Genetic characterization and transovarial transmission of a typhus-like rickettsia found in cat fleas.

Azad, Abdu F.; Sacci, John B.; Nelson, William M.; Dasch, Gregory A.; Schmidtmann, E. T.; Carl, Mitchell

doi:10.1073/pnas.89.1.43

Cited by 142 publications

(132 citation statements)

References 19 publications

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“…The fact that R. belfii represents a phylogenetic line that predates the TG-SFG split suggests that the use of insects as primary hosts was a secondary event within the TG and that the genus Rickettsia is primarily associated with ticks. This is consistent with the more severe deleterious effects of TG organisms (with the possible exception of the recently described ELB agent [3]) on their insect arthropod hosts than of SFG organisms on their acarine hosts (35). Examination of the molecular placement of R. Canada, a putative TG member which is associated with ticks, should provide further evidence about the movement of the TG into insects.…”

Section: Discussionsupporting

confidence: 71%

Ancestral Divergence of Rickettsia bellii from the Spotted Fever and Typhus Groups of Rickettsia and Antiquity of the Genus Rickettsia

Stothard

Clark

Fuerst

1994

International Journal of Systematic Bacteriology

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The eubacterial genus Rickettsia belongs to the cu subgroup of the phylum Proteobacteriu. This genus is usually divided into three biotypes on the basis of vector host and antigenic cross-reactivity characteristics. However, the species Rickettsia bellii does not fit into this classification scheme; this organism has characteristics common to both the spotted fever group and the typhus group biotypes and also exhibits some unique features. Sequences of the 16s rRNA and 23s rRNA genes from Rickettsia rickettsii (spotted fever group), Rickettsia prowazekii (typhus group), and R. bellii were studied to determine the position of R. bellii in the rickettsia1 classification scheme. The 23s rRNA gene sequences described in this paper are the first 23s rRNA sequences reported for any member of the Rickettsiuceue. The 23s rRNA gene contains substantially more phylogenetic information than is contained in the 16s rRNA sequences, and the 23s rRNA gene sequence has diverged about 1.9 times faster in the three Rickettsia species which we studied. Taken together, the molecular data obtained from the two genes indicate that R. bellii is not a member of either the spotted fever group or the typhus group; rather, this organism appears to be the product of a divergence which predates the separation of the genus into the spotted fever group and the typhus group. Consequently, different combinations of the ancestral characteristics retained by R. bellii have been retained in the more derived lineages of the genus. A comparison of the 16s rRNA and 23s rRNA gene sequences of Rickettsia strains with other proteobacterial sequences confirmed that the genus Rickettsia is a unique deeply branching member of the cu subgroup of the Proteobacteria and that the Rickettsia species form a monophyletic cluster. While divergence of the contemporary members of the genus Rickettsia occurred recently, the unique evolutionary line represented by this genus appears to be very old.Rickettsia strains are small, gram-negative bacteria that are intimately associated with eukaryotic cells and are members of a diverse family, the Rickettsiaceae, which also includes other intracellular organisms, including the genera Ehrlichia, Wolbachia, Anaplasma, and Cowdria (4,36). Rickettsiae have natural arthropod hosts (either ticks, mites, or insects) and can be pathogenic for humans and other vertebrates. The obligately intracellular lifestyle and fastidious nature of these organisms have made them difficult to study. A number of genotypic and phenotypic characteristics indicate that the Rickettsia species are closely related, and this genus is now recognized as the sole member of a branch of the cx subgroup Proteobacteriu (8) on the basis of 16s rRNA cataloging and partial 16s rRNA gene sequence data (34).The genus Rickettsia is divided into three biotypes on the basis of immunological cross-reactivity and ecological characteristics (36). Rickettsia species are placed into the spotted fever group (SFG), the typhus group (TG), or the scrub typhus group on the basis...

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Section: Discussionsupporting

confidence: 71%

Ancestral Divergence of Rickettsia bellii from the Spotted Fever and Typhus Groups of Rickettsia and Antiquity of the Genus Rickettsia

Stothard

Clark

Fuerst

1994

International Journal of Systematic Bacteriology

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“…felis has traditionally been placed within the TG of Rickettsia on the basis of reactivity of R. felis antigens with antibodies to R. typhi and the previous association of the TG with insects and the SFG with acarines (Adams et al, 1990 ;Azad et al, 1992). In contrast, data from genetic studies would place R. felis in the SFG Roux & Raoult, 1995 ;Stothard & Fuerst, 1995).…”

Section: Electron Microscopymentioning

confidence: 76%

“…Although the existence of the R. felis rOmpA is of importance, we are left to ponder the reactivity of R. felis with antibodies stimulated by R. typhi . It could be debated that the first identification of R. felis in the cat flea was in fact R. typhi, but this seems unlikely as shown by the distinct RFLP pattern of the R. felis CS and 17 kDa protein genes and their DNA sequences (Higgins et al, 1996 ;Azad et al, 1992). Perhaps a more plausible theory is that R. felis is closer to the common Rickettsia ancestor on the evolutionary scale than any of the previously analysed species.…”

Section: International Journal Of Systematic and Evolutionary Microbimentioning

confidence: 99%

Rickettsia felis: molecular characterization of a new member of the spotted fever group.

Bouyer¹,

Stenos²,

Crocquet‐Valdes³

et al. 2001

International Journal of Systematic and Evolutionary Microbiology

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126

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In this report, placement of Rickettsia felis in the spotted fever group (SFG) rather than the typhus group (TG) of Rickettsia is proposed. The organism, which was first observed in cat fleas (Ctenocephalides felis) by electron microscopy, has not yet been reported to have been cultivated reproducibly, thereby limiting the standard rickettsial typing by serological means. To overcome this challenge, several genes were selected as targets to be utilized for the classification of R. felis. DNA from cat fleas naturally infected with R. felis was amplified by PCR utilizing primer sets specific for the 190 kDa surface antigen (rOmpA) and 17 kDa antigen genes. The entire 5513 bp rompA gene was sequenced, characterized and found to have several unique features when compared to the rompA genes of other Rickettsia. Phylogenetic analysis of the partial sequence of the 17 kDa antigen gene indicated that R. felis is less divergent from the SFG rickettsiae than from the TG rickettsiae. The data corroborate results from previous reports that analysed the citrate synthase, 16S rRNA, rompB (135 kDa surface antigen), metK, ftsY, polA and dnaE genes that placed R. felis as a member of the SFG. The organism is passed transstadially and transovarially, and infection in the cat flea has been observed in the midgut, tracheal matrix, muscle, hypodermis, ovaries and testes.

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“…Moreover, by using PCR the limitations of traditional culturedependent technique, which requires the isolation and culture of bacteria, is overcome (Ranjard et al, 2000). The widespread use of PCR/RFLP for the characterization of Rickettsia (Regnery et al, 1991;Gage et al, 1994;Roux et al, 1996) including R. felis (Azad et al, 1992;Schriefer et al, 1994;Boostrom et al, 2002) has facilitated rickettsial identification in the absence of culture. The use of colonized C. felis greatly advances research efforts toward the delineation of flea biology, control and pathogen interaction (Thomas et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

Comparative microbiota of Rickettsia felis-uninfected and -infected colonized cat fleas, Ctenocephalides felis

et al. 2007

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Fleas serve as arthropod vectors for several emerging and re-emerging infectious disease causing agents including, Rickettsia felis. Although the prevalence of R. felis infection in colonies of fleas has been examined, the influence of the R. felis infection on flea microbiota has not been investigated. We identified three colonies of cat fleas, Ctenocephalides felis, with varying prevalence of R. felis infection (Louisiana State University (LSU), 93.8%; Professional Laboratory and Research Services Inc. (PLRS), 16.4%; Elward II (EL), 0%) and subsequently utilized polymerase chain reaction amplification, restriction fragment length polymorphism analysis and sequencing of the 1.4-kb portions of 16S rRNA genes to examine the diversity of bacteria in the flea populations. A total of 17 different bacterial 16S rRNA gene sequences were identified among the C. felis colonies. The prevalence of two Wolbachia species that were identified in each flea colony differed between colonies and R. felis-uninfected and -infected fleas. Species richness was unchanged among the R. felis-uninfected (LSU, PLRS and EL colonies) and -infected (LSU and PLRS colonies) fleas; however, between R. felis-uninfected and -infected fleas within both the LSU and PLRS colonies, R. felisuninfected fleas have greater species richness. Diversity indices did not identify a difference in diversity between any of the flea samples. The interaction of endosymbionts within arthropods can widely impact the dissemination of vertically transmitted pathogenic bacteria; and the reciprocal may be true. These results suggest that carriage of R. felis has an impact on the richness of flea microbiota.

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Genetic characterization and transovarial transmission of a typhus-like rickettsia found in cat fleas.

Cited by 142 publications

References 19 publications

Ancestral Divergence of Rickettsia bellii from the Spotted Fever and Typhus Groups of Rickettsia and Antiquity of the Genus Rickettsia

Ancestral Divergence of Rickettsia bellii from the Spotted Fever and Typhus Groups of Rickettsia and Antiquity of the Genus Rickettsia

Rickettsia felis: molecular characterization of a new member of the spotted fever group.

Comparative microbiota of Rickettsia felis-uninfected and -infected colonized cat fleas, Ctenocephalides felis

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