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Gene Expression Driven by a Strong Viral Promoter in MVA Increases Vaccination Efficiency by Enhancing Antibody Responses and Unmasking CD8⁺ T Cell Epitopes.

Becker PD, Nörder M, Weissmann S, Ljapoci R, Erfle V, Drexler I, Guzmán CA - Vaccines (Basel) (2014)

Bottom Line: T cells recognizing determinants derived from late viral proteins have a clear disadvantage to proliferate during secondary responses.Although the Ag-expression from the natural promoter 7.5 (P7.5) and the mPH5 seemed similar, detailed analysis showed that mPH5 not only induces higher expression levels than P7.5 during early phase of infection, but also Ag turnover is enhanced.The strong overexpression during the early phase leads to broader CD8 T cell responses, while preserving the priming efficiency of stable Ags.

View Article: PubMed Central - PubMed

Affiliation: Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, D-38124 Braunschweig, Germany. pablo.becker@kcl.ac.uk.

ABSTRACT
Viral vectors are promising tools for vaccination strategies and immunotherapies. However, CD8⁺ T cell responses against pathogen-derived epitopes are usually limited to dominant epitopes and antibody responses to recombinant encoded antigens (Ags) are mostly weak. We have previously demonstrated that the timing of viral Ag expression in infected professional Ag-presenting cells strongly shapes the epitope immunodominance hierarchy. T cells recognizing determinants derived from late viral proteins have a clear disadvantage to proliferate during secondary responses. In this work we evaluate the effect of overexpressing the recombinant Ag using the modified vaccinia virus early/late promoter H5 (mPH5). Although the Ag-expression from the natural promoter 7.5 (P7.5) and the mPH5 seemed similar, detailed analysis showed that mPH5 not only induces higher expression levels than P7.5 during early phase of infection, but also Ag turnover is enhanced. The strong overexpression during the early phase leads to broader CD8 T cell responses, while preserving the priming efficiency of stable Ags. Moreover, the increase in Ag-secretion favors the induction of strong antibody responses. Our findings provide the rationale to develop new strategies for fine-tuning the responses elicited by recombinant modified vaccinia virus Ankara by using selected promoters to improve the performance of this viral vector.

No MeSH data available.


Related in: MedlinePlus

DC expression of MHC class I depends on the MOI of MVA. DCs were infected with nrMVA, MVA-OVA P7.5, and MVA-OVA mPH5 at different MOIs for 6 h. After washing and further incubation for 16 h, changes in the expression of MHC class I were measured by flow cytometry. The MOIs of 0.05, 0.5, and 5 were arbitrarily considered as representative of low, intermediate, and high MOI, respectively (open histograms). Mock infected DCs (MVA = 0, shaded histogram) were considered as a basal level of MHC class I expression. Numbers in the upper right corners indicate fold-changes as %.
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vaccines-02-00581-f003: DC expression of MHC class I depends on the MOI of MVA. DCs were infected with nrMVA, MVA-OVA P7.5, and MVA-OVA mPH5 at different MOIs for 6 h. After washing and further incubation for 16 h, changes in the expression of MHC class I were measured by flow cytometry. The MOIs of 0.05, 0.5, and 5 were arbitrarily considered as representative of low, intermediate, and high MOI, respectively (open histograms). Mock infected DCs (MVA = 0, shaded histogram) were considered as a basal level of MHC class I expression. Numbers in the upper right corners indicate fold-changes as %.

Mentions: It has been previously reported that nrMVA induces down-regulation of MHC class I expression. As expected, DCs infected with nrMVA showed a drastic decrease in the expression of MHC class I in a MOI-dependent manner. However, MHC class I expression by DCs infected with either MVA-OVA P7.5 or MVA-OVA mPH5 was only marginally affected at the highest MOI (Figure 3), particularly in cells infected by MVA-OVA mPH5. The expression of MHC class II (Supplementary Figure S1) followed a decreasing trend similar to MHC class I, whereas expression of CD86 and CD80 showed increasing levels with MOI (Supplementary Figure S2).


Gene Expression Driven by a Strong Viral Promoter in MVA Increases Vaccination Efficiency by Enhancing Antibody Responses and Unmasking CD8⁺ T Cell Epitopes.

Becker PD, Nörder M, Weissmann S, Ljapoci R, Erfle V, Drexler I, Guzmán CA - Vaccines (Basel) (2014)

DC expression of MHC class I depends on the MOI of MVA. DCs were infected with nrMVA, MVA-OVA P7.5, and MVA-OVA mPH5 at different MOIs for 6 h. After washing and further incubation for 16 h, changes in the expression of MHC class I were measured by flow cytometry. The MOIs of 0.05, 0.5, and 5 were arbitrarily considered as representative of low, intermediate, and high MOI, respectively (open histograms). Mock infected DCs (MVA = 0, shaded histogram) were considered as a basal level of MHC class I expression. Numbers in the upper right corners indicate fold-changes as %.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4494220&req=5

vaccines-02-00581-f003: DC expression of MHC class I depends on the MOI of MVA. DCs were infected with nrMVA, MVA-OVA P7.5, and MVA-OVA mPH5 at different MOIs for 6 h. After washing and further incubation for 16 h, changes in the expression of MHC class I were measured by flow cytometry. The MOIs of 0.05, 0.5, and 5 were arbitrarily considered as representative of low, intermediate, and high MOI, respectively (open histograms). Mock infected DCs (MVA = 0, shaded histogram) were considered as a basal level of MHC class I expression. Numbers in the upper right corners indicate fold-changes as %.
Mentions: It has been previously reported that nrMVA induces down-regulation of MHC class I expression. As expected, DCs infected with nrMVA showed a drastic decrease in the expression of MHC class I in a MOI-dependent manner. However, MHC class I expression by DCs infected with either MVA-OVA P7.5 or MVA-OVA mPH5 was only marginally affected at the highest MOI (Figure 3), particularly in cells infected by MVA-OVA mPH5. The expression of MHC class II (Supplementary Figure S1) followed a decreasing trend similar to MHC class I, whereas expression of CD86 and CD80 showed increasing levels with MOI (Supplementary Figure S2).

Bottom Line: T cells recognizing determinants derived from late viral proteins have a clear disadvantage to proliferate during secondary responses.Although the Ag-expression from the natural promoter 7.5 (P7.5) and the mPH5 seemed similar, detailed analysis showed that mPH5 not only induces higher expression levels than P7.5 during early phase of infection, but also Ag turnover is enhanced.The strong overexpression during the early phase leads to broader CD8 T cell responses, while preserving the priming efficiency of stable Ags.

View Article: PubMed Central - PubMed

Affiliation: Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, D-38124 Braunschweig, Germany. pablo.becker@kcl.ac.uk.

ABSTRACT
Viral vectors are promising tools for vaccination strategies and immunotherapies. However, CD8⁺ T cell responses against pathogen-derived epitopes are usually limited to dominant epitopes and antibody responses to recombinant encoded antigens (Ags) are mostly weak. We have previously demonstrated that the timing of viral Ag expression in infected professional Ag-presenting cells strongly shapes the epitope immunodominance hierarchy. T cells recognizing determinants derived from late viral proteins have a clear disadvantage to proliferate during secondary responses. In this work we evaluate the effect of overexpressing the recombinant Ag using the modified vaccinia virus early/late promoter H5 (mPH5). Although the Ag-expression from the natural promoter 7.5 (P7.5) and the mPH5 seemed similar, detailed analysis showed that mPH5 not only induces higher expression levels than P7.5 during early phase of infection, but also Ag turnover is enhanced. The strong overexpression during the early phase leads to broader CD8 T cell responses, while preserving the priming efficiency of stable Ags. Moreover, the increase in Ag-secretion favors the induction of strong antibody responses. Our findings provide the rationale to develop new strategies for fine-tuning the responses elicited by recombinant modified vaccinia virus Ankara by using selected promoters to improve the performance of this viral vector.

No MeSH data available.


Related in: MedlinePlus