Mesoporous silica nanoparticles-based formulations of a chimeric proteinous vaccine candidate against necrotic enteritis disease

Highlights: • MSNPs are efficient adjuvants and delivery vehicles of a NE vaccine candidate. • Covalent conjugation of proteinous vaccine shows a prior immunization performance. • Orally administration of nanovaccines provides high protection in challenge tests. • Functionalized MSNPs show neglectable cytotoxicity effects. To develop a nanoparticle-based vaccine against necrotic enteritis, a chimeric antigen (rNA) consisting of the main antigens of Clostridium perfringens, NetB, and Alpha toxin, was prepared. Then, the rNA molecules were loaded onto the functionalized mesoporous silica nanoparticles (MSNPs) using physical adsorption or covalent conjugation methods. The characterization of synthesized nanoparticles was performed by scanning electron microscopy, dynamic light scattering, zeta potential measurement, Fourier transform infrared spectroscopy, and thermogravimetry techniques. The results revealed that the spherical nanoparticles with an average diameter of 90 ± 12 nm and suitable surface chemistries are prepared. MSNPs-based formulations did not show any significant toxicity on the chicken embryo fibroblast cells. The results of the challenge experiments using subcutaneous or oral administration of the as-prepared formulations in the animal model showed that the as-prepared nanosystems, similar to those formulated with a commercial adjuvant (Montanide), present stronger humoral immune responses as compared to that of the free proteins. It was also indicated that the best protection is obtained in groups vaccinated with MSNPs-based nanovaccine, especially those who orally received covalently conjugated nanovaccine candidates. These results recommend that the MSNPs-based formulated chimeric proteinous vaccine candidates can be considered as an effective immunizing system for the oral vaccination of poultry against gastrointestinal infectious diseases.