Horses vaccinated with live attenuated intranasal strangles vaccine seroconvert to SEQ2190 and SeM.
Abstract: The dual antigen iELISA uses two Streptococcus equi subsp equi surface protein antigens composed of N-terminal portions of SEQ2190 (Antigen A) and SeM (Antigen C). It is currently used to identify animals exposed to S. equi which have developed an immune response to the target antigens. Objective: To determine the usefulness of the dual antigen iELISA in a population of horses vaccinated with Pinnacle IN. We hypothesised that horses vaccinated for strangles with a live attenuated, non-encapsulated SeM-2 strain of S. equi, would seroconvert when tested 5 weeks later by the dual antigen iELISA. Methods: Prospective case-control study. Methods: Three separate serum samples were obtained from 26 client-owned horses vaccinated annually with Pinnacle IN and 26 university-owned (non-vaccinates): at annual strangles vaccination (S1), 5-week post-vaccination (S2) from vaccinates, and a third (S3) (at 10 weeks) from vaccinates who received a booster. Seropositivity was defined as an OD450 nm value ≥0.5 for one or both antigens. Mixed-effects ordered logistic regression analysis was used to identify factors associated with a suspect seropositive and seropositive value on the combined Antigen A and Antigen C iELISA. Post hoc pairwise comparisons of linear predictive margins were used to assess the differences in OD450 at a specific time between Antigens A and C. Results: Nineteen of 25 (76%) vaccinates were seropositive at S2 compared to 1 of 26 (4%) non-vaccinates. When adjusted for sample number, vaccinates were more likely to be seropositive or suspect than non-vaccinates (OR 14; P = .02, 95% CI 1.62-122.03). The OD450 value was significantly larger for Antigen C than Antigen A for vaccinates (P < .001; 95% CI 0.13-0.26) when normalised by age, sex and breed. Conclusions: Guttural pouch sampling for S. equi in seroconverted horses was unavailable. Conclusions: With a high rate of seroconversion to both antigens, the use of the dual antigen iELISA is not recommended in populations vaccinated with Pinnacle IN.
© 2021 EVJ Ltd.
Publication Date: 2021-03-18 PubMed ID: 33630353DOI: 10.1111/evj.13443Google Scholar: Lookup
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- Journal Article
Summary
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The research article explores how horses that are vaccinated with a live attenuated intranasal strangles vaccine (Pinnacle IN) react to a dual antigen iELISA, a test used to identify animals that have been exposed to bacteria Streptococcus equi and developed an immune response.
About the iELISA Test
- The iELISA test uses two antigens, SEQ2190 (Antigen A) and SeM (Antigen C), which are made from surface proteins of the Streptococcus equi bacteria.
- The test is intended to identify whether the examined animal has been exposed to the bacterium and has formed an immune response against it.
Objective and Methodology of the Study
- The researchers aimed to determine how effective the iELISA test is when applied to a group of horses vaccinated with Pinnacle IN.
- They hypothesized that the horses vaccinated with this particular strain would show a positive immune response (seroconvert) when tested 5 weeks after the vaccination.
- The study monitored 26 client-owned horses that were given annual Pinnacle IN vaccinations (vaccinates) and 26 university-owned horses that were not vaccinated (non-vaccinates).
- Three serum samples were collected from the vaccinated horses: at the time of the annual vaccination, 5 weeks after the vaccination, and 10 weeks after the vaccination following a booster shot.
- An OD450 nm value of more than or equal to 0.5 for one or both antigens was considered a positive immune response (seropositivity).
- The researchers used statistical analysis to find factors related to a suspected or positive immune response.
Results of the Study
- Of the vaccinated horses, 76% were seropositive 5 weeks after the vaccination while only 4% of the non-vaccinated horses were seropositive.
- Even after adjusting for sample number, the vaccinated horses were more likely to be seropositive or suspect than the non-vaccinated horses.
- Antigen C resulted in a significantly higher OD450 value than Antigen A among the vaccinated horses, after normalizing for age, sex, and breed.
Conclusions
- The researchers were unable to sample the guttural pouch to check for the presence of S. equi in seroconverted horses.
Cite This Article
APA
Boyle AG, Mitchell C, Stefanovski D, Waller AS.
(2021).
Horses vaccinated with live attenuated intranasal strangles vaccine seroconvert to SEQ2190 and SeM.
Equine Vet J, 54(2), 299-305.
https://doi.org/10.1111/evj.13443 Publication
Researcher Affiliations
- Department of Clinical Studies New Bolton Center, University of Pennsylvania, Kennett Square, PA, USA.
- Department of Microbiology, Animal Health Trust, Kentford, Newmarket, Suffolk, UK.
- Department of Clinical Studies New Bolton Center, University of Pennsylvania, Kennett Square, PA, USA.
- Department of Microbiology, Animal Health Trust, Kentford, Newmarket, Suffolk, UK.
- Intervacc AB, Hägersten, Sweden.
MeSH Terms
- Animals
- Case-Control Studies
- Horse Diseases / prevention & control
- Horses
- Streptococcal Infections / prevention & control
- Streptococcal Infections / veterinary
- Streptococcus equi
- Vaccines
Grant Funding
- University of Pennsylvania
- Clinical Studies New Bolton Center
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This article includes 20 references
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Citations
This article has been cited 4 times.- Jaramillo-Morales C, James K, Barnum S, Vaala W, Chappell DE, Schneider C, Craig B, Bain F, Barnett DC, Gaughan E, Pusterla N. Voluntary Biosurveillance of Streptococcus equi Subsp. equi in Nasal Secretions of 9409 Equids with Upper Airway Infection in the USA. Vet Sci 2023 Jan 20;10(2).
- Martin KH, Redding LE, Boyle AG. Factors Influencing Veterinarian Opinion on Reporting of Equine Strangles in the United States. J Equine Vet Sci 2022 Jul;114:103947.
- Frosth S, Morris ERA, Wilson H, Frykberg L, Jacobsson K, Parkhill J, Flock JI, Wood T, Guss B, Aanensen DM, Boyle AG, Riihimäki M, Cohen ND, Waller AS. Conservation of vaccine antigen sequences encoded by sequenced strains of Streptococcus equi subsp. equi. Equine Vet J 2023 Jan;55(1):92-101.
- Wan J, Weldon E, Ganser G, Morris ERA, Hughes EV, Bordin AI, Heine PA, Hust M, Cohen ND, Gill JJ, Liu M. Immunogenic Streptococcus equi cell surface proteins identified by ORFeome phage display. mSphere 2025 Dec 23;10(12):e0062625.
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