Development of oral vaccines for human use.

In developed and developing countries, oral vaccine formulations that elicit protection at mucosal surfaces are attractive vaccine candidates. Research has shown that vaccine delivery using either viral or non-viral vector delivery of heterologous proteins via the oral route is highly effective. Improvements in non-viral vector uptake, specific targeting, antigen presentation and antigen release times will be required to overcome differences in the immune response following delivery. In contrast, the use of plant and animal viruses as vectors provides an effective method for targeted gene delivery. Recently, recombinant plant viruses grown in plants or transgenic plants have been proposed as edible vaccines for human use. Food plants offer many advantages as affordable, oral vaccines, especially for use in developing countries. Further research is necessary to develop strategies to improve immunological memory following oral vaccination and to avoid immunological tolerance in the host.