Intramuscular vaccination with Strangvac is safe and induces protection against equine strangles caused by Streptococcus equi.
Abstract: The equine disease strangles, caused by Streptococcus equi, remains a major cause of welfare and economic cost to the global horse industry. Here we report the safety, immunogenicity and efficacy of a novel multi-component chimeric fusion protein vaccine, called Strangvac, when administered to ponies via the intramuscular route. Across the four studies, Strangvac was safe and induced robust antibody responses towards the vaccine components in blood serum and the nasopharynx, which were boosted by revaccination up to 12 months after a primary course of 2 vaccinations 4 weeks apart. The vaccine response did not cross-react with a commercial strangles iELISA, which identifies horses that have been exposed to S. equi, demonstrating that it was possible to differentiate infected from vaccinated animals (DIVA). Following challenge with S. equi strain 4047 (Se4047), all 36 control ponies that had received an adjuvant-only placebo vaccine developed clinical signs of strangles. In contrast, intramuscular vaccination with Strangvac protected ponies significantly from challenge with Se4047 at two weeks (5 of 16 ponies protected (31%), P = 0.04) and two months (7 of 12 ponies protected (58%), P = 0.0046 (including pooled control data) after second vaccination. Optimal protection (15 of 16 ponies protected (94%), P < 0.0001) was observed following challenge at two weeks post-third vaccination. Our data demonstrate that Strangvac is safe, has DIVA capability and provides a rapid onset of protective immunity against strangles. We conclude that Strangvac is a valuable tool with which to protect horses from strangles, particularly during high-risk periods, whilst maintaining the mobility of horse populations as required by the global equine industry.
Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.
Publication Date: 2020-06-02 PubMed ID: 32507408DOI: 10.1016/j.vaccine.2020.05.046Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article investigates the safety, immunogenicity, and effectiveness of a novel horse vaccine called Strangvac against the equine disease strangles, which is inflicted by the bacteria Streptococcus equi.
Safety and Immunogenicity of Strangvac
- The team conducted a series of four studies which tested Strangvac’s safety and induced antibody responses. Strangvac injection into horses was found safe and initiated strong antibody response towards the components of the vaccine.
- These antibodies were found in blood serum and the nasopharynx and their production could be boosted by revaccinating the ponies for up to 12 months after an initial course of two vaccines Administered 4 weeks apart.
- This indicates Strangvac is safe for horses and successfully stimulates the immune system to fight against the bacteria causing strangles.
Discrimination between Vaccinated and Infected Horses
- The horse’s response to the Strangvac vaccine did not cross-react with a commercial strangles called iELISA, which identifies horses that have been previously exposed to S. equi.
- Thus demonstrating it was possible to differentiate vaccinated horses from infected ones, an attribute known as DIVA (Differentiating Infected from Vaccinated Animals).
- This is crucial in preventing needless culls and ensuring that only infected animals are treated, thus curtailing the potential spread of the disease.
Efficacy of Strangvac Against Strangles
- The effectiveness of Strangvac was assessed through a controlled infection using S. equi strain 4047. All 36 ponies that were given a placebo, instead of the vaccine, developed clinical signs of strangles.
- In contrast, ponies that were administered Strangvac were significantly protected from the same strain. Two weeks after the second vaccination, 31% of the ponies were protected, and after two months, the protection rate increased to 58%.
- Optimal protection of 94% was observed only two weeks after the third vaccine dosage. This implies that a prime-boost vaccination regime could potentially offer extensive protection against strangles.
Conclusions of the Study
- The research thus concludes that Strangvac is a safe and effective vaccine against strangles in horses, providing quick onset of immunity.
- Its DIVA capacity allows differentiation between vaccinated and infected horses, making it a valuable asset, particularly during high-risk periods.
- This would enable the continuous mobility required by the global horse industry while minimizing the chances of disease outbreaks.
Cite This Article
APA
Robinson C, Waller AS, Frykberg L, Flock M, Zachrisson O, Guss B, Flock JI.
(2020).
Intramuscular vaccination with Strangvac is safe and induces protection against equine strangles caused by Streptococcus equi.
Vaccine, 38(31), 4861-4868.
https://doi.org/10.1016/j.vaccine.2020.05.046 Publication
Researcher Affiliations
- Department of Bacteriology, Animal Health Trust, Lanwades Park, Kentford, Newmarket, CB8 7UU, United Kingdom.
- Department of Bacteriology, Animal Health Trust, Lanwades Park, Kentford, Newmarket, CB8 7UU, United Kingdom.
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7036, SE-750 07 Uppsala, Sweden.
- Department of Microbiology, Tumour and Cellbiology, Karolinska Institutet, P.O. Box 280, SE-171 77 Stockholm, Sweden.
- Intervacc AB, P.O. Box 112, SE-129 22 Hӓgersten, Sweden.
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7036, SE-750 07 Uppsala, Sweden.
- Department of Microbiology, Tumour and Cellbiology, Karolinska Institutet, P.O. Box 280, SE-171 77 Stockholm, Sweden; Intervacc AB, P.O. Box 112, SE-129 22 Hӓgersten, Sweden. Electronic address: jan-ingmar.flock@intervacc.com.
MeSH Terms
- Animals
- Horse Diseases / prevention & control
- Horses
- Lymphadenitis
- Streptococcal Infections / prevention & control
- Streptococcal Infections / veterinary
- Streptococcus equi
- Vaccination
Conflict of Interest Statement
Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: This work was sponsored by Intervacc AB and clinical trials were conducted at Animal Health Trust. J-IF has a current employment at Intervacc and OZ a previous employment. The following authors are stakeholders of Intervacc AB: J-IF, MF, OZ, BG and LF.
Citations
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