Conclusion
The results obtained in this research place OMVs among promising candidates to be used for vaccination.
Methods
OMVs was purified from bacterial supernatant by ultracentrifugation. OMVs were encapsulated in chitosan nanoparticles prepared by ionic gelation method within a layer of Eudragit L100 for oral delivery. Female BALB/c mice of 9 weeks' old were immunized by parenteral injection and oral administration with free and encapsulated OMVs obtained from bacteria cultivated at 37°C and 42°C. The serum samples were collected and the antibody titers were measured by an enzyme-linked immunosorbent assay (ELISA).
Results
The protein concentrations of OMVs were 3.47 mg/ml and 2.46 mg/ml for bacteria grown at 37°C and 42°C respectively. OMVs loaded into nanoparticles (NP-OMVs) were homogeneous and spherical in shape, with a size of 532 nm. The encapsulation efficiency of NP was 90%. Mice immunized with OMVs, inhibited the ETEC colonization in their small intestine and induced production of antibodies against LT toxin.