Oral immunization of adult volunteers with microencapsulated enterotoxigenic Escherichia coli (ETEC) CS6 antigen.

As a step in the development of an oral vaccine against ETEC, we evaluated the safety and immunogenicity of CS6, a polymeric protein commonly found on the surface of ETEC. Formulations included 1 and 5mg doses of CS6, either encapsulated in biodegradable polymer poly(D, L)-lactide-co-glycolide (PLG), or as free protein, administered orally in a solution of either normal saline or a rice-based buffer. Three doses of CS6 were given at 2-week intervals.