Antigenic, morphologic, and molecular characterization of new Ehrlichia risticii isolates.
Abstract: Ehrlichia risticii causes an acute infectious disease in horses called Potomac horse fever. To investigate the biological diversity of E. risticii organisms, nine E. risticii isolates derived from the peripheral blood monocytes of clinically sick horses in Ohio and Kentucky during the summers of 1991 and 1993 were compared with Illinois and Virginia isolates originally obtained from horses in Maryland in 1984. Seven of the nine isolates (081, 606, 380, 679, As, Co, and Ov) formed large morulae (tightly packed inclusions of ehrlichial organisms). The remaining isolates, including 1984 isolates, were individually dispersed or formed small morulae in the cytoplasm of P388D1 cells. In Western blot (immunoblot) analysis with four equine and one rabbit polyclonal anti-E. risticii sera, these recent E. risticii isolates showed patterns of antigenic proteins distinct from those of the 1984 isolates and could be divided into three groups: (i) 081; (ii) 606, 022, 067, 380, and 679; and (iii) As, Co, and Ov. By indirect fluorescent antibody labeling with two panels of murine anti-E. risticii (Illinois and Maryland isolates) monoclonal antibodies, isolate 081 was not labeled with any of 20 monoclonal antibodies tested. The remaining isolates were not labeled with several monoclonal antibodies. The digestion pattern with one of the restriction enzymes, AvaII, of the PCR-amplified partial 16S rRNA gene of E. risticii from all Kentucky isolates (As, Co, and Ov) was different from that of Illinois, Virginia, and six Ohio isolates. These results indicate the presence of distinct variants of E. risticii which vary significantly in morphology, antigenic composition, and the base sequence of the 16S rRNA gene.
Publication Date: 1994-12-01 PubMed ID: 7533780PubMed Central: PMC264219DOI: 10.1128/jcm.32.12.3026-3033.1994Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- Non-P.H.S.
Summary
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This research investigates the biological diversity of Ehrlichia risticii, a bacteria causing infectious disease in horses, across new isolates from Ohio and Kentucky. The study suggests these new isolates display significant variation in morphology, antigenic composition, and 16S rRNA gene sequencing.
Objective of Research
The researchers aim to understand diversity in Ehrlichia risticii, a organism that causes Potomac horse fever, by comparing new isolates to earlier ones from Illinois and Virginia. This helps in understanding the genetic and morphological variability of this organism in different geographical locations and timeframes.
Methodology
- The scientists collected nine isolates from the blood of ill horses in Kentucky and Ohio in the summers of 1991 and 1993. They compared these to isolates acquired in Maryland in 1984.
- Seven of nine new isolates exhibited more significant morulae, or clusters of bacteria, compared to the 1984 isolates. The remaining had either isolated germs or smaller clusters.
- They conducted a Western blot analysis using horse and rabbit anti-E. risticii sera to see how the newly isolated groups reacted to these sera. They observed distinct antigenic protein patterns, categorizing the isolates into three groups.
- The reactivity to two different sets of monoclonal antibodies was analyzed using an Indirect Fluorescent Antibody Labeling procedure. Here isolate 081 did not re-act with any antibodies tested, indicting it has a different antigenic composition.
- A molecular comparison was made by amplifying and analyzing the 16S rRNA gene using a PCR (Polymerase Chain Reaction) method and the restriction enzyme AvaII. The resulting patterns differed between isolates collected from Kentucky and those from Illinois, Virginia, and Ohio.
Results and Conclusion
- The new isolates exhibited unique patterns of large morulae, distinguishing them from older 1984 isolates.
- Considerable diversity was observed in antigenic protein patterns of new isolates, underscoring three distinct groupings.
- The indirect fluorescent antibody labeling showed varied reactivity with isolate 081 not showing reaction with any tested antibodies.
- PCR amplification and AvaII restriction patterns of 16S rRNA gene confirmed distinct genetic variability between the different geographical isolate groups.
- Synthesis of these results reinforced the conclusion of biological diversity in E. risticii isolates, reflected in significant variations in morphological, genetic, and antigenic features.
Cite This Article
APA
Chaichanasiriwithaya W, Rikihisa Y, Yamamoto S, Reed S, Crawford TB, Perryman LE, Palmer GH.
(1994).
Antigenic, morphologic, and molecular characterization of new Ehrlichia risticii isolates.
J Clin Microbiol, 32(12), 3026-3033.
https://doi.org/10.1128/jcm.32.12.3026-3033.1994 Publication
Researcher Affiliations
- Department of Veterinary Pathobiology, Ohio State University, Columbus 43210-1093.
MeSH Terms
- Animals
- Ehrlichia / genetics
- Ehrlichia / immunology
- Ehrlichia / ultrastructure
- Ehrlichiosis / microbiology
- Ehrlichiosis / veterinary
- Horse Diseases / microbiology
- Horses
- Mice
- Polymerase Chain Reaction
- RNA, Bacterial / genetics
- RNA, Ribosomal, 16S / genetics
- Rabbits
- Sequence Analysis, RNA
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This article includes 15 references
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Citations
This article has been cited 19 times.- 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.
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