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Vaccination with a live multi-gene deletion strain protects horses against virulent challenge with Streptococcus equi

Lookup NU author(s): Dr Jeong-Jin Lee


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Strangles, caused by Streptococcus equi subspecies equi (S. equi) is one of the most frequently diagnosed infectious diseases of horses and there remains a significant need to develop new preventative vaccines. We generated a live vaccine strain of S. equi containing deletions in six genes: sagA, hasA, aroB, pyrC, seM and recA, which was administered to nine Welsh mountain ponies via the intramuscular route. Four vaccinated ponies developed adverse reactions following the first vaccination from which the live vaccine strain was isolated. Two of these ponies were withdrawn from the study and seven ponies received a second vaccination, one of which then developed an adverse reaction. Nine control ponies injected with culture media alone developed no adverse reactions. Following challenge with a virulent strain of S. equi, none of the seven vaccinated ponies had developed clinical signs of strangles eleven days post-challenge, compared to six of nine control ponies over the same period (P= 0.0114). A lymph node abscess was identified in one of the seven vaccinated ponies at post-mortem examination, whilst all nine control ponies had at least one lymph node abscess (P =0.0009). Three of the six vaccinated ponies that were protected from strangles had not developed an adverse reaction following vaccination, suggesting that a better understanding of the pro-inflammatory responses to S. equi could lead to the development of a live attenuated vaccine against strangles that is safe for administration via intramuscular injection. (C) 2015 Elsevier Ltd. All rights reserved.

Publication metadata

Author(s): Robinson C, Heather Z, Slater J, Potts N, Steward KF, Maskell DJ, Fontaine MC, Lee JJ, Smith K, Waller AS

Publication type: Article

Publication status: Published

Journal: Vaccine

Year: 2015

Volume: 33

Issue: 9

Pages: 1160-1167

Print publication date: 25/02/2015

Online publication date: 15/01/2015

Acceptance date: 06/01/2015

ISSN (print): 0264-410X

ISSN (electronic): 1873-2518

Publisher: Elsevier


DOI: 10.1016/j.vaccine.2015.01.019


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vet/prj/734Horserace Betting Levy Board