VapA-specific IgG and IgG subclasses responses after natural infection and experimental challenge of foals with Rhodococcus equi.
Abstract: Rhodococcus equi is a common cause of pneumonia in young foals worldwide and has considerable economic effects on the global equine industry. Despite ongoing efforts, no vaccine is currently available to prevent rhodococaal pneumonia. This is due, in part, to an incomplete understanding of the protective immune response to this bacterium. While antibodies to VapA, a lipoprotein produced by virulent R. equi, are useful in differentiating antibody production in response to pathogenic versus non-pathogenic strains, the significance of the humoral response of foals to this lipoprotein remains poorly defined. The objectives of this study were to evaluate changes in VapA-specific IgG and IgG subclasses after exposure and infection of neonatal foals. Experimental foals included those challenged with R. equi at 1 (n=18), 2 (n=4) and 3 (n=6) weeks of age. Confirmed naturally infected (n=7) and not infected (n=3) foals were also included. All foals were bled 24h after birth and weekly thereafter for a period of 8 weeks. Antibody changes over time were evaluated. Following birth, VapA-specific IgGs significantly (p<0.05) decreased over time in all foals as a result of normal decay of passively transferred antibodies. Both VapA-specific IgGa and IgG(T) significantly increased (p<0.05) after experimental challenge, however, the rise in IgG(T) occurred earlier. Only a significant (p<0.05) increase in VapA-specific IgG(T) over time was seen after natural infection. Whether VapA-specific IgG(T) can be used to differentiate rhodococcal from other pneumonias requires further investigation under field conditions.
Copyright © 2015 Elsevier B.V. All rights reserved.
Publication Date: 2015-01-18 PubMed ID: 25681111DOI: 10.1016/j.vetimm.2015.01.004Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research investigates the response of particular antibodies, known as VapA-specific IgG and its subclasses, following the infection and exposure of young horses, called foals, with a bacterium named Rhodococcus equi. This bacterium is a frequent cause of pneumonia in young foals and the research aims to enhance understanding of the immune response to potentially help develop a vaccine.
Study Motivation
- The study was conducted owing to the global economic impacts of Rhodococcal pneumonia in foals, caused by the Rhodococcus equi bacteria.
- At present, there is no vaccine available due to a lack of full understanding of the immune response to this bacterium.
- To develop such a preventive measure, it is important to understand the response of VapA-specific IgG and IgG subclasses, antibodies that respond to an lipoprotein – VapA – produced by potent strains of the bacteria.
Research Approach
- The study aimed to evaluate VapA-specific IgG and its subclasses’ responses by exposing neonatal foals to Rhodococcus equi.
- Different age groups of foals, specifically those of 1, 2, and 3-week-old were experimentally challenged with the pathogen.
- The study also included naturally infected and non-infected foals for comparison.
- Blood samples were collected 24 hours post-birth and then on a weekly basis for a period of 8 weeks.
- The variations in antibodies over time were assessed.
Findings
- Right after the birth, there was a significant decrease in VapA-specific IgGs in all foals due to the standard decay of antibodies transferred passively.
- Following the experimental challenge, a notable increase was observed in both variations of VapA-specific IgG subclasses.
- However, the rise in IgG(T), another subclass of VapA-specific IgG, was noticed earlier.
- Only a significant increase in VapA-specific IgG(T) was observed after natural infection.
Future Considerations
- The research suggests that VapA-specific IgG(T) may have potential as a diagnostic marker to differentiate rhodococcal pneumonia from other types.
- However, this hypothesis requires further investigations under real world, or ‘field’, conditions.
Cite This Article
APA
Sanz MG, Villarino N, Ferreira-Oliveira A, Horohov DW.
(2015).
VapA-specific IgG and IgG subclasses responses after natural infection and experimental challenge of foals with Rhodococcus equi.
Vet Immunol Immunopathol, 164(1-2), 10-15.
https://doi.org/10.1016/j.vetimm.2015.01.004 Publication
Researcher Affiliations
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, Kentucky,Lexington, KY 40546-009, United States.
- Washington State University, College of Veterinary Medicine, Pullman, WA 99164-6610, United States.
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, Kentucky,Lexington, KY 40546-009, United States.
- Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, Kentucky,Lexington, KY 40546-009, United States. Electronic address: dwhoro2@uky.edu.
MeSH Terms
- Actinomycetales Infections / immunology
- Actinomycetales Infections / prevention & control
- Actinomycetales Infections / veterinary
- Animals
- Animals, Newborn
- Antibodies, Bacterial / blood
- Antibodies, Bacterial / classification
- Antibody Specificity
- Bacterial Proteins / genetics
- Bacterial Proteins / immunology
- Horse Diseases / immunology
- Horse Diseases / microbiology
- Horse Diseases / prevention & control
- Horses
- Immunity, Humoral
- Immunoglobulin G / blood
- Immunoglobulin G / classification
- Recombinant Proteins / genetics
- Recombinant Proteins / immunology
- Rhodococcus equi / genetics
- Rhodococcus equi / immunology
- Rhodococcus equi / pathogenicity
- Virulence / immunology
Citations
This article has been cited 2 times.- Kalinowski M, Grądzki Z, Jarosz Ł, Adaszek Ł. Molecular analysis of the chromosomal 16S rRNA gene and vapA plasmid gene of Polish field strains of R. equi.. PLoS One 2018;13(9):e0204024.
- 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.
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