In vitro study of protein release from AFCo1 and implications in mucosal immunisation

Adjuvant Finlay Cochleate 1 (AFCo1) is a Proteoliposome-derived cochleate obtained from Neisseria meningitidis serogroup B.Transformation of proteoliposomes into AFCo1 potentiates the immune response on Neisseria antigens when it is administered by intranasal or intragastric (i.g) routes. However, the i.n route has been demonstrated to be more effective. The aim of this work is to evaluate in vitro the protein release from AFCo1, in simulated gastric fluid (SGF) or simulated nasal fluid (SNF) using a microdissolution test and to provide support for the results found when AFCo1 was administered by i.g or i.n routes in BALB/c mice. Results showed that dilution of AFCo1 in simulated gastric fluid affects the delivery of Neisseria protein antigens because they were released from cochleate structures faster than when simulated nasal fluid was used. In conclusion, conditions simulating gastric environment affect the delivery of protein antigens from AFCo1 and this result could partially explain why i.n administration is more effective in vivo than i.g immunisation.