Oral vaccination using recombinant bacteria.

With the development of avirulent but immunogenic Salmonella strains it has become possible to deliver heterologous antigens to the mucosal and systemic immune system by the oral route. The basis of attenuation of different Salmonella mutants and the immune response to foreign antigens expressed by recombinant strains is discussed, as are problems related to the stabilisation of foreign genes in Salmonella and to the expression of immunogenic antigens.