Analysis of Rickettsia typhi-infected and uninfected cat flea (Ctenocephalides felis) midgut cDNA libraries: deciphering molecular pathways involved in host response to R. typhi infection

Authors

  • S. M. Dreher-Lesnick,

    1. Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA;
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    • Sheila M. Dreher-Lesnick and Shane M. Ceraul contributed equally.

  • S. M. Ceraul,

    Corresponding author
    1. Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA;
      Shane M. Ceraul, Department of Microbiology and Immunology, University of Maryland School of Medicine, 685 W. Baltimore Street, Room HSFI Suite 380, Baltimore, MD 21201, USA. Tel.: +410 706 3337; fax: +410 706 0282; e-mail: scera001@umaryland.edu
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    • Sheila M. Dreher-Lesnick and Shane M. Ceraul contributed equally.

  • S. C. Lesnick,

    1. Department of Biology, Bioscience Research Building, University of Maryland College Park, College Park, MD, USA;
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  • J. J. Gillespie,

    1. Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA;
    2. Virginia Bioinformatics Institute, Bioinformatics Facility, Washington Street, Virginia Tech, Blacksburg, VA, USA; and
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  • J. M. Anderson,

    1. Vector Molecular Biology Unit, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institute of Health, Rockville, MD, USA
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  • R. C. Jochim,

    1. Vector Molecular Biology Unit, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institute of Health, Rockville, MD, USA
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  • J. G. Valenzuela,

    1. Vector Molecular Biology Unit, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institute of Health, Rockville, MD, USA
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  • A. F. Azad

    1. Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA;
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Shane M. Ceraul, Department of Microbiology and Immunology, University of Maryland School of Medicine, 685 W. Baltimore Street, Room HSFI Suite 380, Baltimore, MD 21201, USA. Tel.: +410 706 3337; fax: +410 706 0282; e-mail: scera001@umaryland.edu

Abstract

Murine typhus is a flea-borne febrile illness that is caused by the obligate intracellular bacterium, Rickettsia typhi. The cat flea, Ctenocephalides felis, acquires R. typhi by imbibing a bloodmeal from a rickettsemic vertebrate host. To explore which transcripts are expressed in the midgut in response to challenge with R. typhi, cDNA libraries of R. typhi-infected and uninfected midguts of C. felis were constructed. In this study, we examined midgut transcript levels for select C. felis serine proteases, GTPases and defence response genes, all thought to be involved in the fleas response to feeding or infection. An increase in gene expression was observed for the serine protease inhibitors and vesicular trafficking proteins in response to feeding. In addition, R. typhi infection resulted in an increase in gene expression for the chymotrypsin and rab5 that we studied. Interestingly, R. typhi infection had little effect on expression of any of the defence response genes that we studied. We are unsure as to the physiological significance of these gene expression profiles and are currently investigating their potential roles as it pertains to R. typhi infection. To our knowledge, this is the first report of differential expression of flea transcripts in response to infection with R. typhi.

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