Defending the fort: a role for defensin-2 in limiting Rickettsia montanensis infection of Dermacentor variabilis

Authors

  • R. S. Pelc,

    1. Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
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    • Authors contributed equally.
  • J. C. McClure,

    1. Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
    2. Irish Cattle Breeders Federation Society Ltd, Bandon, Co Cork, UK
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    • Authors contributed equally.
  • K. T. Sears,

    1. Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
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  • A. Chung,

    1. Food and Drug Administration, Bethesda, MD, USA
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  • M. S. Rahman,

    1. Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
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  • S. M. Ceraul

    Corresponding author
    1. Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
    • Correspondence: Shane M. Ceraul, Department of Microbiology and Immunology, University of Maryland School of Medicine, HSFI Suite 380, 685 West Baltimore Street, Baltimore, MD 21201, USA. Tel.: +410 706-3750; e-mail: scera001@umaryland.edu

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Abstract

The importance of tick defensins is evidenced by their expression in a wide variety of tick tissues and prevalence across many tick genera. To date, the functional and biological significance of defensin-2 as a rickettsiastatic or rickettsiacidal antimicrobial peptide has not been addressed. In a previous study, defensin-2 transcription was shown to increase in Dermacentor variabilis ticks challenged with Rickettsia montanensis. In the present study, the hypothesis that defensin-2 is functional as a rickettsiastatic and/or rickettsiacidal antimicrobial peptide is tested. We show that defensin-2 plays a role in reducing burden after acquisition of Rickettsia montanensis through capillary feeding. Moreover, defensin-2 is shown to associate with R. montanensis in vitro and in vivo, causing cytoplasmic leakiness.

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