FREE SHIPPING over $40
OVER 10000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Applied and environmental microbiology2016; 82(19); 6030-6036; doi: 10.1128/AEM.01366-16

An Ecotype of Neorickettsia risticii Causing Potomac Horse Fever in Canada.

Abstract: Neorickettsia (formerly Ehrlichia) risticii is an obligatory intracellular bacterium of digenetic trematodes. When a horse accidentally ingests aquatic insects containing encysted trematodes infected with N. risticii, the bacterium is transmitted from trematodes to horse cells and causes an acute and often fatal disease called Potomac horse fever (PHF). Since the discovery of N. risticii in the United States in 1984, using immunofluorescence and PCR assays, PHF has been increasingly recognized throughout North America and South America. However, so far, there exist only a few stable N. risticii culture isolates, all of which are from horses within the United States, and the strain diversity and environmental spreading and distribution of pathogenic N. risticii strains remain poorly understood. This paper reports the isolation of N. risticii from the blood of a horse with acute PHF in Ontario, Canada. Intracellular N. risticii colonies were detected in P388D1 cells after 47 days of culturing and 8 days after the addition of rapamycin. Molecular phylogenetic analysis based on amino acid sequences of major surface proteins P51 and Ssa1 showed that this isolate is distinct from any previously sequenced strains but closely related to midwestern U.S. strains. This is the first Canadian strain cultured, and a new method was developed to reactivate dormant N. risticii to improve culture isolation. Neorickettsia risticii is an environmental bacterium that lives inside flukes that are parasitic to aquatic snails, insects, and bats. When a horse accidentally ingests insects harboring flukes infected with N. risticii, the bacterium is transmitted to the horse and causes an acute and often fatal disease called Potomac horse fever. Although the disease has been increasingly recognized throughout North and South America, N. risticii has not been cultured outside the United States. This paper reports the first Canadian strain cultured and a new method to effectively culture isolate N. risticii from the horse blood sample. Molecular analysis showed that the genotype of this Canadian strain is distinct from previously sequenced strains but closely related to midwestern U.S. strains. Culture isolation of N. risticii strains would confirm the geographic presence of pathogenic N. risticii, help elucidate N. risticii strain diversity and environmental spreading and distribution, and improve diagnosis and development of vaccines for this dreadful disease.
Copyright © 2016, American Society for Microbiology. All Rights Reserved.
Get Full Text
Publication Date: 2016-09-16 PubMed ID: 27474720PubMed Central: PMC5038023DOI: 10.1128/AEM.01366-16Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Case Reports
  • Journal Article

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 research focuses on the discovery of a unique strain of Neorickettsia risticii in Canada, which is the cause of a severe equine disease called Potomac horse fever. The paper is also an exploration of a new method for culturing this bacterium for further studies.

Background of the Research

  • This study is centered around an infectious bacterium, Neorickettsia risticii, which is responsible for causing Potomac horse fever, a severe and often fatal illness in horses.
  • The bacterium lives inside flukes, parasitic organisms that infest aquatic animals like snails, insects, and bats. The transmission to horses occurs when these hosts, specifically insects, are accidentally ingested by the horse.
  • Although the disease has been prevalent in North and South America, all cultured isolates of this bacterium, to date, have originated from the United States. The study of strain diversity and ecological distribution is thus limited due to a lack of varied samples.

Discovery in Canada

  • The research marks the first successful cultivation of a Neorickettsia risticii strain from Canada. The isolate was extracted from the blood of a horse suffering from acute Potomac horse fever in Ontario.
  • The Canadian strain was found to be genetically distinct from previously analyzed strains but shared close relations to those found in midwestern U.S.
  • Intracellular colonies of N. risticii were detected in the horse blood sample after 47 days of culture and 8 days post addition of rapamycin, an antibacterial agent.

Significance of the Research

  • This discovery amplifies the understanding of the geographical presence of pathogenic N. risticii. This knowledge helps uncover elements about the strain diversity and spread of this bacterium.
  • A new method of culture isolation was developed during the study for reactivation of dormant bacteria. This technique can prove pivotal in facilitating future laboratory research and development of potential vaccines against the disease.
  • The researchers conducted a molecular phylogenetic analysis based on amino acid sequences of major surface proteins P51 and Ssa1 of the bacterium which further contributed to the understanding of its genetic diversity.

Imminent Research Directions

  • The successful culture of a Canadian strain propels the need for more extensive sampling from different geographic locations. This will facilitate a better understanding of the bacterium’s strain diversity, environmental spread, and distribution.
  • Further research could also delve into the development of diagnostic tools and vaccines to prevent Potomac horse fever.

Cite This Article

APA
Xiong Q, Bekebrede H, Sharma P, Arroyo LG, Baird JD, Rikihisa Y. (2016). An Ecotype of Neorickettsia risticii Causing Potomac Horse Fever in Canada. Appl Environ Microbiol, 82(19), 6030-6036. https://doi.org/10.1128/AEM.01366-16

Publication

Applied and environmental microbiology
ISSN: 1098-5336
NlmUniqueID: 7605801
Country: United States
Language: English
Volume: 82
Issue: 19
Pages: 6030-6036

Researcher Affiliations

Xiong, Qingming
  • Laboratory of Molecular, Cellular, and Environmental Rickettsiology, Department of Veterinary Biosciences, College of Veterinary Medicine, Columbus, Ohio, USA.
Bekebrede, Hannah
  • Laboratory of Molecular, Cellular, and Environmental Rickettsiology, Department of Veterinary Biosciences, College of Veterinary Medicine, Columbus, Ohio, USA.
Sharma, Pratibha
  • Laboratory of Molecular, Cellular, and Environmental Rickettsiology, Department of Veterinary Biosciences, College of Veterinary Medicine, Columbus, Ohio, USA.
Arroyo, Luis G
  • Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
Baird, John D
  • Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
Rikihisa, Yasuko
  • Laboratory of Molecular, Cellular, and Environmental Rickettsiology, Department of Veterinary Biosciences, College of Veterinary Medicine, Columbus, Ohio, USA Rikihisa.1@osu.edu.

MeSH Terms

  • Anaplasmataceae Infections / blood
  • Anaplasmataceae Infections / microbiology
  • Anaplasmataceae Infections / veterinary
  • Animals
  • Antigens, Bacterial / blood
  • Bacteriological Techniques / veterinary
  • Ecotype
  • Horse Diseases / blood
  • Horse Diseases / microbiology
  • Horses
  • Male
  • Neorickettsia risticii / genetics
  • Neorickettsia risticii / immunology
  • Neorickettsia risticii / isolation & purification
  • Ontario
  • Phylogeny
  • Sequence Analysis, DNA / veterinary
  • Treatment Outcome

References

This article includes 31 references
  1. Rikihisa Y, Dumler JS, Dasch GA. Neorickettsia. Bergey's manual of systematic bacteriology vol 2: the Proteobacteria, part C, p 132–138, 2005.
  2. Vaughan JA, Tkach VV, Greiman SE. Neorickettsial endosymbionts of the digenea: diversity, transmission and distribution.. Adv Parasitol 2012;79:253-97.
    doi: 10.1016/B978-0-12-398457-9.00003-2pubmed: 22726644google scholar: lookup
  3. Holland CJ, Ristic M, Cole AI, Johnson P, Baker G, Goetz T. Isolation, experimental transmission, and characterization of causative agent of Potomac horse fever.. Science 1985 Feb 1;227(4686):522-4.
    doi: 10.1126/science.3880925pubmed: 3880925google scholar: lookup
  4. Rikihisa Y, Perry B, Cordes D. Rickettsial link with acute equine diarrhoea.. Vet Rec 1984 Oct 13;115(15):390.
    doi: 10.1136/vr.115.15.390-apubmed: 6506415google scholar: lookup
  5. Kanter M, Mott J, Ohashi N, Fried B, Reed S, Lin YC, Rikihisa Y. Analysis of 16S rRNA and 51-kilodalton antigen gene and transmission in mice of Ehrlichia risticii in virgulate trematodes from Elimia livescens snails in Ohio.. J Clin Microbiol 2000 Sep;38(9):3349-58.
    pmc: PMC87385pubmed: 10970382doi: 10.1128/jcm.38.9.3349-3358.2000google scholar: lookup
  6. Reubel GH, Barlough JE, Madigan JE. Production and characterization of Ehrlichia risticii, the agent of Potomac horse fever, from snails (Pleuroceridae: Juga spp.) in aquarium culture and genetic comparison to equine strains.. J Clin Microbiol 1998 Jun;36(6):1501-11.
    pmc: PMC104868pubmed: 9620368doi: 10.1128/jcm.36.6.1501-1511.1998google scholar: lookup
  7. Chae JS, Pusterla N, Johnson E, Derock E, Lawler SP, Madigan JE. Infection of aquatic insects with trematode metacercariae carrying Ehrlichia risticii, the cause of Potomac horse fever.. J Med Entomol 2000 Jul;37(4):619-25.
    doi: 10.1603/0022-2585-37.4.619pubmed: 10916305google scholar: lookup
  8. Mott J, Muramatsu Y, Seaton E, Martin C, Reed S, Rikihisa Y. Molecular analysis of Neorickettsia risticii in adult aquatic insects in Pennsylvania, in horses infected by ingestion of insects, and isolated in cell culture.. J Clin Microbiol 2002 Feb;40(2):690-3.
    doi: 10.1128/JCM.40.2.690-693.2002pmc: PMC153368pubmed: 11825999google scholar: lookup
  9. Gibson KE, Rikihisa Y, Zhang C, Martin C. Neorickettsia risticii is vertically transmitted in the trematode Acanthatrium oregonense and horizontally transmitted to bats.. Environ Microbiol 2005 Feb;7(2):203-12.
    doi: 10.1111/j.1462-2920.2004.00683.xpubmed: 15658987google scholar: lookup
  10. Pusterla N, Johnson EM, Chae JS, Madigan JE. Digenetic trematodes, Acanthatrium sp. and Lecithodendrium sp., as vectors of Neorickettsia risticii, the agent of Potomac horse fever.. J Helminthol 2003 Dec;77(4):335-9.
    doi: 10.1079/JOH2003181pubmed: 14627451google scholar: lookup
  11. Park BK, Kim MJ, Kim EH, Kim MS, Na DG, Chae JS. Identification of trematode cercariae carrying Neorickettsia risticii in freshwater stream snails.. Ann N Y Acad Sci 2003 Jun;990:239-47.
    doi: 10.1111/j.1749-6632.2003.tb07371.xpubmed: 12860634google scholar: lookup
  12. Greiman SE, Tkach VV, Vaughan JA. Transmission rates of the bacterial endosymbiont, Neorickettsia risticii, during the asexual reproduction phase of its digenean host, Plagiorchis elegans, within naturally infected lymnaeid snails.. Parasit Vectors 2013 Oct 22;6:303.
    doi: 10.1186/1756-3305-6-303pmc: PMC3924192pubmed: 24383453google scholar: lookup
  13. Madigan JE, Pusterla N, Johnson E, Chae JS, Pusterla JB, Derock E, Lawler SP. Transmission of Ehrlichia risticii, the agent of Potomac horse fever, using naturally infected aquatic insects and helminth vectors: preliminary report.. Equine Vet J 2000 Jul;32(4):275-9.
    doi: 10.2746/042516400777032219pubmed: 10952374google scholar: lookup
  14. Rikihisa Y. Rickettsial diseases. Equine internal medicine 2nd ed, 2004.
  15. Biswas B, Vemulapalli R, Dutta SK. Molecular basis for antigenic variation of a protective strain-specific antigen of Ehrlichia risticii.. Infect Immun 1998 Aug;66(8):3682-8.
    pmc: PMC108402pubmed: 9673249doi: 10.1128/iai.66.8.3682-3688.1998google scholar: lookup
  16. Chaichanasiriwithaya W, Rikihisa Y, Yamamoto S, Reed S, Crawford TB, Perryman LE, Palmer GH. Antigenic, morphologic, and molecular characterization of new Ehrlichia risticii isolates.. J Clin Microbiol 1994 Dec;32(12):3026-33.
    pmc: PMC264219pubmed: 7533780doi: 10.1128/jcm.32.12.3026-3033.1994google scholar: lookup
  17. Gibson KE, Pastenkos G, Moesta S, Rikihisa Y. Neorickettsia risticii surface-exposed proteins: proteomics identification, recognition by naturally-infected horses, and strain variations.. Vet Res 2011 Jun 2;42(1):71.
    doi: 10.1186/1297-9716-42-71pmc: PMC3127766pubmed: 21635728google scholar: lookup
  18. Mott J, Rikihisa Y, Zhang Y, Reed SM, Yu CY. Comparison of PCR and culture to the indirect fluorescent-antibody test for diagnosis of Potomac horse fever.. J Clin Microbiol 1997 Sep;35(9):2215-9.
    pmc: PMC229942pubmed: 9276390doi: 10.1128/jcm.35.9.2215-2219.1997google scholar: lookup
  19. Wen B, Rikihisa Y, Fuerst PA, Chaichanasiriwithaya W. Diversity of 16S rRNA genes of new Ehrlichia strains isolated from horses with clinical signs of Potomac horse fever.. Int J Syst Bacteriol 1995 Apr;45(2):315-8.
    doi: 10.1099/00207713-45-2-315pubmed: 7537065google scholar: lookup
  20. Palmer JE. Prevention of Potomac horse fever.. Cornell Vet 1989 Jul;79(3):201-5.
    pubmed: 2666021
  21. Schofield F. An investigation into an endemic disease of horses (occurring chiefly in Kent and Essex counties of the Province of Ontario). Rep Ontario Veterinary College 1924 1925:41–49.
  22. Baird JD, Arroyo LG. Historical aspects of Potomac horse fever in Ontario (1924-2010).. Can Vet J 2013 Jun;54(6):565-72.
    pmc: PMC3659452pubmed: 24155447
  23. Rikihisa Y, Zhang C, Kanter M, Cheng Z, Ohashi N, Fukuda T. Analysis of p51, groESL, and the major antigen P51 in various species of Neorickettsia, an obligatory intracellular bacterium that infects trematodes and mammals.. J Clin Microbiol 2004 Aug;42(8):3823-6.
    doi: 10.1128/JCM.42.8.3823-3826.2004pmc: PMC497601pubmed: 15297539google scholar: lookup
  24. Pusterla N, Madigan JE, Chae JS, DeRock E, Johnson E, Pusterla JB. Helminthic transmission and isolation of Ehrlichia risticii, the causative agent of Potomac horse fever, by using trematode stages from freshwater stream snails.. J Clin Microbiol 2000 Mar;38(3):1293-7.
    pmc: PMC88611pubmed: 10699046doi: 10.1128/jcm.38.3.1293-1297.2000google scholar: lookup
  25. Dutta SK, Vemulapalli R, Biswas B. Association of deficiency in antibody response to vaccine and heterogeneity of Ehrlichia risticii strains with Potomac horse fever vaccine failure in horses.. J Clin Microbiol 1998 Feb;36(2):506-12.
    pmc: PMC104568pubmed: 9466767doi: 10.1128/jcm.36.2.506-512.1998google scholar: lookup
  26. Vemulapalli R, Biswas B, Dutta SK. Cloning and molecular analysis of genes encoding two immunodominant antigens of Ehrlichia risticii.. Microb Pathog 1998 Jun;24(6):361-72.
    doi: 10.1006/mpat.1998.0208pubmed: 9632540google scholar: lookup
  27. Vemulapalli R, Biswas B, Dutta SK. Studies with recombinant proteins of Ehrlichia risticii: identification of strain-specific antigen as a protective antigen.. Vet Parasitol 1998 Apr 15;76(3):189-202.
    doi: 10.1016/S0304-4017(97)00209-4pubmed: 9615953google scholar: lookup
  28. Purtle L, Mellencamp M, Vaala W. Potomac horse fever isolates. U.S. patent US 2012/0052091 Al, March 2012.
  29. Inoki K, Ouyang H, Li Y, Guan KL. Signaling by target of rapamycin proteins in cell growth control.. Microbiol Mol Biol Rev 2005 Mar;69(1):79-100.
    doi: 10.1128/MMBR.69.1.79-100.2005pmc: PMC1082789pubmed: 15755954google scholar: lookup
  30. Niu H, Yamaguchi M, Rikihisa Y. Subversion of cellular autophagy by Anaplasma phagocytophilum.. Cell Microbiol 2008 Mar;10(3):593-605.
    doi: 10.1111/j.1462-5822.2007.01068.xpubmed: 17979984google scholar: lookup
  31. Rikihisa Y. New findings on members of the family Anaplasmataceae of veterinary importance.. Ann N Y Acad Sci 2006 Oct;1078:438-45.
    doi: 10.1196/annals.1374.083pubmed: 17114752google scholar: lookup

Citations

This article has been cited 5 times.
  1. Budachetri K, Lin M, Yan Q, Chien RC, Hostnik LD, Haanen G, Leclère M, Waybright W, Baird JD, Arroyo LG, Rikihisa Y. Real-Time PCR Differential Detection of Neorickettsia findlayensis and N. risticii in Cases of Potomac Horse Fever. J Clin Microbiol 2022 Jul 20;60(7):e0025022.
    doi: 10.1128/jcm.00250-22pubmed: 35695520google scholar: lookup
  2. Arroyo LG, Moore A, Bedford S, Gomez DE, Teymournejad O, Xiong Q, Budachetri K, Bekebrede H, Rikihisa Y, Baird JD. Potomac horse fever in Ontario: Clinical, geographic, and diagnostic aspects. Can Vet J 2021 Jun;62(6):622-628.
    pubmed: 34219771
  3. Teymournejad O, Lin M, Bekebrede H, Kamr A, Toribio RE, Arroyo LG, Baird JD, Rikihisa Y. Isolation and Molecular Analysis of a Novel Neorickettsia Species That Causes Potomac Horse Fever. mBio 2020 Feb 25;11(1).
    doi: 10.1128/mBio.03429-19pubmed: 32098825google scholar: lookup
  4. Shaw SD, Stämpfli H. Diagnosis and Treatment of Undifferentiated and Infectious Acute Diarrhea in the Adult Horse. Vet Clin North Am Equine Pract 2018 Apr;34(1):39-53.
    doi: 10.1016/j.cveq.2017.11.002pubmed: 29426709google scholar: lookup
  5. Fortin-Trahan R, Sjolin E, Lack A, de Arbina CL, McFadden-Bennett A, Wang L, Baird JD, Rikihisa Y, Arroyo LG. Diagnosis of Potomac horse fever (syn. equine neorickettsiosis) in 2 foals in southwestern Ontario. Can Vet J 2023 Dec;64(12):1129-1132.
    pubmed: 38046433
Subscribe to our newsletter
Join 99,911 horse owners like you who receive our email updates on horse health and nutrition.