The innate immune receptors and pathways involved in pathogen recognition are the subject of intense research. However, our overall understanding of the complex interactions between innate immunity and infectious agents is still limited. In this meeting, we plan to address the following main points: (i) molecular events of innate recognition and host cell activation by infectious agents; (ii) innate mechanisms of pathogen elimination or persistence in host cells; (iii) the consequences of activation/evasion of specific innate immune pathways on microbial pathogenesis and disease outcome; (iv) the role of innate immunity in the development of beneficial versus deleterious acquired immune responses during infectious diseases; and (v) manipulation of specific innate immune pathways for therapeutic and prophylactic intervention in infectious diseases. A major emphasis of the scientific program will be on infectious diseases of the tropics, where the role of innate immunity is less well understood. It is hoped that the symposium will generate a new understanding of host-pathogen interactions that regulate host resistance versus disease outcomes and by so doing contribute to the design of new strategies for immunological intervention. The rational development of immunological interventions that are effective for treating or preventing infectious diseases is still on its infancy. For decades, the majority of the studies on immunopathogenesis have dealt with physical damage and inflammation, primarily mediated by the adaptive immune system.. The main focus of our scientific program will be on the interface of the innate immunity and microbial pathogens, as a key step that is determinant of protective versus deleterious immune responses, and thereby of the outcome of disease. The meeting will promote discussions on fundamental concepts as well as new advances in the role of innate immunity in host resistance and pathogenesis of infectious diseases, with significant emphasis on infections of the tropics. Investigators from different areas, such as biochemistry, cell biology, immunology, microbiology, parasitology, infectious diseases, tropical medicine and biotechnology will be included to encourage the discussion of interdisciplinary concepts and new directions for the field. This is the first of a series of Keystone Symposia meetings to be held in Brazil, and should also foster the participation of Latin American students and scientists. The close interaction of these participants with leading international experts in the field should lead to a stimulating atmosphere that we hope will promote the development of new South-North collaborations and research networks.