Chitosan-Based Intranasal Vaccine against Escherichia coli O157:H7

Background: Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is an infectious zoonotic pathogen causing human infections. These infections, in some cases, can lead to hemolytic uremic syndrome and its life-threatening complications and even death worldwide. The first intimate bacterial adhesion, intimin (I), with its own receptor translocated intimin receptor (Tir) and E. coli secreted protein A, acting as Tir conduit, are highly immunogenic proteins for vaccine development against E. coli O157:H7. Methods: A chimeric trivalent recombinant protein was previously found to be a suitable strategy for developing vaccines against E. coli O157:H7. In this study, the recombinant EIT (rEIT) was used to design a protective EHEC nasal nanovaccine. Chitosan and its water-soluble derivative, trimethylated chitosan (TMC), as muco-adhesive biopolymers, are good candidates for preparation of nanovaccines.  Using the electrospraying technique, as a novel method, we could obtain particles of rEIT loaded with chitosan and TMC on a nanometer scale. Mice were immunized with intranasal administration or intrapretoneal injection of rEIT. Results: The rEIT-specific immune responses (IgG and IgA) were measured by indirect ELISA. Only nasal administration of chitosan electrospray and TMC formulation produced significant secretion IgA. Intranasal administration of nanovaccine reduced the duration of bacterial fecal shedding on mice challenged with E. coli O157:H7. Conclusion: Since development of mucosal vaccines for the prevention of infectious diseases requires efficient antigen delivery therefore, this research could be a new strategy for developing vaccine against E. coli O157:H7.