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Updated: Jul 10, 2026
Development and Validation of a Quantitative PCR Method for Equid Herpesvirus-2 Diagnostics in Respiratory Fluids
Published on: March 17, 2016
A new single-antigen serological test accurately detects horses infected with Streptococcus equi subsp equi
Noah D Cohen1, Rie Nakajima2, Ellen Ruth Alexander Morris3
11Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
Objective:
To develop an accurate serological test for detecting horses infected with Streptococcus equi subsp equi (SEE).
Methods:
The study was designed as a prospective experiment. First, 89 proteins either expressed on the surface or secreted by SEE were cloned, expressed in a cell-free culture system, and printed onto a microarray. Microarrays were probed with serum from 30 horses with strangles, 30 horses with no history of infection or immunization against SEE, and 18 horses infected with Streptococcus equi subsp zooepidemicus (SEZ); serum samples were collected between 2020 and 2021 from Texas horses. Informatic analysis identified a novel protein we identified as protein 92 (P92). Serum samples from 102 horses with strangles, 104 control horses, and 24 horses infected with SEZ were tested with indirect ELISA for either P92 or the M protein of SEE (SeM); horses were from various US states collected during 2022 and 2023. Data were analyzed by comparing areas under the receiver operator characteristic curves and by generalized linear modeling to compare antibody activities among groups with the Tukey method for pairwise comparisons.
Results:
The microarray identified a new protein (P92) for strangles testing. The area under the receiver operator characteristic curve for the P92 ELISA (95%; 95% CI, 92% to 98%) was significantly greater than that of the SeM ELISA (88%; 95% CI, 83% to 92%).
Conclusions:
The P92 ELISA improves the accuracy of diagnostic testing for strangles.
Clinical Relevance:
A newly identified protein offers a target for improving strangles diagnostic testing.
