The main expertise of the research group GEVI is molecular genetics of bacteria that are pathogenic for plants and animals. This laboratory contributed significantly to the present widespread application of the bacterium Agrobacterium tumefaciens, as a tool for routine transformation of plants. Agrobacterium- mediated transformation is used by GEVI for the isolation and study of genes involved in plant morphogenesis. In addition, techniques for the transformation of leguminous crop plants are developed and the expression in plants of lectins with insecticidal activity is optimised. The virulence mechanisms of bacteria (Escherichia coli and Salmonella) pathogenic for humans and domestic animals are studied, by the isolation and analysis of the relevant genes. Several gene clusters, encoding fimbriae involved in the adhesion of pathogenic E. coli to host tissues, were cloned and analysed in detail. New genes involved in the pathogenicity of S.enteritidis for mammals and birds were also identified. Besides providing new insights in these complex interactions, this also leads to the development of more specific diagnostics and improved vaccines for the control of these important pathogens. The controlled expression of viral antigens in attenuated Salmonella vaccine strains, to produce recombinant anti-viral vaccines, is also investigated.