Decreased Clinical Severity of Strangles in Weanlings Associated with Restricted Seroconversion to Optimized Streptococcus equi ssp equi Assays
| Autor: | M. Venner, Karen F. Steward, Lisa Tscheschlok, Miia Riihimäki, John Pringle, R. Böse |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Male Streptococcus equi 040301 veterinary sciences Immunology Virulence Enzyme-Linked Immunosorbent Assay Standard Article Polymerase Chain Reaction Serology Disease Outbreaks 0403 veterinary science 03 medical and health sciences Antigen Streptococcal Infections SeM antigen Medicine Animals Horses Prospective Studies Seroconversion Strangles General Veterinary business.industry Antigen C Outbreak Antigen A 04 agricultural and veterinary sciences Standard Articles qPCR 030104 developmental biology Warmblood Female Horse Diseases EQUID Nasal Cavity business |
| Zdroj: | Journal of Veterinary Internal Medicine |
| ISSN: | 1939-1676 0891-6640 |
| Popis: | Background Streptococcus equi ssp. equi causes characteristic clinical signs that are most severe in young horses, including fever, purulent nasal discharge, and lymph node abscessation in the head region. Hypothesis/objectives Clinical, serologic, and microbiologic factors related to unexpectedly mild disease severity in a natural outbreak of strangles in immunologically naive weanlings were investigated. Animals One-hundred and twelve warmblood weanlings. Methods Prospective longitudinal observational study of a natural outbreak of strangles. The entire cohort was examined at the peak of the outbreak by deep nasal swabs for culture and quantitative PCR (qPCR) for the presence of S. equi and clinically and serologically in a sequential manner by an optimized ELISA from the index case throughout the outbreak until resolution. Descriptive statistics were calculated and comparisons made using a nondirectional Wilcoxon signed-rank test. Results Outbreak morbidity was 53%, with 9 of 14 horses culture positive and 26 of 53 horses qPCR positive for S. equi lacking clinical signs characteristic of strangles. By resolution, 91 of 112 had seroconverted to Antigen A by ELISA but seroconversion to antigen C (part of the SeM protein) was minimal. Sequencing of the isolates detected no alterations in the SeM protein, but identified a 61 bp deletion in the gene SEQ_0402. Conclusions and clinical importance Absence of clinical signs alone in naive horses may be an insufficient criterion to release horses from strangles quarantine measures. Restricted seroconversion to antigen C may have been associated with decreased clinical severity. The role of a minor gene deletion in SEQ_0402 in the virulence of S. equi warrants further investigation. |
| Databáze: | OpenAIRE |
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