A Bacterial Protease Inhibitor is a Mucosal Adjuvant

Juliana Cassataro of the Universidad Nacional de San Martín-CONICET in Argentina will test whether the bacterial protease inhibitor Omp19 can make vaccines more effective when they are administered orally. Oral delivery of vaccines is far simpler than by injection, which is particularly useful in low-resource settings, and it may also stimulate mucosal immunity making them more effective against some diseases. However, most vaccines administered orally are degraded in the stomach or do not induce a sufficient immune response to protect against the disease. In Phase I, while at the Universidad de Buenos Aires-CONICET, they discovered that Omp19 protects antigens from degradation and serves as an adjuvant, contributing to induction of both a mucosal and systemic immune response in mice orally immunized with proteins from the Salmonella bacterium and the Toxoplasma parasite, both of which have mucosal routes of infection. In Phase II, they will extend their mechanistic studies in order to move towards a Phase I clinical trial, and evaluate the ability of Omp19 to help induce an immune response in mice upon oral vaccination against Enterotoxigenic E. coli (ETEC), which is the most common cause of bacterial diarrhea in children from developing countries.