This proposal has two overarching aims. The first aim is research-driven: we wish to understand the unusual behaviour of a a genome repair pathway termed nucleotide excision repair in two important human pathogens, Trypanosoma brucei (an African trypanosome, which is also an important animal pathogen) and Trypanosoma cruzi (a major parasite in South and Central America). Our rationale for this research is based on previous studies in T. brucei, which have suggested that the nucleotide excision repair machinery that acts to protect the parasite's genome from various forms of damage may have a different composition from what has been described in other organisms, including humans, and that some of the predicted machinery may in fact provide a different (and at the moment unknown) function in the cell. Currently, it is easier and quicker to do genetic experiments in T. brucei than in T. cruzi, and we will pioneer the nucleotide excision repair studies in the former and extend this work to the American trypanosome. In the second aim, we wish to run a residential meeting in Brazil on parasite genome repair and replication, with the purpose of fostering greater long-term links between Brazil and UK researchers in this area.