Genetically engineered M13 phage-mediated H9N2 DNA vaccine with enhanced mucosal and systemic immune responses in mice

TL;DR

A new DNA vaccine delivery system using engineered M13 phage and nanoparticles boosts immune responses and protection against H9N2 bird flu in mice.

Contribution

A novel DNA vaccine platform combining genetically engineered M13 phage and chitosan-based nanoparticles is developed for enhanced immune responses.

Findings

The composite nanoparticles effectively protect and deliver the HA gene while promoting immune cell maturation.

Mice immunized with the new vaccine showed higher antibody levels and longer protection than a commercial vaccine.

The vaccine enhanced both mucosal and systemic immune responses, including increased cytokine and T cell levels.

Abstract

Vaccine adjuvants and delivery systems have long been used in DNA vaccines to enhance immunogenicity. In this study, we developed a DNA vaccine delivery platform by combining N-2-hydroxypropyl trimethyl ammonium chloride chitosan/carboxymethyl chitosan nanoparticles (N-2-HACC/CMCS NPs) with a genetically engineered M13 phage containing the HA gene of H9N2 AIV (HA-M13). The composite NPs (HA-M13/N-2-HACC/CMCS) had an average particle size of 135.24 ± 4.36 nm, and the HA gene encapsulated in the composite NPs could be expressed in vitro. Additionally, the N-2-HACC/CMCS NPs exhibited high stability and effectively protected the HA gene and M13 phage from degradation while sustaining antigen release. Furthermore, the N-2-HACC/CMCS NPs promoted the maturation of DC2.4, enhanced MHC I and MHC II pathways and improved cellular, humoral, and mucosal immune responses. Mice immunized with HA-M13/N-2-HACC/CMCS via nasal and intramuscular injections presented higher anti-H9N2 AIV antibody titers than those given the commercial vaccine. Lymphocyte proliferation, as well as the levels of the cytokines IL-2, IL-4, IFN-γ, CD4+, and CD8+ T lymphocyte levels, also significantly increased. The nanovaccine provided effective protection against H9N2 AIV infection for 154 days postimmunization, surpassing the 120-day protection provided by the commercial vaccine. Consequently, the N-2-HACC/CMCS NPs loaded with M13 phages exhibit significant potential as vaccine adjuvants and mucosal immune delivery system.

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