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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

OVA-specific IgG1/IgG2c in sera of mice vaccinated with MVA-OVA P7.5 and MVA-OVA mPH5. OVA-specific IgG1 and IgG2c isotypes were determined by ELISA. Each bar represents the group mean end-point titre, the SEM is indicated by vertical lines. The results were statistically significant at p < 0.001 (***) compared to all groups.
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vaccines-02-00581-f006: OVA-specific IgG1/IgG2c in sera of mice vaccinated with MVA-OVA P7.5 and MVA-OVA mPH5. OVA-specific IgG1 and IgG2c isotypes were determined by ELISA. Each bar represents the group mean end-point titre, the SEM is indicated by vertical lines. The results were statistically significant at p < 0.001 (***) compared to all groups.

Mentions: In vitro results showed that the use of MVA-OVA mPH5 leads to a higher Ag production and induces higher numbers of IFN-γ producing CD4+ T cells than MVA-OVA P7.5. Thus, we investigated if these constructs would induce different immune responses in an in vivo model. Mice were immunized by i.m. route with MVA-OVA P7.5 or MVA-OVA mPH5 twice (day 0 and 28), and the immune responses elicited were then evaluated. As controls, mice were immunized with either PBS or nrMVA. Immunization with MVA-OVA P7.5 induced only a moderate OVA specific IgG response, whereas immunization with MVA-OVA mPH5 induced a strong OVA-specific IgG response (Figure 6) that is comparable to responses elicited in mice immunized with OVA protein using nrMVA as adjuvant [30]. Conversely to IgG responses, in mice immunized with nrMVA + OVA and MVA-OVA P7.5, MVA-OVA mPH5 IgG responses were characterized by a significantly enhanced production of IgG2c (Figure 6). This in turn indicates stimulation of a dominant Th1 response.


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)

OVA-specific IgG1/IgG2c in sera of mice vaccinated with MVA-OVA P7.5 and MVA-OVA mPH5. OVA-specific IgG1 and IgG2c isotypes were determined by ELISA. Each bar represents the group mean end-point titre, the SEM is indicated by vertical lines. The results were statistically significant at p < 0.001 (***) compared to all groups.
© Copyright Policy
Related In: Results  -  Collection

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

vaccines-02-00581-f006: OVA-specific IgG1/IgG2c in sera of mice vaccinated with MVA-OVA P7.5 and MVA-OVA mPH5. OVA-specific IgG1 and IgG2c isotypes were determined by ELISA. Each bar represents the group mean end-point titre, the SEM is indicated by vertical lines. The results were statistically significant at p < 0.001 (***) compared to all groups.
Mentions: In vitro results showed that the use of MVA-OVA mPH5 leads to a higher Ag production and induces higher numbers of IFN-γ producing CD4+ T cells than MVA-OVA P7.5. Thus, we investigated if these constructs would induce different immune responses in an in vivo model. Mice were immunized by i.m. route with MVA-OVA P7.5 or MVA-OVA mPH5 twice (day 0 and 28), and the immune responses elicited were then evaluated. As controls, mice were immunized with either PBS or nrMVA. Immunization with MVA-OVA P7.5 induced only a moderate OVA specific IgG response, whereas immunization with MVA-OVA mPH5 induced a strong OVA-specific IgG response (Figure 6) that is comparable to responses elicited in mice immunized with OVA protein using nrMVA as adjuvant [30]. Conversely to IgG responses, in mice immunized with nrMVA + OVA and MVA-OVA P7.5, MVA-OVA mPH5 IgG responses were characterized by a significantly enhanced production of IgG2c (Figure 6). This in turn indicates stimulation of a dominant Th1 response.

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