Development and evaluation of porous chitosan nanoparticles for treatment of enterotoxigenic Escherichia coil infection.

Enterotoxigenic Escherichia coil (ETEC) infections result in large mortality rate and usually a frequent cause of diarrhea in infants and a major cause of economic losses in the swine industry. To prevent enterotoxigenic Escherichia coli infections animal needs an active mucosal immunity at the moment of weaning. In the present study, F4 loaded porous chitosan nanoparticles were prepared by spray drying method for oral vaccination. In order to prevent the release the antigen in upper GI tract and to release it at target site nanoparticles were coated with Eudragit L100 which protect the antigen against the detrimental effects in the gastro-intestinal tract. Average size of prepared nanoparticles varied between 548 +/- 2.3 to 98 +/- 1.1 nm with a polydispersity index ranging from 0.767 +/- 0.023 to 0.209 +/- 0.021. Zeta potential for prepared nanoparticles was found to be in range from +18.3 +/- 2.5 to +29.5 +/- 2.8 mV. SEM studies completely revealed that the drug loaded nanoparticles were found to be distinct, spherical in shape with pores formed. Practicability of NPs was compared to vaccination with F4 fimbriae in solution. Mucosal immune response study revealed that, immune response were elicited in solution was well as in NPs group but colonization of the small intestine by F4+ ETEC upon oral solution challenge could not be prevented. However animals vaccinated with porous NPs group reveal a significant reduction in excretion of F4+ E. coli. Studies indicate that a solid vaccine formulation will be more efficient as compared to oral solutions. These systems can contribute to the development of oral vaccines in veterinary as well as in human medicines.