On the path to a vaccine for trypanosomosis
AAT, also known as nagana, causes serious losses in livestock from anaemia, loss of condition and emaciation. The livestock disease is found mainly in areas of Africa where its vector, the tsetse fly, exists. A European-funded project, 'Development of an "anti-disease" vaccine and diagnostic tests for African trypanosomosis' (TRYPADVAC2) continued earlier work to develop a vaccine to prevent the disease. As well as preventive measures, project objectives included the development of methods for accurate diagnosis. By developing immunisation strategies against pathogenic factors, TRYPADVAC2 took an anti-disease vaccine approach. The team expanded on previous work involving an immumosuppressive cysteine protease of Trypanosoma congolense, so-called congopain. They also focused on screening and characterisation of other pathogenic molecules, particularly those causing anaemia and host fat and energy metabolism disturbances. Genomics and proteomics were used to investigate parasite pathogenic pathways. TRYPADVAC2 used crystallisation studies to determine the 3D structure of congopain as a basis for vaccine studies. In addition, other molecules with potential for diagnostic and therapeutic roles were identified. These included the cathepsin B coding genes, metacaspases found in plants, fungi and protozoa but not in mammals – natural inhibitors of trypanosomal proteases. Antibody and antigen detection tests based on previously identified molecules as well as some new discoveries from four species of Trypanosoma and different mammal hosts proved very fruitful. Nineteen recombinant and three native antigens were identified, isolated from natural and experimental infections. On the diagnostic front, a large number of antigens were tested. One, cathepsin B, gave very promising results for a test for T. congolense, the main cause of nagana in farmed animals. The TRYPADVAC2 project generated almost 20 scientific papers on trypanosomosis with more in the pipeline. Consortium scientists have placed many more cornerstones in the research framework to develop a vaccine to tackle this destructive disease in the African farming industry.
