The IS1111 insertion sequence used for detection of Coxiella burnetii is widespread in Coxiella-like endosymbionts of ticks.
Coxiella is a genus of obligate intracellular bacteria engaged in a variety of interactions with eukaryotes. The type species, Coxiella burnetii, infects several vertebrate species, including humans, and is the causative agent of Q fever. Multiple copies of a specific transposable element, the insertion sequence IS1111, are present in the genome of C. burnetii and are routinely used for confirmation of Q fever cases. Recently, many Coxiella-like bacteria that are closely related but genetically distinct to C. burnetii have been found in ticks. These Coxiella-like bacteria are maternally inherited endosymbionts, present at high prevalence in tick populations and engaged in mutualistic interactions with their arthropod hosts. In this study, the presence of IS1111 was examined in the Coxiella-like endosymbionts and in bacteria of the Coxiella sister-genus, Rickettsiella. This screening reveals that a wide range of IS1111 copies were present in the Coxiella-like endosymbionts of ticks. DNA sequencing further identified genetically divergent IS1111 copies, including degraded copies that constitute an important genomic fossil record of past IS1111 expansions. These results show that IS1111 is not specific to C. burnetii, suggesting that Q fever detection assays based only on this element may lead to misidentification with Coxiella-like endosymbionts.
Laboratoire MIVEGEC (Maladies Infectieuses et Vecteurs : Ecologie, Génétique, Evolution et Contrôle), Centre National de la Recherche Scientifique (UMR5290) - Université de Montpellier - Institut pour la Recherche et le Développement (UR224), F-34394 Montpellier, France olivier.duron@ird.fr.
Olivier
O
Duron
D000595:Amino Acid Sequence; D000818:Animals; D026862:Argasidae / Q000382:microbiology*; D003381:Coxiella / Q000235:genetics*; D016997:Coxiella burnetii / Q000235:genetics* / Q000302:isolation & purification*; D044125:Coxiellaceae / Q000235:genetics; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000302:isolation & purification; D016680:Genome, Bacterial; D006801:Humans; D026863:Ixodidae / Q000382:microbiology*; D011778:Q Fever / Q000175:diagnosis / Q000382:microbiology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013559:Symbiosis
D004251:DNA Transposable Elements; D004269:DNA, Bacterial
Coxiella burnetii; Coxiella-like endosymbionts; IS1111; Q fever; insertion sequence; ticks