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Home / Equine Research Bank / J Clin Microbiol / Real-Time PCR Differential Detection of Neorickettsia findla...
Journal of clinical microbiology2022; 60(7); e0025022; doi: 10.1128/jcm.00250-22

Real-Time PCR Differential Detection of Neorickettsia findlayensis and N. risticii in Cases of Potomac Horse Fever.

Abstract: Potomac horse fever (PHF) is an acute and potentially fatal enterotyphlocolitis of horses with clinical signs that include anorexia, fever, diarrhea, and laminitis. Its incidence is increasing despite a commercially available vaccine. PHF is caused by Neorickettsia risticii, and the recently rediscovered and classified . PHF diagnosis is currently accomplished using serology or nested PCR. However, both methods cannot distinguish the two species that cause PHF. Further, the current real-time PCR test fails to detect Thus, in this study, two species-specific real-time PCR assays based on and a genus-specific real-time PCR assay based on 16S rRNA gene were developed. The real-time PCR tests differentiated from in the field samples for which infection with either species had been verified using multiple other molecular tests and culture isolation, and the 16S rRNA gene real-time PCR detected both species in the samples. These tests were applied to new field culture isolates from three Canadian provinces (Alberta, Quebec, Ontario) and Ohio as well as archival DNA samples from suspected PHF cases to estimate the prevalence of in different geographic regions. The results suggest that frequently causes PHF in horses in Alberta and Quebec. The development of these tests will allow rapid, sensitive, and specific diagnosis of horses presenting with clinical signs of PHF. These tests will also enable rapid and targeted treatment and help develop broad-spectrum vaccines for PHF.
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Publication Date: 2022-06-13 PubMed ID: 35695520PubMed Central: PMC9297838DOI: 10.1128/jcm.00250-22Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The study creates new, species-specific, real-time PCR tests for accurately diagnosing Potomac Horse Fever (PHF) caused by Neorickettsia species, previously indistinguishable.

Background and Objective

  • Potomac Horse Fever (PHF) is a severe and potentially lethal condition in horses characterized by symptoms like anorexia, fever, diarrhea, and laminitis.
  • The disease is caused by the bacteria Neorickettsia risticii and Neorickettsia findlayensis. Despite existing vaccines, the incidence of PHF is increasing.
  • The current diagnostic methods for PHF using serology or nested PCR cannot distinguish between the two Neorickettsia species causing the disease. Additionally, the currently available real-time PCR tests cannot detect N. findlayensis.
  • The study’s goal was to develop species-specific real-time PCR assays that would be able to distinguish between N. risticii and N. findlayensis and estimate the prevalence of these species in different locations.

Methodology and Findings

  • Real-time PCR assays were developed based on the heat shock protein gene for N. risticii and N. findlayensis respectively. An additional genera-specific real-time PCR was designed based on the 16S rRNA gene of Neorickettsia species.
  • The newly developed tests were able to differentiate N. risticii from N. findlayensis in field samples, confirmed with various other molecular tests and culture isolation methods.
  • The generic 16S rRNA gene-based PCR test was further able to detect both Neorickettsia species in the samples.
  • These tests were further applied to new field isolates from Alberta, Quebec, Ontario, and Ohio, along with archival DNA samples from suspected PHF cases.
  • Results suggested that N. findlayensis more commonly causes PHF in horses in Alberta and Quebec.

Conclusion and Implications

  • The newly developed real-time PCR tests provide a sensitive, quick, and specific method for diagnosing PHF and distinguishing between its causative agents.
  • These new tests will facilitate fast and targeted treatments to manage PHF in affected horses, potentially contributing to reducing mortality rates.
  • Additionally, the development of these tests could also contribute to designing broad-spectrum vaccines for PHF, covering both the Neorickettsia species causing the disease.

Cite This Article

APA
Budachetri K, Lin M, Yan Q, Chien RC, Hostnik LD, Haanen G, Leclère M, Waybright W, Baird JD, Arroyo LG, Rikihisa Y. (2022). Real-Time PCR Differential Detection of Neorickettsia findlayensis and N. risticii in Cases of Potomac Horse Fever. J Clin Microbiol, 60(7), e0025022. https://doi.org/10.1128/jcm.00250-22

Publication

Journal of clinical microbiology
ISSN: 1098-660X
NlmUniqueID: 7505564
Country: United States
Language: English
Volume: 60
Issue: 7
Pages: e0025022
PII: e00250-22

Researcher Affiliations

Budachetri, Khemraj
  • Laboratory of Molecular, Cellular, and Environmental Rickettsiology, Department of Veterinary Biosciences, College of Veterinary Medicine, Infectious Diseases Institute, The Ohio State Universitygrid.261331.4, Columbus, Ohio, USA.
Lin, Mingqun
  • Laboratory of Molecular, Cellular, and Environmental Rickettsiology, Department of Veterinary Biosciences, College of Veterinary Medicine, Infectious Diseases Institute, The Ohio State Universitygrid.261331.4, Columbus, Ohio, USA.
Yan, Qi
  • Laboratory of Molecular, Cellular, and Environmental Rickettsiology, Department of Veterinary Biosciences, College of Veterinary Medicine, Infectious Diseases Institute, The Ohio State Universitygrid.261331.4, Columbus, Ohio, USA.
Chien, Rory C
  • Laboratory of Molecular, Cellular, and Environmental Rickettsiology, Department of Veterinary Biosciences, College of Veterinary Medicine, Infectious Diseases Institute, The Ohio State Universitygrid.261331.4, Columbus, Ohio, USA.
Hostnik, Laura D
  • Veterinary Clinical Sciences, The Ohio State Universitygrid.261331.4, Columbus, Ohio, USA.
Haanen, Gillian
  • Moore Equine Veterinary Centre, Rocky View County, Alberta, Canada.
Leclère, Mathilde
  • Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Montréal, St. Hyacinthe, Québec, Canada.
Waybright, Warren
  • Service Vétérinaire Ambulatoire, St-Lazare, Québec, Canada.
Baird, John D
  • Department of Clinical Studies, Ontario Veterinary College, University of Guelphgrid.34429.38, Guelph, Ontario, Canada.
Arroyo, Luis G
  • Department of Clinical Studies, Ontario Veterinary College, University of Guelphgrid.34429.38, Guelph, Ontario, Canada.
Rikihisa, Yasuko
  • Laboratory of Molecular, Cellular, and Environmental Rickettsiology, Department of Veterinary Biosciences, College of Veterinary Medicine, Infectious Diseases Institute, The Ohio State Universitygrid.261331.4, Columbus, Ohio, USA.

MeSH Terms

  • Anaplasmataceae Infections / diagnosis
  • Anaplasmataceae Infections / microbiology
  • Anaplasmataceae Infections / veterinary
  • Animals
  • Ehrlichia / genetics
  • Horse Diseases / diagnosis
  • Horse Diseases / microbiology
  • Horses / genetics
  • Neorickettsia / genetics
  • Ontario
  • RNA, Ribosomal, 16S / genetics
  • Real-Time Polymerase Chain Reaction
  • Rickettsia Infections

Grant Funding

  • OSU | College of Veterinary Medicine, Ohio State University (CVM, OSU)

Conflict of Interest Statement

The authors declare no conflict of interest.

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Citations

This article has been cited 1 times.
  1. Thirumalapura NR, Livengood J, Beeby J, Wang W, Goodrich EL, Goodman LB, Erol E, Tewari D. Improved molecular detection of Neorickettsia risticii with a duplex real-time PCR assay in the diagnosis of Potomac horse fever.. J Vet Diagn Invest 2023 Jan;35(1):62-66.
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