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

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.

Identification of genes associated with blood feeding in the cat flea, Ctenocephalides felis

“…Most of these sequences had a predicted signal peptide for extracellular secretion. These findings were broadly consistent with other transcriptomic studies demonstrating differential gene expression in response to blood feeding in fleas and other hematophagous ectoparasites [ 5 , 6 , 11 , 14 – 16 ].…”

“…3 . The remainder appeared to be molecules with various protective roles, namely a serine protease inhibitor (serpin; S49) with high similarity (96 %) to a previously described C. felis serpin [ 6 ], a novel peptidoglycan recognition protein (PGRP; B52) with 61 % homology to a C. felis PGRP LB-like protein [ 11 ], and two related novel mucins (S58 and B68), both with 36 % homology to a predicted Japanese medaka mucin-17-like protein [ 12 ]. The remaining two annotated gene products lacked predicted signal peptides and therefore likely represent intracellular proteins.…”

Gene Expression Analysis of Xenopsylla cheopis (Siphonaptera: Pulicidae) Suggests a Role for Reactive Oxygen Species in Response to Yersinia pestis Infection

“…The data were analyzed by analysis of variance (ANOVA) followed by TukeyÕs Multiple Comparison Test using GraphPad Prism, *P Ͻ 0.05, **P Ͻ 0.005, ***P Ͻ 0.001. tween diverse insects that span the orders Diptera, Hymenoptera, Lepidoptera, and Coleoptera, but there are also important differences between individual species and groups. Until recently (Andersen et al 2007, Dreher-Lesnick et al 2010, there has been a paucity of genome, transcriptome, and proteome data available for molecular studies of transmission of infectious microbes by Siphonaptera, despite their medical and veterinary importance.…”

PATRIC: the Comprehensive Bacterial Bioinformatics Resource with a Focus on Human Pathogenic Species

“…Our efforts have also been utilized in various collaborations generating experimental research (15,45). As such, with the recurrent expansion of the scope of information integration, PATRIC's infrastructure will continue to grow through developments driven by various collaborations with the infectiousdisease research community, education and outreach activities, community engagement and feedback, and continuing PATRIC-driven research.…”