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Antigenic analysis of Rhodococcus equi preparations using different horse sera
A M Fontanals1, T Becú, G Polledo
1Immunology Unit, School of Veterinary Sciences, University of Buenos Aires, Argentina.
Veterinary Microbiology
|June 16, 1997
Summary
A novel Rhodococcus equi vaccine shows promise for preventing foal pneumonia by eliciting antibodies against multiple antigens, including altered virulence-associated protein A (VapA). Further analysis revealed high concentrations of immunogenic, higher molecular weight antigens contributing to vaccine efficacy.
Area of Science:
- Veterinary immunology
- Bacterial pathogenesis
- Vaccine development
Background:
- Rhodococcus equi causes significant pneumonia in foals.
- Existing vaccines aim to protect against R. equi infections.
- The role of specific antigens in vaccine-induced immunity requires further elucidation.
Purpose of the Study:
- To analyze the antigenic composition of a promising R. equi vaccine.
- To compare the vaccine's antigens with other R. equi preparations.
- To investigate the antibody response to vaccine antigens in horses.
Main Methods:
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting were used.
- Antigenic analysis was performed using various equine sera and antibodies.
- Vaccine and R. equi preparations (whole cell, VapA extract) were compared.
Main Results:
- The R. equi vaccine contained numerous high-concentration proteins, particularly in high molecular weight regions.
- Hyperimmune sera strongly recognized high molecular weight antigens and a low molecular weight zone (<14 kDa).
- While VapA was detected in an altered form, other higher molecular weight antigens were also immunogenic.
Conclusions:
- The vaccine induces antibodies against multiple R. equi antigens, not solely VapA.
- Higher molecular weight antigens, alongside VapA, likely contribute to protective immunity in foals.
- The vaccine's antigenic profile supports its potential efficacy against R. equi pneumonia.