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DNA immunization with fusion of CTLA-4 to hepatitis B virus (HBV) core protein enhanced Th2 type responses and cleared HBV with an accelerated kinetic.

Yin Y, Wu C, Song J, Wang J, Zhang E, Liu H, Yang D, Chen X, Lu M, Xu Y - PLoS ONE (2011)

Bottom Line: However, plasmids expressing viral proteins fused to cytotoxic T lymphocyte antigen 4 (CTLA-4) primed Th2-biased responses and were able to induced effective protection against viral challenge in the woodchuck model.HBV surface antigen (HBsAg) and DNA in peripheral blood and HBcAg in liver tissue were cleared with significantly accelerated kinetics in both groups.Viral clearance could be efficiently achieved by Th1/Th2-balanced immune response, with a small but significant shift in T-cell and B-cell immune responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.

ABSTRACT

Background: Typically, DNA immunization via the intramuscular route induces specific, Th1-dominant immune responses. However, plasmids expressing viral proteins fused to cytotoxic T lymphocyte antigen 4 (CTLA-4) primed Th2-biased responses and were able to induced effective protection against viral challenge in the woodchuck model. Thus, we addressed the question in the mouse model how the Th1/Th2 bias of primed immune responses by a DNA vaccine influences hepatitis B virus (HBV) clearance.

Principal findings: Plasmids expressing HBV core protein (HBcAg) or HBV e antigen and HBcAg fused to the extracellular domain of CTLA-4 (pCTLA-4-HBc), CD27, and full length CD40L were constructed. Immunizations of these DNA plasmids induced HBcAg-specific antibody and cytotoxic T-cell responses in mice, but with different characteristics regarding the titers and subtypes of specific antibodies and intensity of T-cell responses. The plasmid pHBc expressing HBcAg induced an IgG2a-dominant response while immunizations of pCTLA-4-HBc induced a balanced IgG1/IgG2a response. To assess the protective values of the immune responses of different characteristics, mice were pre-immunized with pCTLA-4-HBc and pHBc, and challenged by hydrodynamic injection (HI) of pAAV/HBV1.2. HBV surface antigen (HBsAg) and DNA in peripheral blood and HBcAg in liver tissue were cleared with significantly accelerated kinetics in both groups. The clearance of HBsAg was completed within 16 days in immunized mice while more than 50% of the control mice are still positive for HBsAg on day 22. Stronger HBcAg-specific T-cell responses were primed by pHBc correlating with a more rapid decline of HBcAg expression in liver tissue, while anti-HBs antibody response developed rapidly in the mice immunized with pCTLA-4-HBc, indicating that the Th1/Th2 bias of vaccine-primed immune responses influences the mode of viral clearance.

Conclusion: Viral clearance could be efficiently achieved by Th1/Th2-balanced immune response, with a small but significant shift in T-cell and B-cell immune responses.

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Specific T-cell responses to HBcAg and HBsAg epitopes in mice after HI.The specific T-cell responses to the CTL epitope HBcAg aa 87-95 and HBsAg aa 29-38 in mice immunized with pHBc, pCTLA-4-HBc, and PBS after HI of pAAV/HBV1.2. HBcAg (A) and HBsAg (B)-specific T-cell responses were detected by ELISpot after HI challenge at days 1, 4, 7, 10 and 20, and are presented as spot-forming cells per 2×105 cells.
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pone-0022524-g006: Specific T-cell responses to HBcAg and HBsAg epitopes in mice after HI.The specific T-cell responses to the CTL epitope HBcAg aa 87-95 and HBsAg aa 29-38 in mice immunized with pHBc, pCTLA-4-HBc, and PBS after HI of pAAV/HBV1.2. HBcAg (A) and HBsAg (B)-specific T-cell responses were detected by ELISpot after HI challenge at days 1, 4, 7, 10 and 20, and are presented as spot-forming cells per 2×105 cells.

Mentions: The clearance of HBsAg and HBV DNA occurred rapidly in immunized mice within three weeks. To judge the involvement of specific T-cells, HBV-specific CTL responses were detected at days 1, 4, 7, 10 and 20 after HI challenge by ELISpot assay of IFN-γ producing cells. In control mice, IFN-γ producing cells stimulated with peptides HBcAg aa 87–95 and HBsAg aa 29–38 representing CTL epitopes were hardly detectable. In both immunized mice groups, IFN-γ producing cells stimulated with HBcAg peptide were detectable at day 1 after HI (Fig. 6A). The number of IFN-γ producing cells reached the peak in pHBc-immunized mice at day 7 after HI challenge, and was significantly higher than that in pCTLA-4-HBc immunized mice (p = 0.021) (Fig. 6A). At day 10 and 20, the response to HBcAg peptide remained high and was comparable in both immunized groups. In addition, the immunized mice also developed specific responses to HBsAg peptide. The HBsAg-specific T-cell response reached the peak at day 7 after HI challenge in pHBc-immunized mice (Fig. 6B). Interestingly, the numbers of HBsAg-specific T-cells in the pCTLA-4-HBc immunized mice increased continuously up to day 20 (Fig. 6B).


DNA immunization with fusion of CTLA-4 to hepatitis B virus (HBV) core protein enhanced Th2 type responses and cleared HBV with an accelerated kinetic.

Yin Y, Wu C, Song J, Wang J, Zhang E, Liu H, Yang D, Chen X, Lu M, Xu Y - PLoS ONE (2011)

Specific T-cell responses to HBcAg and HBsAg epitopes in mice after HI.The specific T-cell responses to the CTL epitope HBcAg aa 87-95 and HBsAg aa 29-38 in mice immunized with pHBc, pCTLA-4-HBc, and PBS after HI of pAAV/HBV1.2. HBcAg (A) and HBsAg (B)-specific T-cell responses were detected by ELISpot after HI challenge at days 1, 4, 7, 10 and 20, and are presented as spot-forming cells per 2×105 cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3142188&req=5

pone-0022524-g006: Specific T-cell responses to HBcAg and HBsAg epitopes in mice after HI.The specific T-cell responses to the CTL epitope HBcAg aa 87-95 and HBsAg aa 29-38 in mice immunized with pHBc, pCTLA-4-HBc, and PBS after HI of pAAV/HBV1.2. HBcAg (A) and HBsAg (B)-specific T-cell responses were detected by ELISpot after HI challenge at days 1, 4, 7, 10 and 20, and are presented as spot-forming cells per 2×105 cells.
Mentions: The clearance of HBsAg and HBV DNA occurred rapidly in immunized mice within three weeks. To judge the involvement of specific T-cells, HBV-specific CTL responses were detected at days 1, 4, 7, 10 and 20 after HI challenge by ELISpot assay of IFN-γ producing cells. In control mice, IFN-γ producing cells stimulated with peptides HBcAg aa 87–95 and HBsAg aa 29–38 representing CTL epitopes were hardly detectable. In both immunized mice groups, IFN-γ producing cells stimulated with HBcAg peptide were detectable at day 1 after HI (Fig. 6A). The number of IFN-γ producing cells reached the peak in pHBc-immunized mice at day 7 after HI challenge, and was significantly higher than that in pCTLA-4-HBc immunized mice (p = 0.021) (Fig. 6A). At day 10 and 20, the response to HBcAg peptide remained high and was comparable in both immunized groups. In addition, the immunized mice also developed specific responses to HBsAg peptide. The HBsAg-specific T-cell response reached the peak at day 7 after HI challenge in pHBc-immunized mice (Fig. 6B). Interestingly, the numbers of HBsAg-specific T-cells in the pCTLA-4-HBc immunized mice increased continuously up to day 20 (Fig. 6B).

Bottom Line: However, plasmids expressing viral proteins fused to cytotoxic T lymphocyte antigen 4 (CTLA-4) primed Th2-biased responses and were able to induced effective protection against viral challenge in the woodchuck model.HBV surface antigen (HBsAg) and DNA in peripheral blood and HBcAg in liver tissue were cleared with significantly accelerated kinetics in both groups.Viral clearance could be efficiently achieved by Th1/Th2-balanced immune response, with a small but significant shift in T-cell and B-cell immune responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.

ABSTRACT

Background: Typically, DNA immunization via the intramuscular route induces specific, Th1-dominant immune responses. However, plasmids expressing viral proteins fused to cytotoxic T lymphocyte antigen 4 (CTLA-4) primed Th2-biased responses and were able to induced effective protection against viral challenge in the woodchuck model. Thus, we addressed the question in the mouse model how the Th1/Th2 bias of primed immune responses by a DNA vaccine influences hepatitis B virus (HBV) clearance.

Principal findings: Plasmids expressing HBV core protein (HBcAg) or HBV e antigen and HBcAg fused to the extracellular domain of CTLA-4 (pCTLA-4-HBc), CD27, and full length CD40L were constructed. Immunizations of these DNA plasmids induced HBcAg-specific antibody and cytotoxic T-cell responses in mice, but with different characteristics regarding the titers and subtypes of specific antibodies and intensity of T-cell responses. The plasmid pHBc expressing HBcAg induced an IgG2a-dominant response while immunizations of pCTLA-4-HBc induced a balanced IgG1/IgG2a response. To assess the protective values of the immune responses of different characteristics, mice were pre-immunized with pCTLA-4-HBc and pHBc, and challenged by hydrodynamic injection (HI) of pAAV/HBV1.2. HBV surface antigen (HBsAg) and DNA in peripheral blood and HBcAg in liver tissue were cleared with significantly accelerated kinetics in both groups. The clearance of HBsAg was completed within 16 days in immunized mice while more than 50% of the control mice are still positive for HBsAg on day 22. Stronger HBcAg-specific T-cell responses were primed by pHBc correlating with a more rapid decline of HBcAg expression in liver tissue, while anti-HBs antibody response developed rapidly in the mice immunized with pCTLA-4-HBc, indicating that the Th1/Th2 bias of vaccine-primed immune responses influences the mode of viral clearance.

Conclusion: Viral clearance could be efficiently achieved by Th1/Th2-balanced immune response, with a small but significant shift in T-cell and B-cell immune responses.

Show MeSH
Related in: MedlinePlus