Immunization but not natural infection of horses results in antibody activity against the S protein of Streptococcus equi subsp equi.
Abstract: Evaluate the immunogenicity of a vaccine targeting the S protein (Ssee) of Streptococcus equi subsp equi and determine antibody activity against Ssee in horses with strangles. Methods: The study was designed as a prospective experiment using 20 university-owned Quarter Horses and a cross-sectional serosurvey of 78 privately owned horses with strangles. Horses were immunized IM with 0 (n = 4), 200 (n = 8), or 400 (n = 8) μg of recombinant Ssee at weeks 0, 4, and 12. Serum and nasal secretions were collected at weeks 0, 4, 6, 12, 16, and 28 and tested by ELISA for immunoglobulin (Ig)-G against Ssee; nasal secretions were also tested for anti-Ssee IgA. The function of anti-Ssee IgG in serum was tested for complement deposition onto Ssee and opsonophagocytic killing of S equi subsp equi. Serum from horses with strangles was tested by ELISA for anti-Ssee IgG activity. Results: Immunization with Ssee significantly (P < .05) increased serum and nasal IgG (but not nasal IgA) against Ssee for up to 12 weeks after the third immunization, and serum from vaccinated horses mediated significantly (P .05), than controls. Horses with strangles did not develop high levels of serum IgG activity against Ssee. Conclusions: Immunizing horses with Ssee resulted in increased activity of functional IgG in serum and nasal secretions, and horses with strangles had very low levels of serum IgG activity against Ssee. Conclusions: S protein has potential as a vaccine to reduce the severity of strangles and differentiate between infected and vaccinated horses.
Publication Date: 2024-12-16 PubMed ID: 39681079DOI: 10.2460/ajvr.24.08.0228Google Scholar: Lookup
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Summary
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The study examines the effectiveness of a vaccine against the S Protein (Ssee) in Streptococcus equi subsp equi in generating immune response in horses. Interestingly, the study finds that while horses immunized with the vaccine see an increase in antibodies, horses naturally infected do not show a large increase in these antibodies.
Research Methodology
- The research was designed as a prospective study using 20 Quarter Horses owned by the university, and a cross-sectional serosurvey of 78 privately owned horses that had strangles, a bacterial infection common in horses.
- Horses were immunized via intramuscular injection with either 0, 200, or 400 micrograms of the recombinant Ssee protein, which is part of the Streptococcus equi subsp equi bacteria, at three different time points (weeks 0, 4, and 12).
- Mucosal and serum samples were taken from the horses at specific points (weeks 0, 4, 6, 12, 16, and 28) to test for the presence of antibodies (IgG and IgA) against Ssee using ELISA, a type of antibody detection assay.
- The functionality of the anti-Ssee IgG in serum was tested through complement deposition onto Ssee, a process which enhances the ability of phagocytes to clear the bacteria, as well as opsonophagocytic killing of the bacteria.
- Additionally, serum from horses with strangles was also tested for antibody activity against the Ssee protein.
Results
- The study found a significant increase in serum and nasal IgG antibody levels against Ssee in horses that had been immunized with the Ssee vaccine, with levels high for up to 12 weeks after the third vaccination.
- While immunized horses exhibited significant complement deposition onto Ssee, indicating a heightened immune response, there was no increase in opsonophagocytic killing of the bacteria.
- Interestingly, horses that had been naturally infected with strangles did not exhibit raised levels of IgG against Ssee, suggesting the natural infection does not generate a strong antibody response like the vaccine does.
Implications
- The results of this study suggest that the S Protein of Streptococcus equi subsp equi could be a potential target for a vaccine to reduce the severity of strangles and to differentiate between horses that have been vaccinated and those that have been naturally infected.
- As natural infection did not raise IgG levels strongly, the study suggests it’s potentially low efficacy in generating immunity against further infections.
Cite This Article
APA
Cohen ND, Hughes EV, Bayne C, Morris ERA, Bray JM, Landrock KK, Gonzales DM, Baker RM, Klein RL, Liu W, Legere RM, Wehmeyer SG, Bordin AI, Wierzbicki IH, Gonzalez DJ.
(2024).
Immunization but not natural infection of horses results in antibody activity against the S protein of Streptococcus equi subsp equi.
Am J Vet Res, 1-11.
https://doi.org/10.2460/ajvr.24.08.0228 Publication
Researcher Affiliations
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
- Department of Pharmacology, School of Medicine, University of California-San Diego, La Jolla, CA.
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego, La Jolla, CA.
- Center for Microbiome Innovation, Jacobs School of Engineering, University of California-San Diego, La Jolla, CA.
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
- Center for Infectious and Inflammatory Diseases, Institute of Biosciences and Technology, Texas A&M University, Houston, TX.
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
- Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX.
- Department of Pharmacology, School of Medicine, University of California-San Diego, La Jolla, CA.
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego, La Jolla, CA.
- Center for Microbiome Innovation, Jacobs School of Engineering, University of California-San Diego, La Jolla, CA.
- Department of Pharmacology, School of Medicine, University of California-San Diego, La Jolla, CA.
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego, La Jolla, CA.
- Center for Microbiome Innovation, Jacobs School of Engineering, University of California-San Diego, La Jolla, CA.
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