Immune response to vaccines based upon the VapA protein of the horse pathogen, Rhodococcus equi, in a murine model.
Abstract: Rhodococcus equi is a significant pathogen in foals predominantly causing a pyogranulomatous bronchopneumonia. Many vaccine candidates have been tested for the prevention of R. equi disease in foals. However, none of these have been developed for widespread commercial use. Previous studies have shown that a Th1 immune response is imperative for the protection of foals against R. equi disease. In this study a DNA and a protein vaccine based upon the well-characterised R. equi virulence-associated protein VapA were developed. The vaccines were tested in the BALB/c murine model and the results showed that both vaccine candidates elicited a Th1-type response in the host. Upon coadministration of an IL-12 expression plasmid with the DNA vaccine, an increase in the Th1 response was observed. However, when mice were challenged with 1.5 x 10(7) virulent R. equi ATCC 33701 none of the vaccinated mice showed protection apart from the mice immunised with live R. equi. These results indicate that despite their immunogenicity the VapA-based DNA and recombinant protein vaccines developed in this study were unable to prevent bacterial replication following a high-dose systemic challenge with virulent R. equi in the BALB/c model.
Publication Date: 2005-02-18 PubMed ID: 15715172DOI: 10.1016/j.ijmm.2004.09.011Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research investigates potential vaccines for the horse pathogen Rhodococcus equi, which causes a type of pneumonia in foals, based on the pathogen’s VapA protein. While both a DNA and a protein vaccine elicit the desired immune response in mice, neither provided protection when the mice were exposed to.
Background
- The study sought to develop potential vaccines to counteract Rhodococcus equi, a pathogen that causes pyogranulomatous bronchopneumonia, a severe lung infection in foals.
- This pathogen is a significant problem in the equine industry and despite several efforts, no commercial vaccines are currently available to prevent this disease.
- Prior research indicates that a Th1 immune response, a type of immune system reaction, is crucial for protection against R. equi disease.
Vaccines Based on VapA Protein
- The researchers developed two kinds of experimental vaccines centered on VapA, a protein associated with R. equi virulence.
- The vaccines were a DNA vaccine and a recombinant protein vaccine, both designed to elicit the desired Th1 immune response.
Testing and Results
- The vaccines were tested on the BALB/c mouse model, a common laboratory mouse strain used in scientific research.
- The results indicated that both experimental vaccines succeed in eliciting a Th1-type immune response.
- When researchers supplemented the DNA vaccine with an IL-12 expression plasmid, they observed an increased Th1 response.
Efficacy and Protection
- However, when these vaccinated mice were exposed to a high dose of the virulent strain of R. equi, none exhibited protection, except for the group that received a live R. equi vaccine.
- This implies that while these experimental vaccines stimulated the desired immune response, they were not effective in preventing bacterial replication after exposure to a high-dose, suggesting they may not be effective in preventing the disease.
Conclusion
- The VapA-based DNA and recombinant protein vaccines, while provoking a proper immune response, failed to provide adequate protection in the mouse model.
- The findings in this study underscore the challenges in developing an effective vaccine against R. equi and the need for further research.
Cite This Article
APA
Vanniasinkam T, Barton MD, Heuzenroeder MW.
(2005).
Immune response to vaccines based upon the VapA protein of the horse pathogen, Rhodococcus equi, in a murine model.
Int J Med Microbiol, 294(7), 437-445.
https://doi.org/10.1016/j.ijmm.2004.09.011 Publication
Researcher Affiliations
- Infectious Diseases Laboratories, Institute of Medical and Veterinary Science, P.O. Box 14, Rundle Mall, Adelaide, SA 5000, Australia.
MeSH Terms
- Actinomycetales Infections / immunology
- Actinomycetales Infections / prevention & control
- Animals
- Antibodies, Bacterial / blood
- Bacterial Proteins / genetics
- Bacterial Proteins / immunology
- Bacterial Vaccines / administration & dosage
- Bacterial Vaccines / genetics
- Bacterial Vaccines / immunology
- COS Cells
- Horse Diseases / immunology
- Horse Diseases / prevention & control
- Horses
- Mice
- Mice, Inbred BALB C
- Recombinant Proteins / genetics
- Recombinant Proteins / immunology
- Rhodococcus equi / immunology
- Rhodococcus equi / pathogenicity
- Th1 Cells / immunology
- Vaccines, DNA / administration & dosage
- Vaccines, DNA / immunology
- Virulence Factors / genetics
- Virulence Factors / immunology
Citations
This article has been cited 2 times.- Giles C, Ndi O, Barton MD, Vanniasinkam T. An Adenoviral Vector Based Vaccine for Rhodococcus equi.. PLoS One 2016;11(3):e0152149.
- Dhama K, Mahendran M, Gupta PK, Rai A. DNA vaccines and their applications in veterinary practice: current perspectives.. Vet Res Commun 2008 Jun;32(5):341-56.
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