Immunogenicity of the nanovaccine containing intimin recombinant protein in the BALB/c mice

Oral organic nanovaccines against bacterial and viral diseases

Vaccines have saved millions of humans and animals from deadly diseases. Many vaccines are still under development to fight against lethal diseases. Indeed, subunit vaccines are a versatile approach with several advantageous attributes, but they lack strong immunogenicity. Nanotechnology is an avenue to vaccine development because nanoparticles may serve as nanocarriers and adjuvants, which are critical aspects for oral vaccines. This review provides an update of oral organic nanovaccines, describing suitable nanomaterials for oral vaccine design and recent (last five-year view) oral nanovaccine developments to fight against those principal pathogens causing human and animal diseases.

Demystifying particle-based oral vaccines

Introduction: The oral route of vaccination is pain- and needle-free and can induce systemic and mucosal immunity. However, gastrointestinal barriers and antigen degradation impose significant hurdles in the development of oral vaccines. Live attenuated viruses and bacteria can overcome these barriers but at the risk of introducing safety concerns. As an alternative, particles have been investigated for antigen protection and delivery, yet there are no FDA-approved oral vaccines based on particle-based delivery systems. Our objective was to discover underlying determinants that can explain the current inadequacies and identify paradigms that can be implemented in future for successful development of oral vaccines relying on particle-based delivery systems.Areas covered: We reviewed literature related to the use of particles for oral vaccination and placed special emphasis on formulation characteristics and administration schedules to gain an insight into how these parameters impact production of antigen-specific antibodies in systemic and mucosal compartments.Expert opinion: Despite the long history of vaccines, particle-based oral vaccination is a relative new field with the first study published in 1989. Substantial variability exists between different studies with respect to dosing schedules, number of doses, and the amount of vaccine per dose. Most studies have not used adjuvants in the formulations. Better standardization in vaccination parameters is required to improve comparison between experiments, and adjuvants should be used to enhance the systemic and mucosal immune responses and to reduce the number of doses, which will make oral vaccines more attractive.

Chitosan Nanoparticles Loaded with Truncated ORF2 Protein as an Oral Vaccine Candidate against Hepatitis E

In a continuous effort to develop effective vaccines against hepatitis E (HE), oral vaccine nanoparticles using the truncated capsid protein p146 (aa460-605) are formulated and characterized. To improve the immunogenicity of p146, chitosan nanoparticles (CSNPs) are used as a mucosal delivery system. Next, the physical-chemical properties, cytotoxic effects in vitro, and immunogenicity in mice of the produced NPs are analyzed. The results show that the produced CS/p146 NPs are stable and well dispersive and display a near-spherical shape with a mean size of 200-300 nm. The findings also demonstrate high encapsulation efficiency (65-73.9%) and loading capacity (27.7-67.5%) of the formulated nanoparticles. Further, the CS/p146 NPs exhibit low cytotoxicity and an obvious sustained-release effect in vitro. Immunogenicity experiments in mice indicate that CS/p146 NPs can induce antigen-specific systemic and mucosal immune responses higher than the purified p146 do. Besides, the expression levels and mRNA transcription of Interleukin (IL)-4 in spleen cells of CS/p146 NPs-immunized mice are higher than those of p146, indicating that a Th2-mediated cellular immune response is activated by the CS/p146 NPs. Overall, the synthesized CS/p146 NPs display promising properties as a potential HE oral vaccine candidate.

Potential improvement of the immune response of chickens against E. coli vaccine by using two forms of chitosan nanoparticles

Colibacillosis disease has an important economic impact on poultry production worldwide. It is one of the most common causes of mortality in commercial layer and breeder chickens. Avian pathogenic Escherichia coli (APEC) is the main cause of this disease. Nanoparticles have been widely used in vaccine design as both adjuvants and antigen delivery vehicles. The present study aimed to produce an efficient vaccine from E. coli serogroups O1 and O78 to help in controlling colibacillosis in chicken using two forms of chitosan (CS) and ascorbate chitosan (AsCS) nanoparticles. Nanovaccines has been prepared through loading and encapsulation of outer membrane and flagellar antigen on CS and AsCS nanoparticles with loading efficiency 86, 63,55, 48% for CS-loaded-, Cs-capsulated-, AsCS-loaded- and AsCS-capsulated-E. coli Antigen, respectively. Two hundred specific pathogens free (SPF) 3-weeks old broiler chickens were used and divided into four groups to investigate the immune response of nanovaccines. The immune response was measured by the microagglutination, ELISA, and challenge test. From results, it could be concluded that generally adding chitosan NPs is capable of improving vaccine efficacy via the induction of strong immunity. Moreover, we recommend the production of the nanovaccine CS-capsulated -antigen from E. coli O1 and O78 serotypes to be used as a potent vaccine to aid in controlling colibacillosis. Also, the ascorbate chitosan is a great alternate for the initiation of a potent immune response in critical infection cases.

Immunization against Vibrio cholerae, ETEC, and EHEC with chitosan nanoparticle containing LSC chimeric protein

INTRODUCTION

Severe intestinal infections caused by V. cholerae, ETEC and EHEC have contributed to the mortality rate in developing countries. Vibrio Cholera, ETEC and EHEC bacterium with the production of CT, LT and Stx2 toxins respectively lead to severe watery and bloody diarrhea. This study aimed to investigate a trimeric vaccine candidate containing recombinant chimeric protein, encapsulate the protein in chitosan nanoparticles and assess its immunogenicity.

METHODS

The LSC recombinant gene was used. It is composed of LTB (L), STXB (S) and CTXB (C) subunits respectively. The LSC recombinant protein was expressed and purified and confirmed by western blotting. The purified protein was encapsulated in chitosan nanoparticles, and its size was measured. BalB/c mice were immunized in four groups through oral and injection methods by LSC protein. The antibody titer was then evaluated by ELISA, and finally, the challenge test of the toxins from all three bacteria was done on the immunized mouse.

RESULTS

After expression and purification LSC protein size of nanoparticles containing protein was measured at 104.6 nm. Nanoparticles were able to induce systemic and mucosal immune responses by generating a useful titer of IgG and IgA. The challenge results with LT, CT and Stx toxins showed that the LSC protein might partially neutralize the effect of toxins.

CONCLUSION

LSC chimeric protein with the simultaneous three essential antigens have a protective effect against the toxins produced by ETEC, EHEC and Vibrio cholera bacteria and it can be used in vaccines to prevent Diarrhea caused by these three bacteria.