{"title":"Discovery of a novel spotted fever group Rickettsia, “Candidatus Rickettsia kedanie,” in unfed larval chigger mites, Leptotrombidium scutellare","authors":"Motohiko Ogawa, Minenosuke Matsutani, Takashi Katayama, Nobuhiro Takada, Shinichi Noda, Mamoru Takahashi, Daisuke Kageyama, Nozomu Hanaoka, Hideki Ebihara","doi":"10.1111/1348-0421.13161","DOIUrl":null,"url":null,"abstract":"<p>Spotted fever group (SFG) rickettsia, the causative agent of SFG rickettsiosis, is predominantly carried by ticks, whereas <i>Orientia tsutusgamushi</i>, the causative agent of scrub typhus, is primarily transmitted by chigger mites in Japan. In this study, we attempted to isolate intracellular eubacteria from <i>Leptotrombidium scutellare</i>, a major vector of <i>O. tsutsugamushi</i>; moreover, we isolated an SFG rickettsia using a mosquito-derived cell line. Draft genome sequences of this unique isolate, by applying criteria for species delimitation, classified this isolate as a novel strain, proposed as “<i>Rickettsia kedanie</i>.” Further genetic analysis identified conserved virulence factors, and the isolate successfully propagated in mammalian cells, suggesting its ability to cause diseases in humans. The presence of SFG rickettsia in unfed larvae implies potential dual-pathogen carriage and reflects a symbiotic relationship similar to that between the mites and <i>O. tsutsugamushi</i>, indicating possibility of its transovarial transmission from female adults. Furthermore, conserved genomic similarity of the novel isolate to known SFG rickettsia suggests potential multiple hosts, including chiggers and ticks. In the natural environment, ticks, chigger mites, and wild animals may carry new isolates, complicating the infection cycle and increasing the transmission risks to humans. This discovery challenges the conventional association of SFG rickettsia with ticks, emphasizing its implications for research and disease control. However, this study was confined to a particular species of chigger mites and geographic area, underscoring the necessity for additional studies to comprehend the ecological dynamics, host interactions, and health implications linked to this newly identified SFG rickettsia.</p>","PeriodicalId":18679,"journal":{"name":"Microbiology and Immunology","volume":null,"pages":null},"PeriodicalIF":1.9000,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Microbiology and Immunology","FirstCategoryId":"3","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/1348-0421.13161","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"IMMUNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Spotted fever group (SFG) rickettsia, the causative agent of SFG rickettsiosis, is predominantly carried by ticks, whereas Orientia tsutusgamushi, the causative agent of scrub typhus, is primarily transmitted by chigger mites in Japan. In this study, we attempted to isolate intracellular eubacteria from Leptotrombidium scutellare, a major vector of O. tsutsugamushi; moreover, we isolated an SFG rickettsia using a mosquito-derived cell line. Draft genome sequences of this unique isolate, by applying criteria for species delimitation, classified this isolate as a novel strain, proposed as “Rickettsia kedanie.” Further genetic analysis identified conserved virulence factors, and the isolate successfully propagated in mammalian cells, suggesting its ability to cause diseases in humans. The presence of SFG rickettsia in unfed larvae implies potential dual-pathogen carriage and reflects a symbiotic relationship similar to that between the mites and O. tsutsugamushi, indicating possibility of its transovarial transmission from female adults. Furthermore, conserved genomic similarity of the novel isolate to known SFG rickettsia suggests potential multiple hosts, including chiggers and ticks. In the natural environment, ticks, chigger mites, and wild animals may carry new isolates, complicating the infection cycle and increasing the transmission risks to humans. This discovery challenges the conventional association of SFG rickettsia with ticks, emphasizing its implications for research and disease control. However, this study was confined to a particular species of chigger mites and geographic area, underscoring the necessity for additional studies to comprehend the ecological dynamics, host interactions, and health implications linked to this newly identified SFG rickettsia.
期刊介绍:
Microbiology and Immunology is published in association with Japanese Society for Bacteriology, Japanese Society for Virology, and Japanese Society for Host Defense Research. It is peer-reviewed publication that provides insight into the study of microbes and the host immune, biological and physiological responses.
Fields covered by Microbiology and Immunology include:Bacteriology|Virology|Immunology|pathogenic infections in human, animals and plants|pathogenicity and virulence factors such as microbial toxins and cell-surface components|factors involved in host defense, inflammation, development of vaccines|antimicrobial agents and drug resistance of microbes|genomics and proteomics.