Hepatitis C virus E2 protein encapsulation into poly d, l-lactic-co-glycolide microspheres could induce mice cytotoxic T-cell response

Abstract

Hepatitis C virus (HCV) is known to cause hepatitis and hepatocellular carcinoma. E2 envelope glycoprotein of HCV type (HCV-E2) has been reported to bind human host cells and is a major target for developing anti-HCV vaccines. However, the therapeutic vaccine for infected patients still needs further development. The vaccine aims to provide cytotoxic T-cells to eliminate infected cells and hepatocellular carcinoma. Currently, there is no effective HCV therapeutic vaccine because most chronically infected patients rarely generate cytotoxic T-cells, even though they have high levels of neutralizing antibodies. Therefore, the adjuvant must be applied to enhance the efficacy of the therapeutic vaccine. In this study, we constructed HCV1b-E2 recombinant protein, a truncated form of peptide, to combine with an effective vaccine adjuvant and delivery system by using poly d,l-lactic-co-glycolide (PLGA) microspheres. HCV1b-E2 protein was effectively encapsulated into PLGA microspheres (HCV1b-E2-PLGA) as a strategy to deliver an insoluble form of HCV1b-E2 protein. The size and shape of PLGA microspheres were generated properly to carry an insoluble form of viral peptide in vivo. The encapsulated viral protein was slowly and continuously released from PLGA microspheres, which indicated the property of the adjuvant. HCV1b-E2-PLGA can trigger a cell-mediated immune response by inducing an expression of mice CD8⁺ T-cells. Our results demonstrated that HCV1b-E2-PLGA-immunized mice have a significantly increased CD8⁺ T-cell number, whereas HCV1b-E2-immunized mice have a lower number of CD8⁺ T-cells. Moreover, HCV1b-E2-PLGA could induce a specific antibody to viral protein, and the immune cells could secrete IFN-γ, which is a significant cytokine for viral response. Thus, HCV1b-E2-PLGA is shown to have adjuvant property and efficacy in the murine model, which is a good strategy to develop HCV prophylactic and therapeutic vaccines.

Keywords:

• hepatitis C virus
• HCV
• therapeutic vaccine
• PLGA microspheres
• HCV-E2 peptide
• cytotoxic T-cells
• hepatitis
• hepatocellular carcinoma

Acknowledgments

We thank Mr Wugen Zhan for his valuable help with flow cytometry analysis and other members of Huang Lab for suggestions and assistance. This work was supported by funding from Shenzhen Municipal Science, Technology & Innovation Commission’s Science & Technology Research Grants and the Municipal Program for Building State and Shenzhen Key Laboratories (2006464, 200712, SG200810150043A, CXB201005260070A, CXB201104220043A, ZDSY20120616222747467, JCYJ20130402145002438, ZDSYS20140509172959975, GJHZ20140416153844269, and JCYJ20140418112611757), and in part from Shenzhen Municipal and Nanshan District Science & Technology Grants (JCYJ20140718171607436 and KC2014JSCX0023A).

Author contributions

LH and PR conceived and designed the research; PR conducted most of the research; all authors contributed toward data analysis, drafting and revising the paper and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.