Engineering the gram-positive cell surface for construction of bacterial vaccine vectors

A genetic system for surface display of heterologous proteins has been deve loped in Streptococcus gordonii, a gram-positive human oral commensal that is naturally competent for genetic transformation. Our approach is based on chromosomal integration downstream from a resident promoter and translatio nal fusion to an M6 protein. Using this strategy a variety of proteins, of different origin and size, were displayed on the cell surface and were show n to be stably expressed both in vitro and in vivo. Animal models of mucosa l colonization (oral and vaginal) and intragastric immunization with recomb inant S. gordonii were developed and the local and systemic immune response s were studied. Here we report the techniques for the construction of recom binant bacteria, use of animal models, and analysis of the immune response. (C) 1999 Academic Press.