Bacteria with altered DNA adenine methylase (DAM) activity and heterologous epitope

摘要: Immunogenic compositions are disclosed which are comprised of bacteria which are pathogenic in their native state but which are rendered non-pathogenic in a manner which alters the native level or activity of DNA adenine methylase. The genome is also artificially engineered to express a heterologous antigen such as an immunogenic antigen of a virus, protozoa, parasite or fungi.