Limits...
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

IFN-γ-producing cells in mice vaccinated with MVA-OVA P7.5 and MVA-OVA mPH5. Splenocytes of immunized mice were re-stimulated in vitro for 16 h with peptides encompassing the dominant (SIINFEKL) and subdominants (KVVRFDKL and CFDVFKL) MHC class I restricted epitopes of OVA to determine the number of IFN-γ secreting CD8+ T cells. Results are presented as specific spot forming units (SFU)/1 × 106 cells. The SEM of quadruplicate values is indicated by vertical lines. The values reported are those obtained from stimulated cells with the background from non-stimulated cells being subtracted. The results were statistically significant at p < 0.001 (***).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4494220&req=5

vaccines-02-00581-f007: IFN-γ-producing cells in mice vaccinated with MVA-OVA P7.5 and MVA-OVA mPH5. Splenocytes of immunized mice were re-stimulated in vitro for 16 h with peptides encompassing the dominant (SIINFEKL) and subdominants (KVVRFDKL and CFDVFKL) MHC class I restricted epitopes of OVA to determine the number of IFN-γ secreting CD8+ T cells. Results are presented as specific spot forming units (SFU)/1 × 106 cells. The SEM of quadruplicate values is indicated by vertical lines. The values reported are those obtained from stimulated cells with the background from non-stimulated cells being subtracted. The results were statistically significant at p < 0.001 (***).

Mentions: We then evaluated the induction of Ag-specific CD8+ T cells by vaccination with the two rMVA viruses. To this end, we first assessed the number of Ag specific IFN-γ secreting CD8+ T cells by intracellular staining when splenocytes were re-stimulated ex vivo with a peptide corresponding to the dominant OVA epitope (SIINFEKL). Immunization with both rMVAs expressing OVA resulted in the induction of high numbers of IFN-γ producing CD8+ T cells in response to the immune dominant peptide (Supplementary Figure S4). These results were confirmed in an independent experiment by ELISPOT (p < 0.001, Figure 7).


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)

IFN-γ-producing cells in mice vaccinated with MVA-OVA P7.5 and MVA-OVA mPH5. Splenocytes of immunized mice were re-stimulated in vitro for 16 h with peptides encompassing the dominant (SIINFEKL) and subdominants (KVVRFDKL and CFDVFKL) MHC class I restricted epitopes of OVA to determine the number of IFN-γ secreting CD8+ T cells. Results are presented as specific spot forming units (SFU)/1 × 106 cells. The SEM of quadruplicate values is indicated by vertical lines. The values reported are those obtained from stimulated cells with the background from non-stimulated cells being subtracted. The results were statistically significant at p < 0.001 (***).
© Copyright Policy
Related In: Results  -  Collection

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

vaccines-02-00581-f007: IFN-γ-producing cells in mice vaccinated with MVA-OVA P7.5 and MVA-OVA mPH5. Splenocytes of immunized mice were re-stimulated in vitro for 16 h with peptides encompassing the dominant (SIINFEKL) and subdominants (KVVRFDKL and CFDVFKL) MHC class I restricted epitopes of OVA to determine the number of IFN-γ secreting CD8+ T cells. Results are presented as specific spot forming units (SFU)/1 × 106 cells. The SEM of quadruplicate values is indicated by vertical lines. The values reported are those obtained from stimulated cells with the background from non-stimulated cells being subtracted. The results were statistically significant at p < 0.001 (***).
Mentions: We then evaluated the induction of Ag-specific CD8+ T cells by vaccination with the two rMVA viruses. To this end, we first assessed the number of Ag specific IFN-γ secreting CD8+ T cells by intracellular staining when splenocytes were re-stimulated ex vivo with a peptide corresponding to the dominant OVA epitope (SIINFEKL). Immunization with both rMVAs expressing OVA resulted in the induction of high numbers of IFN-γ producing CD8+ T cells in response to the immune dominant peptide (Supplementary Figure S4). These results were confirmed in an independent experiment by ELISPOT (p < 0.001, Figure 7).

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