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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 CD86 expression 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 CD86 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) was considered as a basal level of CD86 expression. Numbers in the upper right corners indicate fold-changes as %.
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vaccines-02-00581-f002: DC CD86 expression 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 CD86 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) was considered as a basal level of CD86 expression. Numbers in the upper right corners indicate fold-changes as %.

Mentions: Murine bone marrow (BM)-derived DCs were infected with rMVA at different multiplicities of infection ([MOIs] 0.05, 0.5, and 5), which were in turn considered as low, intermediate and high. The DC activation status was first evaluated by assessing the expression of the co-stimulatory molecules CD80 and CD86. At all tested MOIs, the number of DCs expressing CD86 was higher compared to the non-infected DCs. As we previously reported [30], DCs infected with nrMVA showed a low expression of CD86 at the highest MOI (Figure 2). Cells infected with MVA-OVA P7.5 showed the highest level of CD86 expression at the intermediate MOI and a slightly lower level at the highest MOI. In contrast, DCs infected with MVA-OVA mPH5 showed lower levels of CD86 expression than DCs infected with the other MVAs at the lowest MOI. However, the expression of CD86 increased in a MOI-dependent manner (Figure 2). This suggests that the level of activation of DCs depends not only on the MOI but also on the Ag expression level.


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 CD86 expression 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 CD86 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) was considered as a basal level of CD86 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-f002: DC CD86 expression 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 CD86 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) was considered as a basal level of CD86 expression. Numbers in the upper right corners indicate fold-changes as %.
Mentions: Murine bone marrow (BM)-derived DCs were infected with rMVA at different multiplicities of infection ([MOIs] 0.05, 0.5, and 5), which were in turn considered as low, intermediate and high. The DC activation status was first evaluated by assessing the expression of the co-stimulatory molecules CD80 and CD86. At all tested MOIs, the number of DCs expressing CD86 was higher compared to the non-infected DCs. As we previously reported [30], DCs infected with nrMVA showed a low expression of CD86 at the highest MOI (Figure 2). Cells infected with MVA-OVA P7.5 showed the highest level of CD86 expression at the intermediate MOI and a slightly lower level at the highest MOI. In contrast, DCs infected with MVA-OVA mPH5 showed lower levels of CD86 expression than DCs infected with the other MVAs at the lowest MOI. However, the expression of CD86 increased in a MOI-dependent manner (Figure 2). This suggests that the level of activation of DCs depends not only on the MOI but also on the Ag expression level.

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