Bovine babesiosis: Molecular biology based tools for developing new vaccines

FARBER, MD

Mendoza, Argentina

Congreso; VII Congreso Argentino de Protozoología y Enfermedades Parasitarias; 2005

Sociedad Argentina de Protozoología

The protozoo Babesia bovis is the causative agent of babesiosis, a tick-borne disease that is a major cause of loss to livestock production in Latin America. Vaccination against Babesia species represents a major challenge agaist cattle morbidity and mortality in enzootic areas. The vaccine currently being used in many countries is a B. bovis attenuated strain blood-based one. The main disadvantages of this vaccines are cost, inadequate or variable efficacy, relative instability with the requirement of cold chain for distribution and risk of side reactions. Although several Babesia antigens have been identified that elicit immune responses attempts to produce vaccines composed of defined antigens have been disappointing. The main goal of our work is to develop new vaccines based on lived attenuated bacteria as carrier of heterologous antigens. For doing so we chose BCG (vaccine strain of the bovine tubercle bacillus)  and Brucella abortus vaccine strain (S19). We genetically modified them using specifically designed proper vectors for driving the expression for B. bovis antigens. We performed immunogenicity experiments in mice and a protection assay in bovines. On the other hand we are involved in an starting collaborative international project for pursuing a B. bovis vaccine strains attenuated by irreversible deletion of genes required for virulence and transmission. Comparative genomics will be used to identify genes required for pathogen virulence and transmission followed by knockout and replacement with marker sequences using transfection.