There is much interest in developing attenuated Salmonella typhimurium as a vehicle for introducing foreign genes into an experimental animal. This system can be used to test the protective capacity of any gene product, as well as to determine the presence of B and T cells epitopes of the gene product. Although there is much effort expended in developing a S. typhimurium strain that is both avirulent and protective, there has been little or no work done to develop a general-use vector for expressing the foreign genes. We propose to construct a vector for the rapid cloning and stable expression of foreign genes in attenuated S. typhimurium. This vector could be used for cloning and expression of well characterized genes, as well as for making a cDNA or other type of expression gene bank in this bacterium. We will use this expression vector for testing the potential of several parasite gene products in eliciting a protective immune response in the animal host. In addition, we will continue our work in the characterization of a T. cruzi trypomastigote specific protein which elicits antibodies that mediate complement dependent lysis of the parasite. The work we propose to do involves a mixture of standard bacterial genetics, DNA and protein biochemistry, and basic immunologic techniques.
