{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T23:28:05Z","timestamp":1788564485643,"version":"build-2803163510"},"reference-count":30,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2025,10,17]],"date-time":"2025-10-17T00:00:00Z","timestamp":1760659200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Intervacc AB"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Background:\u00a0Streptococcus equi subspecies equi (S. equi) is the cause of strangles, one of the most prevalent diseases of horses worldwide. The disease is characterised by fever and the formation of abscesses in the lymph nodes of the head and neck, which can restrict the airway. A multicomponent subunit vaccine, Strangvac, has been shown to effectively reduce clinical signs of strangles and to reduce its incidence. Objective: The aim of this study was to determine the immune response against the immunoglobulin-cleaving endopeptidase IdeE, a key protective component within the vaccine and the ability of antibodies to neutralize the proteolytic activity of IdeE. Methods: An in vitro assay was developed to measure the functional inhibition of recombinant IdeE by horse sera pre- and post-vaccination. The IdeE-neutralising titres were compared to the corresponding IdeE-specific antibody titres measured by iELISA (indirect Enzyme-Linked Immunosorbent Assay). Results: A significant IdeE-specific antibody response in blood serum collected from ponies was induced after Strangvac vaccinations. Concomitantly, significant increases in the neutralising activity of IdeE occurred, persisting for at least 12 months post-second vaccination. IdeE-neutralising activity was further increased significantly after a third vaccination, even when the third dose was administered 12 months after the second dose, demonstrating that immunological memory to the vaccine persisted for 12 months. There was a significant correlation between the IdeE-neutralising activity of blood sera and the level of IdeE-specific antibodies. Conclusions: These data provide insights into one potential mechanism by which this vaccine protects Equids against or during S. equi infection.<\/jats:p>","DOI":"10.3390\/vaccines13101061","type":"journal-article","created":{"date-parts":[[2025,10,17]],"date-time":"2025-10-17T07:33:50Z","timestamp":1760686430000},"page":"1061","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Neutralisation of the Immunoglobulin-Cleaving Activity of Streptococcus equi Subspecies equi IdeE by Blood Sera from Ponies Vaccinated with a Multicomponent Protein Vaccine"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4903-2321","authenticated-orcid":false,"given":"Francesco","family":"Righetti","sequence":"first","affiliation":[{"name":"Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6660-7233","authenticated-orcid":false,"given":"Karina","family":"Hentrich","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden"},{"name":"Clinical Microbiology, Karolinska University Hospital, 171 76 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Margareta","family":"Flock","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4080-5183","authenticated-orcid":false,"given":"Sara","family":"Frosth","sequence":"additional","affiliation":[{"name":"Department of Biomedical Science and Veterinary Public Health, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9410-6820","authenticated-orcid":false,"given":"Karin","family":"Jacobsson","sequence":"additional","affiliation":[{"name":"Department of Biomedical Science and Veterinary Public Health, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0335-8529","authenticated-orcid":false,"given":"Joakim","family":"Bjerketorp","sequence":"additional","affiliation":[{"name":"Department of Biomedical Science and Veterinary Public Health, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anuj","family":"Pathak","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Noela","family":"Ido","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5429-4759","authenticated-orcid":false,"given":"Birgitta","family":"Henriques-Normark","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden"},{"name":"Clinical Microbiology, Karolinska University Hospital, 171 76 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lars","family":"Frykberg","sequence":"additional","affiliation":[{"name":"Department of Biomedical Science and Veterinary Public Health, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3081-2037","authenticated-orcid":false,"given":"Romain","family":"Paillot","sequence":"additional","affiliation":[{"name":"Intervacc AB, 129 22 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7044-0701","authenticated-orcid":false,"given":"Bengt","family":"Guss","sequence":"additional","affiliation":[{"name":"Department of Biomedical Science and Veterinary Public Health, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tim","family":"Wood","sequence":"additional","affiliation":[{"name":"Intervacc AB, 129 22 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jan-Ingmar","family":"Flock","sequence":"additional","affiliation":[{"name":"Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7111-9549","authenticated-orcid":false,"given":"Andrew Stephen","family":"Waller","sequence":"additional","affiliation":[{"name":"Department of Biomedical Science and Veterinary Public Health, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden"},{"name":"Intervacc AB, 129 22 Stockholm, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"633","DOI":"10.1111\/jvim.15043","article-title":"Streptococcus equi Infections in Horses: Guidelines for Treatment, Control, and Prevention of Strangles-Revised Consensus Statement","volume":"32","author":"Boyle","year":"2018","journal-title":"J. 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