![[BioMatNet Database - FAIR Program]](../images/Fair.gif) |
Commercial Success of ECLAIR Programme
AGRE-0049: Improvement of brucellosis prevention, development of a vaccine and a serological test using different recombinant antigens to discriminate vaccinated from infected animals |
AGRE-0049: Improvement of brucellosis prevention, development of a vaccine and a serological test using different recombinant antigens to discriminate vaccinated from infected animals
Science Background
Brucellosis is one of the most important diseases in farm animals worldwide. Hence, the development of methods for control of this disease has been a priority within the European Union. For vaccination to be used effectively in the early stages of an eradication programme, it is important to be able to distinguish individuals that have been infected after vaccination and thus may be carriers of the disease and a potential source of infection to other animals.
Objectives
The main goal was to develop a vaccine that would allow discrimination between infected and vaccinated animals. This would be achieved by identification of Brucella protein antigens that were suitable for specific and sensitive diagnosis of Brucella infection in livestock animals and humans. Both humoral and cellular responses were to be considered for the development of diagnostic tools. The corresponding genes would then be identified and characterized. Large-scale production and purification of Brucella proteins, via expression in heterologous hosts, would be necessary to allow detailed study of the immune response towards these antigens and to develop a diagnostic assay based on these proteins. These antigens would then undergo serological analysis in order to select an appropriate combination for optimal detection of infected individuals. The protein antigens responsible for cell-mediated immunity and protection against Brucella infection would be studied in order to evaluate the effect of Brucella outer membrane proteins on the protective immune response. These results would be used to develop a vaccine that could be used in combination with the diagnostic assays to differentiate vaccinated from infected animals. It was proposed that an anti-idiotype approach would be used that would mimic protective epitopes defined by monoclonal antibodies directed towards the Brucella lipopolysaccharides. This would then be used to construct live vaccine strains, where genes encoding key diagnostic antigens were deleted.
Significant changes and results since end of ECLAIR
Patents were filed in 1995 and 1997. In-house research carried out by INRA and Innogenetics has resulted in the identification of improved candidate diagnostic antigens. Further study of these antigens is being funded under FAIR.
Results
At end of this ECLAIR project
This project showed that, in small ruminants, a limited number of Brucella protein antigens may be sufficient to detect all infected animals an that an indirect ELISA assay based on these antigens can compete with the classical serological tests. However, it was concluded that serology based on protein antigens was not feasible for cattle. Recombinant candidate protein components tested were not able to produce a delayed type hypersensitivity (DTH) reaction. In vitro interferon gamma assay using recombinant proteins could be used, but this required further evaluation. The role of outer membrane proteins (Omps) in protection against disease was not supported by vaccination experiments in the mouse model using major purified recombinant Brucella Omps. However, expression of the 25 kDa Omp in Escherichia coli in association with the bacterial cell did produce a preparation that could confer significant protection in the mouse model, suggesting that the presentation method used may be important for induction of protective response.
Tools were generated to construct deletion strains using double homologous recombination and the feasibility of this approach was proven by the isolation and characterization of Brucella strains, deleted in one specific gene. Evaluation of two strains, deleted in one specific gene, showed that residual virulence was not effected in the mouse model. It was concluded that the work provided the basis for a potential commercial product. However, further field trials would be necessary to validate the antigens for cellular or humoral diagnosis and to evaluate the protection conferred by the newly constructed strains in the target animals. Positive results could lead to the introduction onto the market of a vaccine coupled with a diagnostic assay that could be used to assist in the eradication of brucellosis in small ruminants.
Current position
Although the project generated a number of research tools, several man-years of research are needed to come to a potential product. INRA and Innogenetics continued the research in-house resulting in the identification of improved candidate diagnostic antigens by INRA. Research on the ECLAIR antigens was therefore abandoned. Funding has been obtained to study these new antigens under FAIR5-CT97-3360: Development of a genetically modified Brucella melitensis rev. 1 live vaccine and associated diagnostic assay allowing discrimination between vaccinated and infected sheep, however the research phase on the vaccine and diagnostic will not be completed until 2002.
Impact
Commercial
The research has not yet led to a commercial product. However, two patent applications have been filed on Brucella antigens: PCT/EP95/04670 (antigen 17 kDa) and PCT/EP97/04668 (antigen 39 kDa).
Associated
The main objective of the Immunology Laboratory of FUNDP, URBM (Belgium), a participant in this project, continues to be the study of the interaction of the bovine immune system and the two main pathogens of economic importance, Brucella and bovine respiratory syncitial virus (BRSV).
Contacts
Author
FUNDP
INRA
Innogenetics N.V.
© Copyright 2006 Policy Statements
Updated
by CPL Press:
03/07/2007
- biomatnet@biomatnet.org
 |
 |
 |
News |
 |
Events |
|
|