Elsevier

Research in Veterinary Science

Volume 138, September 2021, Pages 100-108
Research in Veterinary Science

Enhanced immune effects and protection conferred by simultaneously targeting GAPDH, SeM, and EAG of S. equi via TLR4

https://doi.org/10.1016/j.rvsc.2021.06.001Get rights and content

Highlights

  • •

    Optimized multivalent vacine against strangles provide evident high protection efficacy.

  • •

    SeM, EAG and GAPDH immunization elicit high expression level of Toll-like receptor (TLR)-4.

  • •

    SeM, EAG and GAPDH vaccination induce incrased major histocompatibility complex I(MHC-I), and T-cell receptor (TCR).

  • •

    SeM, EAG and GAPDH immunization increased the specific serum antibody level.

Abstract

Strangles, which is caused by Streptococcus equi subspecies equi, is one of the most prevalent equine infectious diseases and poses heavy economic losses worldwide. Although various vaccines have been used for decades, they seemed to be sub-optimal to demonstrate effective protection, and the antigen component of vaccines against S. equi remains to be optimized. In the present study, three target antigens (M-like protein, α2-macroglobulin and IgG-binding protein, and glyceraldehyde-3-phosphate dehydrogenase) were selected and expressed. Mice were immunized and challenged, and their immune response and efficacy were evaluated. The results revealed that this optimized multi-antigen treatment elicited a high expression level of T-cell receptor, major histocompatibility complex I, toll-like receptor TLR-4, and increased specific antibody. In addition, the challenge experiment showed an evidently improved protection efficacy. The present work demonstrated that these three proteins might be used as a promising multicomponent subunit vaccine candidate against S. equi infection.

Section snippets

Background

S. equi of Lancefield group C infection causes strangles predominantly in horses . Strangles is highly contagious and infects the upper respiratory tract and adjacent lymph nodes of horses (Harrington et al., 2002), and this condition is characterized by fever, lymph node swelling, abscess formation, and nasal discharge (Sweeney et al., 2005). Strangles is prevalent worldwide and causes severe economic consequences (Timoney, 2004; Jacobs et al., 2000).

To date, a variety of strategies have been

Ethics statement

BALB/c mice aged 6–8 weeks were obtained from the animal experimental center of Xinjiang Medical University, Urumqi, Xinjiang, China. Animal experiments were conducted following the guidelines of the Animal Ethics Committee, Xinjiang Agricultural University, China. The protocols used for these animal studies were approved by the Committee on Care and Use of Laboratory Animals of Xinjiang Agricultural University (Urumqi, Xinjiang, China; Protocol Permit Number: 2108002). All animal experiments

Expression of recombinant EAG, SeM, and GAPDH in E. coli

Transformed E. coli BL21 (DE3) strains harboring constructs pET-28a-EAG, pGEX-SeM, and pET-28a-GAPDH were incubated with IPTG to induce the expressions of the three target proteins. The recombinant EAG (rEAG), SeM (rSeM), and GAPDH (rGAPDH) of S. equi resulted in protein migration on SDS-PAGE with a molecular mass of 24, 64, and 30 kDa, respectively (Fig. 1A, B, and C).

Antibody response to vaccination with EAG, SeM, and GAPDH proteins

Mouse serum was collected on days 0, 14, 35, and 45, and the specific humoral immune response induced by immunization with EAG,

Discussion

Strangles is currently considered the most often diagnosed equine infectious disease worldwide (Waller et al., 2007); its incidence is highly significant in areas with large concentrations of horses. The disease has a low mortality rate but results in high morbidity, which is associated with economic losses to the equine industry (Libardoni et al., 2013). The development of effective preventative vaccines against strangles is the most reliable way to reduce the global disease burden, although

Conclusions

Many studies have been conducted to identify suitable antigen components for the development of multivalent strangles vaccine. Herein, we reported the immunization of a murine infection model with three antigens EAG, SeM, and GAPDH that elicited significantly increased specific serum antibodies and expression levels of TCR, MHC-I, and TLR-4 compared with the control. In addition, challenge experiments showed an evidently improved protection efficacy and a significant reduction in the bacterial

Funding

This work was supported by the National Natural Science Foundation of China (grants number U1803108 and 31660707).

Ethics approval and consent to participate

This study was conducted following the guidelines of the Animal Ethics Committee, Xinjiang Agricultural University, China. The protocols used for these animal studies were approved by the Committee on Care and Use of Laboratory Animals of Xinjiang Agricultural University (Urumqi, Xinjiang, China; Protocol Permit Number: 2108002).

Declaration of Competing Interest

All authors declare that they have no competing interest that relevant to the present manuscript.

References (45)

  • J.L. Livengood et al.

    Detection and differentiation of wild-type and a vaccine strain of Streptococcus equi ssp. equi using pyrosequencing

    Vaccine

    (2016)
  • C. Robinson et al.

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

    Vaccine

    (2015)
  • C. Robinson et al.

    Strangvac: recombinant fusion protein vaccine that protects against strangles, caused by Streptococcus equi

    Vaccine

    (2018)
  • C. Robinson et al.

    Intramuscular vaccination with Strangvac is safe and induces protection against equine strangles caused by Streptococcus equi

    Vaccine

    (2020)
  • M.A. Rodrigues et al.

    Development of a novel mucosal vaccine against strangles by supercritical enhanced atomization spray-drying of Streptococcus equi extracts and evaluation in a mouse model

    Eur. J. Pharm. Biopharm.

    (2012)
  • A.S. Sheoran et al.

    Nasal mucosal immunogenicity for the horse of a SeM peptide of Streptococcus equi genetically coupled to cholera toxin

    Vaccine

    (2002)
  • X. Sun et al.

    Subcutaneous immunization with Streptococcus pneumoniae GAPDH confers effective protection in mice via TLR2 and TLR4

    Mol. Immunol.

    (2017)
  • F.J. Wallace et al.

    An assessment of mucosal immunisation in protection against Streptococcus equi (Strangles) infections in horses

    Vet. Immunol. Immunopathol

    (1995)
  • A.S. Waller

    New perspectives for the diagnosis, control, treatment, and prevention of strangles in horses

    Vet. Clin. N. Am. Equine Pract.

    (2014)
  • A. Waller et al.

    Vaccination of horses against strangles using recombinant antigens from Streptococcus equi

    Vaccine

    (2007)
  • S. Bergmann et al.

    Glyceraldehyde-3-phosphate dehydrogenase of Streptococcus pneumoniae is a surface-displayed plasminogen-binding protein

    Infect. Immun.

    (2004)
  • G. Boel et al.

    Inhibition of cell surface export of group A streptococcal anchorless surface dehydrogenase affects bacterial adherence and antiphagocytic properties

    Infect. Immun.

    (2005)

    • Cited by (0)

    1

    Equal contributors.

    View full text
    © 2021 Elsevier Ltd. All rights reserved.