scholar 

  18. Kremer, J. R., Mastronarde, D. N. & McIntosh, J. R. Computer visualization of three-dimensional image data using IMOD. J. Struct. Biol. 116, 71–76 (1996)

    Article  CAS  Google Scholar 

Download references

Acknowledgements

We thank J. Gilbert for editing the manuscript; M. Imai, Y. Muramoto and K. Fujii for discussion; Y. Hirata, K. Aoyama and K. Inoke for technical assistance with electron microscopic tomography; and Y. Kawaoka for illustrations. This work was supported by CREST (Japan Science and Technology Agency), by Grants-in-Aid by the Ministry of Education, Culture, Sports, Science and Technology, by the Ministry of Health, Labor and Welfare, Japan, and by a National Institute of Allergy and Infectious Disease Public Health Service research grant (to Y.K.); and by Swedish Research Council grants and the STINT Foundation (to R.H.C.). T.N. was the recipient of a fellowship from the incorporated foundation SYOUSHISYA and a research fellowship from the Japan Society for the Promotion of Science for Young Scientists.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Yoshihiro Kawaoka.

Ethics declarations

Competing interests

Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Supplementary information

Supplementary Figures

This file contains Supplementary Figures 1–4. (PDF 1946 kb)

Supplementary Figure Legends Figures

This file contains text to accompany the above Supplementary Figures. (DOC 20 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Noda, T., Sagara, H., Yen, A. et al. Architecture of ribonucleoprotein complexes in influenza A virus particles. Nature 439, 490–492 (2006). https://doi.org/10.1038/nature04378

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature04378

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing