Differences in the genome, methylome, and transcriptome do not differentiate isolates of Streptococcus equi subsp. equi from horses with acute clinical signs from isolates of inapparent carriers.
Abstract: Streptococcus equi subsp. equi (SEE) is a host-restricted bacterium that causes the common infectious upper respiratory disease known as strangles in horses. Perpetuation of SEE infection appears attributable to inapparent carrier horses because it neither persists long-term in the environment nor infects other host mammals or vectors, and infection results in short-lived immunity. Whether pathogen factors enable SEE to remain in horses without causing clinical signs remains poorly understood. Thus, our objective was to use next-generation sequencing technologies to characterize the genome, methylome, and transcriptome of isolates of SEE from horses with acute clinical strangles and inapparent carrier horses-including isolates recovered from individual horses sampled repeatedly-to assess pathogen-associated changes that might reflect specific adaptions of SEE to the host that contribute to inapparent carriage. The accessory genome elements and methylome of SEE isolates from Sweden and Pennsylvania revealed no significant or consistent differences between acute clinical and inapparent carrier isolates of SEE. RNA sequencing of SEE isolates from Pennsylvania demonstrated no genes that were differentially expressed between acute clinical and inapparent carrier isolates of SEE. The absence of specific, consistent changes in the accessory genomes, methylomes, and transcriptomes of acute clinical and inapparent carrier isolates of SEE indicates that adaptations of SEE to the host are unlikely to explain the carrier state of SEE. Efforts to understand the carrier state of SEE should instead focus on host factors.
Publication Date: 2021-06-14 PubMed ID: 34125848PubMed Central: PMC8202921DOI: 10.1371/journal.pone.0252804Google 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.
This study focuses on the bacterium Streptococcus equi subsp. equi (SEE), which causes a common upper respiratory disease in horses known as strangles. It explored whether the pathogen had specific traits enabling it to live in carriers without causing symptoms, but found no significant differences in the genome, methylome or transcriptome of SEE isolates from infected horses and asymptomatic carriers, thereby suggesting host factors should be the focus of further research.
Context and Objective
- The bacterium SEE causes a common infectious respiratory disease in horses called strangles. Ongoing infections seem to be maintained by symptomless carriers. The manner in which SEE manages to exist in hosts without causing symptoms remains unclear. The objective of this research was to better understand these potential pathogen factors.
The Study
- The researchers collected and analyzed isolates of SEE derived from horses showing acute clinical signs of strangles and asymptomatic carriers. Data was also included from isolates recovered from the same horses over time.
- Genome, methylome, and transcriptome – the three key aspects of cellular functionality – of the SEE isolates were studied using advanced next-generation sequencing technologies.
- This study was aimed at identifying any potential pathogen-associated changes in the SEE isolates that might point to specific adaptations enabling the bacteria to persistently reside in carriers without showing clinical signs.
Findings
- The study did not find any significant or consistent differences in the genome, methylome, or transcriptome of SEE isolates from acutely sick horses and carrier horses.
- This result was consistent across SEE samples from different geographical locations – Sweden and Pennsylvania.
- The research did not identify any genes that showed differential expression between the acute clinical and asymptomatic carrier isolates of SEE.
Conclusion
- The lack of identifiable changes in the genomics, methylomics, and transcriptomics of SEE isolated from diseased and carrier horses suggests that the pathogen does not likely adapt or change to persist in the host.
- Given these results, the researchers concluded that the focus of further investigations into the underlying mechanisms of the SEE carrier state should shift towards host factors, which could potentially include the host’s immune response or other intrinsic resistance mechanisms.
Cite This Article
APA
Morris ERA, Boyle AG, Riihimäki M, Aspán A, Anis E, Hillhouse AE, Ivanov I, Bordin AI, Pringle J, Cohen ND.
(2021).
Differences in the genome, methylome, and transcriptome do not differentiate isolates of Streptococcus equi subsp. equi from horses with acute clinical signs from isolates of inapparent carriers.
PLoS One, 16(6), e0252804.
https://doi.org/10.1371/journal.pone.0252804 Publication
Researcher Affiliations
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, New Bolton Center, Kennett Square, Pennsylvania, United States of America.
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, New Bolton Center, Kennett Square, Pennsylvania, United States of America.
- Department of Veterinary Pathobiology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
- Texas A&M Institute for Genome Sciences and Society, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
- Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
MeSH Terms
- Animals
- Carrier State / diagnosis
- Carrier State / microbiology
- DNA, Bacterial / analysis
- DNA, Bacterial / genetics
- DNA, Bacterial / isolation & purification
- Diagnosis, Differential
- Disease Outbreaks
- Epigenome / genetics
- Genome / genetics
- Horse Diseases / diagnosis
- Horse Diseases / epidemiology
- Horse Diseases / microbiology
- Horses
- Pennsylvania / epidemiology
- RNA, Bacterial / analysis
- RNA, Bacterial / genetics
- RNA, Bacterial / isolation & purification
- RNA-Seq / methods
- Species Specificity
- Streptococcus / classification
- Streptococcus / genetics
- Streptococcus / physiology
- Sweden / epidemiology
- Transcriptome / genetics
- Whole Genome Sequencing / methods
Conflict of Interest Statement
No authors have competing interests.
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Citations
This article has been cited 2 times.- Rotinsulu DA, Ewers C, Kerner K, Amrozi A, Soejoedono RD, Semmler T, Bauerfeind R. Molecular Features and Antimicrobial Susceptibilities of Streptococcus equi ssp. equi Isolates from Strangles Cases in Indonesia. Vet Sci 2023 Jan 10;10(1).
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