Isolation, culture, and genome analysis of Rickettsia oklahomensis sp. nov. (Rickettsiales: Rickettsiaceae) from Amblyomma americanum (Acari: Ixodidae)

An uncharacterized Rickettsia species was previously identified by molecular detection in Amblyomma americanum ticks from Oklahoma, a state reported to have high Rickettsia seroprevalence. Amblyomma americanum ticks are aggressive feeders capable of transmitting viral, protozoal and bacterial specie...

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Main Authors: Michael Karounos, Praveen Kumar Korla, James Wilson, Sarah Clarke, Susan Little, Barbara Qurollo
Format: Article
Language:English
Published: Elsevier 2025-05-01
Series:Ticks and Tick-Borne Diseases
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Online Access:http://www.sciencedirect.com/science/article/pii/S1877959X25000469
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author Michael Karounos
Praveen Kumar Korla
James Wilson
Sarah Clarke
Susan Little
Barbara Qurollo
author_facet Michael Karounos
Praveen Kumar Korla
James Wilson
Sarah Clarke
Susan Little
Barbara Qurollo
author_sort Michael Karounos
collection DOAJ
description An uncharacterized Rickettsia species was previously identified by molecular detection in Amblyomma americanum ticks from Oklahoma, a state reported to have high Rickettsia seroprevalence. Amblyomma americanum ticks are aggressive feeders capable of transmitting viral, protozoal and bacterial species that cause diseases in humans and animals. Discovering and characterizing novel microorganisms in this tick species is crucial for identifying potential new pathogens. Using A. americanum ticks collected from Oklahoma, we isolated, cultured and sequenced the entire genome of a previously detected, but uncharacterized, novel Rickettsia species. Triturated A. americanum ticks were used as inoculum to culture the novel Rickettsia species in Vero E6 cells, and qPCR testing confirmed the presence of the new Rickettsia species while ruling out the presence of other tick-borne organisms. The total genome size was 1.17 Mbp consisting of a complete chromosome with a 30.7 % G+C content (GenBank accession CP157197). We predicted 1037 genes, 997 coding gene open reading frames, along with 33 tRNAs, 4 ncRNAs and 3 rRNAs. This genome was most similar to Rickettsia canadensis strain CA410 at 91.1 % identity, based on average nucleotide identity analysis. A maximum-likelihood phylogeny tree, constructed using 636 concatenated core proteins, placed the novel Rickettsia species in a clade with Rickettsia canadensis. We propose the name Rickettsia oklahomensis sp. nov., strain Oklahoma 10, which is available from the Centers for Disease Control and Prevention Rickettsial Isolate Reference Collection (WDCM 1093), Atlanta, GA, USA (CRIRC accession number ROK001).
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spelling doaj-art-6dffb7084e2a4ff3a6ad49e3d76c3d452025-08-20T03:19:56ZengElsevierTicks and Tick-Borne Diseases1877-96032025-05-0116310248210.1016/j.ttbdis.2025.102482Isolation, culture, and genome analysis of Rickettsia oklahomensis sp. nov. (Rickettsiales: Rickettsiaceae) from Amblyomma americanum (Acari: Ixodidae)Michael Karounos0Praveen Kumar Korla1James Wilson2Sarah Clarke3Susan Little4Barbara Qurollo5Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USADepartment of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USADepartment of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USADepartment of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USADepartment of Veterinary Pathobiology, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK, USADepartment of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA; Corresponding author.An uncharacterized Rickettsia species was previously identified by molecular detection in Amblyomma americanum ticks from Oklahoma, a state reported to have high Rickettsia seroprevalence. Amblyomma americanum ticks are aggressive feeders capable of transmitting viral, protozoal and bacterial species that cause diseases in humans and animals. Discovering and characterizing novel microorganisms in this tick species is crucial for identifying potential new pathogens. Using A. americanum ticks collected from Oklahoma, we isolated, cultured and sequenced the entire genome of a previously detected, but uncharacterized, novel Rickettsia species. Triturated A. americanum ticks were used as inoculum to culture the novel Rickettsia species in Vero E6 cells, and qPCR testing confirmed the presence of the new Rickettsia species while ruling out the presence of other tick-borne organisms. The total genome size was 1.17 Mbp consisting of a complete chromosome with a 30.7 % G+C content (GenBank accession CP157197). We predicted 1037 genes, 997 coding gene open reading frames, along with 33 tRNAs, 4 ncRNAs and 3 rRNAs. This genome was most similar to Rickettsia canadensis strain CA410 at 91.1 % identity, based on average nucleotide identity analysis. A maximum-likelihood phylogeny tree, constructed using 636 concatenated core proteins, placed the novel Rickettsia species in a clade with Rickettsia canadensis. We propose the name Rickettsia oklahomensis sp. nov., strain Oklahoma 10, which is available from the Centers for Disease Control and Prevention Rickettsial Isolate Reference Collection (WDCM 1093), Atlanta, GA, USA (CRIRC accession number ROK001).http://www.sciencedirect.com/science/article/pii/S1877959X25000469Rickettsia oklahomensisAmblyomma americanumGenomePhylogenyTickCulture
spellingShingle Michael Karounos
Praveen Kumar Korla
James Wilson
Sarah Clarke
Susan Little
Barbara Qurollo
Isolation, culture, and genome analysis of Rickettsia oklahomensis sp. nov. (Rickettsiales: Rickettsiaceae) from Amblyomma americanum (Acari: Ixodidae)
Ticks and Tick-Borne Diseases
Rickettsia oklahomensis
Amblyomma americanum
Genome
Phylogeny
Tick
Culture
title Isolation, culture, and genome analysis of Rickettsia oklahomensis sp. nov. (Rickettsiales: Rickettsiaceae) from Amblyomma americanum (Acari: Ixodidae)
title_full Isolation, culture, and genome analysis of Rickettsia oklahomensis sp. nov. (Rickettsiales: Rickettsiaceae) from Amblyomma americanum (Acari: Ixodidae)
title_fullStr Isolation, culture, and genome analysis of Rickettsia oklahomensis sp. nov. (Rickettsiales: Rickettsiaceae) from Amblyomma americanum (Acari: Ixodidae)
title_full_unstemmed Isolation, culture, and genome analysis of Rickettsia oklahomensis sp. nov. (Rickettsiales: Rickettsiaceae) from Amblyomma americanum (Acari: Ixodidae)
title_short Isolation, culture, and genome analysis of Rickettsia oklahomensis sp. nov. (Rickettsiales: Rickettsiaceae) from Amblyomma americanum (Acari: Ixodidae)
title_sort isolation culture and genome analysis of rickettsia oklahomensis sp nov rickettsiales rickettsiaceae from amblyomma americanum acari ixodidae
topic Rickettsia oklahomensis
Amblyomma americanum
Genome
Phylogeny
Tick
Culture
url http://www.sciencedirect.com/science/article/pii/S1877959X25000469
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