Evaluation of PLG nanoparticles for encapsulation of outer membrane proteins of Salmonella Gallinarum and oral immunization in chicken

The particulate delivery system in the form of micro- and nanoparticles made up of biodegradable polymers such as poly-lactide-co-glycolide (PLG) are reported to be comparatively safe and very effective for antigen or drug delivery. In the present study, PLG nanoparticles were evaluated for oral delivery of OMP of Salmonella Gallinarum in chicken. PLG nanoparticles of various sizes were prepared encapsulating the OMP of S. Gallinarum by double emulsion solvent evaporation technique. The integrity of the protein released from nanoparticles was confirmed by SDS-PAGE analysis and the antigenicity was found unaltered in western blotting. The in vitro cellular uptake of OMP loaded nanoparticles in Raw. 264.7 cell line and subsequent release of proteins inside the cells was confirmed by detecting the proteins by IFAT and using confocal laser scanning microscope (CLSM). The OMP loaded nanoparticles were used for immunization trial in chicken by oral as well as intramuscular routes. The birds which were vaccinated intramuscularly, showed significantly higher levels of OMP specific IgY in serum samples as compared to the control birds, but they did not induce IgA antibody at mucosal sites. The birds which were vaccinated orally, showed higher IgA antibody levels in the intestinal secretions as compared to other groups indicating that PLG nanoparticles may be suitable for mucosal delivery of antigens in chicken.