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Huajun Zhao,1 Haigang Wang,1 Yifei Hu,1 Dongqing Xu,1 Chunlai Yin,2 Qiuju Han,1 Jian Zhang1 1Institute of Immunopharmaceutical Sciences, School of Pharmaceutical Sciences, Shandong University, Jinan, People’s Republic of China; 2Department of Immunology, Dalian Medical University, Dalian, People’s Republic of ChinaCorrespondence: Jian ZhangInstitute of Immunopharmaceutical Sciences, School of Pharmaceutical Sciences, Shandong University, Jinan, People’s Republic of ChinaTel +86-531-8838-3781Fax +86-531-8838-3782Email zhangj65@sdu.edu.cnPurpose: Alum adjuvant in HBV prophylactic vaccines is poor in inducing cellular immunity with the inhibition of IL-12 secretion, and approximately 5– 10% of immunised individuals fail to clear HBV upon infection. IL-12 plasmids (pIL-12) as adjuvants enhance significant humoral and cellular immune response in vaccines. However, finding a novel delivery system to protect pIL-12 from enzymatic degradation and achieve efficient delivery remains a major challenge.Methods: We prepared the chitosan nanovaccine-loaded IL-12 expression plasmid (termed as “Ng(-)pIL-12”) and analysed the physicochemical properties, encapsulation efficiency and safety. Then, we evaluated the efficiency of Ng(-)pIL-12 for prophylactic HBV vaccine. Serum samples were collected and analysed for IL-12, HBsAg, anti-HBs IgG, IgG1 and IgG2b. Liver tissues were collected and analysed for HBV DNA and RNA. BMDCs and lymphocytes were collected and analysed for HBV-specific immune responses. To further confirm the long-term protective immune response against HBV, these immunised mice were challenged with hydrodynamic injection of pAAV/HBV 1.2 plasmid on day 56 after the initiation of immunisation.Results: Chitosan nanovaccine prepared with CS and γ-PGA could load pIL-12 effectively and safely, and IL-12 was efficiently produced in vivo. Interestingly, Ng(-)pIL-12 adjuvant combined with HBsAg induced higher levels of anti-HBs IgG, IgG1 and IgG2b, promoted maturation and presentation capacity of DCs, especially CD8α+/CD103+ DCs. Meanwhile, Ng(-)pIL-12 adjuvant generated robust HBV-specific CD8+ T and CD4+ T cell responses. More importantly, Ng(-)pIL-12 adjuvant triggered terminally differentiated effector memory responses with strong anti-HBV effects.Conclusion: Chitosan nanovaccines as an efficient carrier adjuvant system for pIL-12 combined with HBsAg induced protective anti-HBs IgG and enhanced HBV-specific CD8+ T and CD4+ T cell responses, and achieved long-term memory response against HBV, making it a promising candidate for prophylactic HBV vaccines.Keywords: nanovaccines, hepatitis B, prophylactic vaccine, CD8+ T cells, long-term memory |
