The main objectives are as follows:
* To validate a specific serological test for the diagnostic and epidemiology of cowdriosis by the mean of an ELISA kit based on one part of the recombinant major antigenic protein 1 (MAP1).
* To establish a PCR assay for the detection and strain characterisation of Cowdria ruminantium (CR) in infected ruminants and in the vector Amblyomma variegatum.
* To assess in the field the efficacy of the vaccination method using adjuvated killed CR as opposed to the protection confered by attenuated strains and the method of infection and treatment.
* To understand the immunological responses leading to protection and to characterise immune effector cells for the search of potential protective antigens. To define antigens which may be used for epidemiological studies and vaccination assays.
* To find appropriate vectors for delivery of protective antigens: nacked DNA or recombinant capripox vectors.
With the outcome of more specific and sensitive tests to detect CR and antibodies to CR, comprehensive epidemiological surveys can be performed in countries were the impact of cowdriosis has not been fully appreciated. Field trials will assess the benefit of vaccination with new methods. Potential protective antigens can be pointed out to make a safe recombinant vaccine in an appropriate vector which will be an economical solution for this important tick-borne disease.
The key activities envisaged are:
* Analysis of a large sampling of sera from different African countries and the West Indies with the new ELISA kit for validation in different laboratories prior release.
* Genome analysis of CR in order to characterise stocks and strains of CR. Homologous variable regions will be identified by the use of RAPDs techniques and screening of CR libraries with RAPDs products. Sequence comparison of these regions will allow to derive stock-specific primers to set a PCR assay for the detection of CR in ruminants and ticks.
* Further epidemiological studies using ELISA and PCR assays will be conducted in geographical regions were the disease has been poorly identified previously (ie Burkina-Faso).
* Cellular immunological techniques will be used to identify T-cell populations responding to CR antigens. Derivation of T-cell lines will provide tools for selection of antigens for further immunological assays.
* Assessment of protective immunity by selected antigens in the mouse and ruminant models.
Antigens as recombinant proteins in adjuvant or as DNA cloned in eucaryotic expression vectors will be delivered to animals which will be further challenged with a lethal dosis of CR.
* Insertion of potential protective antigens into the attenuated capripox vector.
Funding SchemeCSC - Cost-sharing contracts
GU24 0NF Woking
EH25 9RG Roslin
3508 TD Utrecht