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The effectiveness of inactivated H9N2 influenza vaccines is doubtful due to changes in antigenic regions of the virus hemagglutinin (HA) protein. One strategy for the development of the efficacious vaccine is the use of nanoparticles that display more immunogenic regions of the influenza virus. In this study, chitosan (CS)-based nanoparticles were developed as a delivery system for intranasal immunization using recombinant H9N2 virus HA1 and nucleoprotein (NP), for the induction of humoral and cellular responses. CS-HA1 and CS-NP nanoparticles were prepared by the ionic gelation method and characterized for their physicochemical properties and shape. The immunogenicity and the protective efficacy were evaluated by measuring antibody titers, T cell proliferation response, CD4+/CD8+ ratio, and quantitative real-time RT-PCR following intranasal administration of the prepared nanoparticles alone or in combination in chickens compared to an inactivated H9N2 vaccine. The average size, surface charge, and spherical structure of the synthesized nanoparticles showed high quality. Serologic analysis revealed that the immunization of inactivated vaccine groups resulted in strong influenza antibodies, which were significantly (p < 0.05) higher compared to the other groups. The vaccinated chickens with CS-HA1+CS-NP developed higher specific anti-influenza antibodies than in those vaccinated with each of rHA1 and rNP. Administration of a combination of the protein-based nanoparticles has stimulated the activation of both CD4+ and CD8+T cells and induced a significantly higher T cell proliferation. The viral shedding was significantly lower in CS-HA1+CS-NP and inactivated vaccine groups compared with other challenged groups. The data demonstrate the potential of CS-HA1+CS-NP nanoparticles for eliciting specific influenza antibodies and conferring protection in chickens. [ABSTRACT FROM AUTHOR]

Despite the robust induction of humoral immune responses, a limitation of many adjuvants is their weak stimulation of cellular immunity. The development of synthetic gene-encoding adjuvants for simultaneous induction of both humoral and cell-mediated immune responses is under study. In this study, we examined the impact of toll/interleukin-1 receptor (TIR) domain of toll-like receptor 7 (TLR7) as molecular adjuvants on potency of inactivated infectious bursal disease (IBD) vaccines. A total of 60 specific pathogen-free week-old chicks were randomized grouped to receive either TIR-TLR7-adjuvanted IBD-inactivated vaccine or inactivated IBD antigen along with an unvaccinated control. Serum antibody titers were measured to estimate the humoral immunity, as well as lymphocyte proliferation activity for cellular immune responses. The protection was estimated after challenge with a very virulent IBD virus (IBDV) strain at 4 weeks postvaccination. The results indicated that one dose of IBD/TIR-TLR7 vaccine induced specific antibody responses, whereas a lower response after administration of inactivated IBD antigen was observed. The stimulation of splenocytes results indicated that the TIR-TLR7 adjuvanted IBD vaccine is capable of modulating cell-mediated immune response in treated chickens. A full protection against IBDV infection was achieved by injection of one dose IBD/TIR-TLR7 vaccine in the challenge trial. This study demonstrated that codelivery of TIR-TLR7 with inactivated IBD antigen resulted in simultaneous enhancing immune responses against IBD. [ABSTRACT FROM AUTHOR]