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Improving the MVA vaccine potential by deleting the viral gene coding for the IL-18 binding protein.

Falivene J, Del Médico Zajac MP, Pascutti MF, Rodríguez AM, Maeto C, Perdiguero B, Gómez CE, Esteban M, Calamante G, Gherardi MM - PLoS ONE (2012)

Bottom Line: Of note, we could also show a significant increase in the CIR against HIV antigens such as Env, Gag, Pol and Nef from different subtypes expressed from two recombinants of MVAΔC12L during heterologous DNA prime/MVA boost vaccination regimens.This study demonstrates the relevance of IL-18 bp contribution in the immune response evasion during MVA infection.Our findings clearly show that the deletion of the viral IL-18 bp gene is an effective approach to increase MVA vaccine efficacy, as immunogenicity improvements were observed against vector antigens and more importantly to HIV antigens.

View Article: PubMed Central - PubMed

Affiliation: Centro Nacional de Referencia para el SIDA, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.

ABSTRACT

Background: Modified Vaccinia Ankara (MVA) is an attenuated strain of Vaccinia virus (VACV) currently employed in many clinical trials against HIV/AIDS and other diseases. MVA still retains genes involved in host immune response evasion, enabling its optimization by removing some of them. The aim of this study was to evaluate cellular immune responses (CIR) induced by an IL-18 binding protein gene (C12L) deleted vector (MVAΔC12L).

Methodology/principal findings: BALB/c and C57BL/6 mice were immunized with different doses of MVAΔC12L or MVA wild type (MVAwt), then CIR to VACV epitopes in immunogenic proteins were evaluated in spleen and draining lymph nodes at acute and memory phases (7 and 40 days post-immunization respectively). Compared with parental MVAwt, MVAΔC12L immunization induced a significant increase of two to three-fold in CD8(+) and CD4(+) T-cell responses to different VACV epitopes, with increased percentage of anti-VACV cytotoxic CD8(+) T-cells (CD107a/b(+)) during the acute phase of the response. Importantly, the immunogenicity enhancement was also observed after MVAΔC12L inoculation with different viral doses and by distinct routes (systemic and mucosal). Potentiation of MVA's CIR was also observed during the memory phase, in correlation with a higher protection against an intranasal challenge with VACV WR. Of note, we could also show a significant increase in the CIR against HIV antigens such as Env, Gag, Pol and Nef from different subtypes expressed from two recombinants of MVAΔC12L during heterologous DNA prime/MVA boost vaccination regimens.

Conclusions/significance: This study demonstrates the relevance of IL-18 bp contribution in the immune response evasion during MVA infection. Our findings clearly show that the deletion of the viral IL-18 bp gene is an effective approach to increase MVA vaccine efficacy, as immunogenicity improvements were observed against vector antigens and more importantly to HIV antigens.

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Immunogenicity of MVAΔC12L in C57BL/6 mice.Groups of four C57BL/6 mice were i.p vaccinated with 5×107 pfu of MVAwt (white bars) or MVAΔC12L (black bars) and seven dpi T-cell responses against VACV peptides B8R (CD8+-specific), E9L, H3L and L4R (CD4+-specific) were evaluated in the spleen. (A) The magnitude of the response was measured by IFN-γ Elispot assay after 24 hr stimulation. Background (RPMI negative control) subtracted results are depicted as mean IFN-γ spot forming units (SFU) per 106 splenocytes ± SD. (B) IFN-γ production in splenocyte-culture supernatants was evaluated by ELISA after 72 hr stimulation. (C) Quality of the response was analyzed by ICS. Degranulation of specific-CD8+ T-cells was assessed with CD107a/b mAb together with IFN-γ production, after 5 hr stimulation with the indicated peptides. Results are expressed as mean % of specific CD8+ T-cells ± SD. Statistically significant differences: *p<0.05, **p<0.01, ***p<0.001.
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pone-0032220-g003: Immunogenicity of MVAΔC12L in C57BL/6 mice.Groups of four C57BL/6 mice were i.p vaccinated with 5×107 pfu of MVAwt (white bars) or MVAΔC12L (black bars) and seven dpi T-cell responses against VACV peptides B8R (CD8+-specific), E9L, H3L and L4R (CD4+-specific) were evaluated in the spleen. (A) The magnitude of the response was measured by IFN-γ Elispot assay after 24 hr stimulation. Background (RPMI negative control) subtracted results are depicted as mean IFN-γ spot forming units (SFU) per 106 splenocytes ± SD. (B) IFN-γ production in splenocyte-culture supernatants was evaluated by ELISA after 72 hr stimulation. (C) Quality of the response was analyzed by ICS. Degranulation of specific-CD8+ T-cells was assessed with CD107a/b mAb together with IFN-γ production, after 5 hr stimulation with the indicated peptides. Results are expressed as mean % of specific CD8+ T-cells ± SD. Statistically significant differences: *p<0.05, **p<0.01, ***p<0.001.

Mentions: The Elispot analysis showed that in the case of the CD8+ epitope, the MVAΔC12L generated an increment of 3 to 4-fold (depending of the experiment) (Fig. 3A). It must be noted that the improved immune response, afforded by the mutant MVA in this mouse strain, was enhanced compared to the CD8+ T-cell responses studied in BALB/c. In relation to the CD4+ T-cell responses after MVAwt inoculation, the highest magnitude was detected against the E9L peptide (expressed early during viral replication) whereas minor responses were detected against the other two epitopes which were expressed at later times. Increments afforded by the MVA mutant against the CD4+ peptides (Fig. 3A) were of nearly two-fold in the IFN-γ secreting cells determined by Elispot after a restimulation period of 24 h, whereas extending this period to 72 h and quantifying levels of specific IFN-γ secreted, the differences between both vectors were pronounced (Fig. 3B). Thus, increments of 2.5 (H3L) to 3 fold (L4R) in relation to MVAwt induced responses were observed. Moreover, in this model we also evaluated if MVAΔC12L modulated the cytotoxicity of the CD8+ specific response, with the findings of a significant increase in B8R specific CD107a/b cells in those mice inoculated with the mutant MVA (Fig. 3C).


Improving the MVA vaccine potential by deleting the viral gene coding for the IL-18 binding protein.

Falivene J, Del Médico Zajac MP, Pascutti MF, Rodríguez AM, Maeto C, Perdiguero B, Gómez CE, Esteban M, Calamante G, Gherardi MM - PLoS ONE (2012)

Immunogenicity of MVAΔC12L in C57BL/6 mice.Groups of four C57BL/6 mice were i.p vaccinated with 5×107 pfu of MVAwt (white bars) or MVAΔC12L (black bars) and seven dpi T-cell responses against VACV peptides B8R (CD8+-specific), E9L, H3L and L4R (CD4+-specific) were evaluated in the spleen. (A) The magnitude of the response was measured by IFN-γ Elispot assay after 24 hr stimulation. Background (RPMI negative control) subtracted results are depicted as mean IFN-γ spot forming units (SFU) per 106 splenocytes ± SD. (B) IFN-γ production in splenocyte-culture supernatants was evaluated by ELISA after 72 hr stimulation. (C) Quality of the response was analyzed by ICS. Degranulation of specific-CD8+ T-cells was assessed with CD107a/b mAb together with IFN-γ production, after 5 hr stimulation with the indicated peptides. Results are expressed as mean % of specific CD8+ T-cells ± SD. Statistically significant differences: *p<0.05, **p<0.01, ***p<0.001.
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pone-0032220-g003: Immunogenicity of MVAΔC12L in C57BL/6 mice.Groups of four C57BL/6 mice were i.p vaccinated with 5×107 pfu of MVAwt (white bars) or MVAΔC12L (black bars) and seven dpi T-cell responses against VACV peptides B8R (CD8+-specific), E9L, H3L and L4R (CD4+-specific) were evaluated in the spleen. (A) The magnitude of the response was measured by IFN-γ Elispot assay after 24 hr stimulation. Background (RPMI negative control) subtracted results are depicted as mean IFN-γ spot forming units (SFU) per 106 splenocytes ± SD. (B) IFN-γ production in splenocyte-culture supernatants was evaluated by ELISA after 72 hr stimulation. (C) Quality of the response was analyzed by ICS. Degranulation of specific-CD8+ T-cells was assessed with CD107a/b mAb together with IFN-γ production, after 5 hr stimulation with the indicated peptides. Results are expressed as mean % of specific CD8+ T-cells ± SD. Statistically significant differences: *p<0.05, **p<0.01, ***p<0.001.
Mentions: The Elispot analysis showed that in the case of the CD8+ epitope, the MVAΔC12L generated an increment of 3 to 4-fold (depending of the experiment) (Fig. 3A). It must be noted that the improved immune response, afforded by the mutant MVA in this mouse strain, was enhanced compared to the CD8+ T-cell responses studied in BALB/c. In relation to the CD4+ T-cell responses after MVAwt inoculation, the highest magnitude was detected against the E9L peptide (expressed early during viral replication) whereas minor responses were detected against the other two epitopes which were expressed at later times. Increments afforded by the MVA mutant against the CD4+ peptides (Fig. 3A) were of nearly two-fold in the IFN-γ secreting cells determined by Elispot after a restimulation period of 24 h, whereas extending this period to 72 h and quantifying levels of specific IFN-γ secreted, the differences between both vectors were pronounced (Fig. 3B). Thus, increments of 2.5 (H3L) to 3 fold (L4R) in relation to MVAwt induced responses were observed. Moreover, in this model we also evaluated if MVAΔC12L modulated the cytotoxicity of the CD8+ specific response, with the findings of a significant increase in B8R specific CD107a/b cells in those mice inoculated with the mutant MVA (Fig. 3C).

Bottom Line: Of note, we could also show a significant increase in the CIR against HIV antigens such as Env, Gag, Pol and Nef from different subtypes expressed from two recombinants of MVAΔC12L during heterologous DNA prime/MVA boost vaccination regimens.This study demonstrates the relevance of IL-18 bp contribution in the immune response evasion during MVA infection.Our findings clearly show that the deletion of the viral IL-18 bp gene is an effective approach to increase MVA vaccine efficacy, as immunogenicity improvements were observed against vector antigens and more importantly to HIV antigens.

View Article: PubMed Central - PubMed

Affiliation: Centro Nacional de Referencia para el SIDA, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.

ABSTRACT

Background: Modified Vaccinia Ankara (MVA) is an attenuated strain of Vaccinia virus (VACV) currently employed in many clinical trials against HIV/AIDS and other diseases. MVA still retains genes involved in host immune response evasion, enabling its optimization by removing some of them. The aim of this study was to evaluate cellular immune responses (CIR) induced by an IL-18 binding protein gene (C12L) deleted vector (MVAΔC12L).

Methodology/principal findings: BALB/c and C57BL/6 mice were immunized with different doses of MVAΔC12L or MVA wild type (MVAwt), then CIR to VACV epitopes in immunogenic proteins were evaluated in spleen and draining lymph nodes at acute and memory phases (7 and 40 days post-immunization respectively). Compared with parental MVAwt, MVAΔC12L immunization induced a significant increase of two to three-fold in CD8(+) and CD4(+) T-cell responses to different VACV epitopes, with increased percentage of anti-VACV cytotoxic CD8(+) T-cells (CD107a/b(+)) during the acute phase of the response. Importantly, the immunogenicity enhancement was also observed after MVAΔC12L inoculation with different viral doses and by distinct routes (systemic and mucosal). Potentiation of MVA's CIR was also observed during the memory phase, in correlation with a higher protection against an intranasal challenge with VACV WR. Of note, we could also show a significant increase in the CIR against HIV antigens such as Env, Gag, Pol and Nef from different subtypes expressed from two recombinants of MVAΔC12L during heterologous DNA prime/MVA boost vaccination regimens.

Conclusions/significance: This study demonstrates the relevance of IL-18 bp contribution in the immune response evasion during MVA infection. Our findings clearly show that the deletion of the viral IL-18 bp gene is an effective approach to increase MVA vaccine efficacy, as immunogenicity improvements were observed against vector antigens and more importantly to HIV antigens.

Show MeSH
Related in: MedlinePlus