In collaboration with Professor Ian Henderson from the Institute of Microbiology and Infection, the proposed three month program will improve existing research networks between the University of the State of Rio de Janeiro and the world leading scientific group at the University of Birmingham. The project will define for the first time the gene essentiality in Corynebacterium diphtheriae, the causative agent of Diphtheria. Diphtheria is well controlled in vaccinated populations, however, the decline of vaccinations in certain parts of the world hasled to a resurgence in cases of Diphtheria and the emergence of non-toxigenic disease causing lineages of this bacterium. Working together, we have created a high density transposon insertion library in a non-toxigenic strain of C. diphtheriae isolated from an ill patient. This will allow us to identify all genes that are essential for viability which can be targeted for novel therapeutic strategies. During the project we can exploit this library to identify all conditionally essential genes, e.g. those required for resistance to complement dependent killing or those that are required for infecting the host. This information will provide an unprecedented level of understanding of an important human pathogen.