Virulence-associated protein-specific serum immunoglobulin G-isotype expression in young foals protected against Rhodococcus equi pneumonia by oral immunization with virulent R. equi.
Abstract: The purpose of this study was to determine whether foals immunized orally from 2 days of age with virulent Rhodococcus equi developed a protective pulmonary immune response and to characterise the antibody response of the immunized foals to the virulence-associated proteins (Vaps) of the bacterium. Two groups of foals were used. One (n=4) was given live R. equi ATCC 33701 orally at 2, 7, and 14 days of age. The second group comprised three non-immunized foals age-matched to the vaccinates. At 3 weeks of age, 1 week after the final immunization, both groups were challenged intrabronchially with virulent R. equi ATCC 33701 and observed for 2 weeks post-challenge. Unvaccinated foals became clinically pneumonic and had high fever with increased heart and respiratory rates and severe pneumonia evident at necropsy. Foals of the immunized group remained healthy and lung lesions were not found post-mortem. Thus, it is possible to immunize young foals orally to protect them by 3 weeks of age against lung challenge with R. equi, even in the presence of maternal antibodies. The antibody response of the immunized foals confirmed that VapA and VapC are highly immunogenic. The immunoglobulin G isotype-related serum antibody response of immunized compared to non-immunized foals had an IgGT bias and a relatively low IgGa:IgGb ratio, both features different from what has been previously observed in immune adults and immune foals. This suggests that the serum IgG isotype profile of antibody cannot be used as a measure of evidence of protection against R. equi pneumonia.
Publication Date: 2005-08-09 PubMed ID: 16112256DOI: 10.1016/j.vaccine.2005.07.050Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research is about investigating if young foals can develop a protective immune response against Rhodococcus equi pneumonia through oral immunization. The study also aimed to characterize how the immunized foals respond to the virulence-associated proteins (Vaps) of the bacterium.
Methodology
- Two groups of foals participated in the study – one group (n=4) received live R. equi orally at 2, 7, and 14 days of age, and the other consisted of three non-immunized foals matched in age to the vaccinated group.
- At 3 weeks old, a week after the final immunization, the foals were exposed to virulent R. equi through intrabronchial challenge and monitored for 2 weeks post-challenge.
Results
- The unvaccinated foals became clinically pneumonic, with symptoms including high fever, increased heart and breathing rates, and severe pneumonia evident at necropsy.
- In contrast, the foals from the immunized group remained healthy, and post-mortem examinations revealed no lung lesions.
Conclusions
- The results appear to show that it’s possible to immunize young foals orally to protect them against lung challenge with R. equi by three weeks of age, even if maternal antibodies are present.
- The antibody response of the immunized foals against VapA and VapC, two of the bacterium’s virulence-associated proteins, was strong, confirming their high immunogenicity.
- However, the immunoglobulin G isotype-related serum antibody response of immunized foals was found to have a bias towards IgGT and a relatively low IgGa:IgGb ratio, contradicting previous observations in immune adults and immune foals. Therefore, the research concludes that the serum IgG isotype profile of the antibody cannot be used as a measure of protection against R. equi pneumonia.
Cite This Article
APA
Hooper-McGrevy KE, Wilkie BN, Prescott JF.
(2005).
Virulence-associated protein-specific serum immunoglobulin G-isotype expression in young foals protected against Rhodococcus equi pneumonia by oral immunization with virulent R. equi.
Vaccine, 23(50), 5760-5767.
https://doi.org/10.1016/j.vaccine.2005.07.050 Publication
Researcher Affiliations
- Department of Pathobiology, University of Guelph, Guelph, Ont., Canada.
MeSH Terms
- Administration, Oral
- Animals
- Antibodies, Bacterial / blood
- Antibodies, Bacterial / immunology
- Bacterial Vaccines / immunology
- Horses
- Immunization
- Immunoglobulin G / immunology
- Immunoglobulin Isotypes / immunology
- Pneumonia, Bacterial / immunology
- Pneumonia, Bacterial / prevention & control
- Pneumonia, Bacterial / veterinary
- Rhodococcus equi / immunology
- Rhodococcus equi / pathogenicity
- Virulence
- Virulence Factors / immunology
Citations
This article has been cited 18 times.- Golen GS, Erganiş O, Balevi A. Comparison of the efficacies of Rhodococcus equi recombinant vaccine in mice. Vet Res Forum 2025;16(5):253-259.
- da Silveira BP, Kahn SK, Legere RM, Bray JM, Cole-Pfeiffer HM, Golding MC, Cohen ND, Bordin AI. Enteral immunization with live bacteria reprograms innate immune cells and protects neonatal foals from pneumonia. Sci Rep 2025 May 25;15(1):18156.
- da Silveira BP, Cohen ND, Lawhon SD, Watson RO, Bordin AI. Protective immune response against Rhodococcus equi: An innate immunity-focused review. Equine Vet J 2025 May;57(3):563-586.
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- Knox A, Zerna G, Beddoe T. Current and Future Advances in the Detection and Surveillance of Biosecurity-Relevant Equine Bacterial Diseases Using Loop-Mediated Isothermal Amplification (LAMP). Animals (Basel) 2023 Aug 18;13(16).
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- Rocha JN, Cohen ND, Bordin AI, Brake CN, Giguère S, Coleman MC, Alaniz RC, Lawhon SD, Mwangi W, Pillai SD. Oral Administration of Electron-Beam Inactivated Rhodococcus equi Failed to Protect Foals against Intrabronchial Infection with Live, Virulent R. equi. PLoS One 2016;11(2):e0148111.
- Okoko T, Blagova EV, Whittingham JL, Dover LG, Wilkinson AJ. Structural characterisation of the virulence-associated protein VapG from the horse pathogen Rhodococcus equi. Vet Microbiol 2015 Aug 31;179(1-2):42-52.
- Bordin AI, Pillai SD, Brake C, Bagley KB, Bourquin JR, Coleman M, Oliveira FN, Mwangi W, McMurray DN, Love CC, Felippe MJ, Cohen ND. Immunogenicity of an electron beam inactivated Rhodococcus equi vaccine in neonatal foals. PLoS One 2014;9(8):e105367.
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- Lohmann KL, Lopez AM, Manning ST, Marques FJ, Brownlie R, Allen AL, Sangster AE, Mutwiri G, Gerdts V, Potter A, Townsend HG. Failure of a VapA/CpG oligodeoxynucleotide vaccine to protect foals against experimental Rhocococcus equi pneumonia despite induction of VapA-specific antibody and interferon-γ response. Can J Vet Res 2013 Jul;77(3):161-9.
- Bordin AI, Suchodolski JS, Markel ME, Weaver KB, Steiner JM, Dowd SE, Pillai S, Cohen ND. Effects of administration of live or inactivated virulent Rhodococccus equi and age on the fecal microbiome of neonatal foals. PLoS One 2013;8(6):e66640.
- van der Geize R, Grommen AW, Hessels GI, Jacobs AA, Dijkhuizen L. The steroid catabolic pathway of the intracellular pathogen Rhodococcus equi is important for pathogenesis and a target for vaccine development. PLoS Pathog 2011 Aug;7(8):e1002181.
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- Harris SP, Fujiwara N, Mealey RH, Alperin DC, Naka T, Goda R, Hines SA. Identification of Rhodococcus equi lipids recognized by host cytotoxic T lymphocytes. Microbiology (Reading) 2010 Jun;156(Pt 6):1836-1847.
- Jacks S, Giguère S, Crawford PC, Castleman WL. Experimental infection of neonatal foals with Rhodococcus equi triggers adult-like gamma interferon induction. Clin Vaccine Immunol 2007 Jun;14(6):669-77.
- Jacks S, Giguère S, Prescott JF. In vivo expression of and cell-mediated immune responses to the plasmid-encoded virulence-associated proteins of Rhodococcus equi in foals. Clin Vaccine Immunol 2007 Apr;14(4):369-74.
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