Evidence of direct cell–cell fusion in Borrelia by cryogenic electron tomography

Authors

  • Mikhail Kudryashev,

    1. Parasitology, Department of Infectious Diseases, University of Heidelberg Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
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    • Present address: Center for Cellular Imaging and Nano Analytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, CH-4058 Basel, Switzerland.

  • Marek Cyrklaff,

    1. Parasitology, Department of Infectious Diseases, University of Heidelberg Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
    2. Department of Molecular Structural Biology, Max Planck Institute for Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
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  • Björn Alex,

    1. Parasitology, Department of Infectious Diseases, University of Heidelberg Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
    2. Institute for Immunology, University of Heidelberg Medical School, Im Neuenheimer Feld 305, 69120 Heidelberg, Germany.
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  • Leandro Lemgruber,

    1. Parasitology, Department of Infectious Diseases, University of Heidelberg Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
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  • Wolfgang Baumeister,

    1. Department of Molecular Structural Biology, Max Planck Institute for Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
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  • Reinhard Wallich,

    Corresponding author
    1. Institute for Immunology, University of Heidelberg Medical School, Im Neuenheimer Feld 305, 69120 Heidelberg, Germany.
      E-mail reinhard.wallich@immu.uni-heidelberg.de; Tel. (+49) 6221 564090; Fax (+49) 6221 565611.
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  • Friedrich Frischknecht

    Corresponding author
    1. Parasitology, Department of Infectious Diseases, University of Heidelberg Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
      E-mail freddy.frischknecht@med.uni-heidelberg.de; Tel. (+49) 6221 566537; Fax (+49) 6221 566543;
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E-mail freddy.frischknecht@med.uni-heidelberg.de; Tel. (+49) 6221 566537; Fax (+49) 6221 566543;

E-mail reinhard.wallich@immu.uni-heidelberg.de; Tel. (+49) 6221 564090; Fax (+49) 6221 565611.

Summary

Some Borrelia species are the causative agents of tick-borne Lyme disease responsible for different disabilities depending on species and hosts. Borrelia are highly motile bacterial cells, and light microscopy shows that these spirochetes can associate with each other during movement. Using cryo-electron tomography, we observed closely associated Borrelia cells. Some of these showed a single outer membrane surrounding two longitudinally arranged cytoplasmic cylinders. We also observed fusion of two cytoplasmic cylinders and differences in the surface layer density of fused spirochetes. These processes could play a role in the interaction of Borrelia species with the host's immune system.

Ancillary