Limits...
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.

Show MeSH

Related in: MedlinePlus

Immunogenicity of MVAΔC12L in BALB/c mice.Groups of four BALB/c mice were i.p immunized with 5×107 pfu of MVAwt (white bars) or MVAΔC12L (black bars), and seven dpi specific-CD8+ T-cell responses against the E3 and F2(G) VACV peptides were evaluated in the spleen. (A) The magnitude of the specific responses was measured by IFN-γ (left) and IL-2 (right) Elispot assays. Background (RPMI negative control) subtracted results are depicted as mean spot forming units (SFU) per 106 splenocytes ± SD. (B) Quality of the response analyzed by ICS. Degranulation of specific-CD8+ T-cells was assessed with CD107a/b mAb (cytotoxicity marker) simultaneously with IFN-γ production, after 5 hr of stimulation with VACV peptides Results are expressed as mean % CD8+ T-cells ± SD. Statistically significant differences: *p<0.05, **p<0.01.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3285208&req=5

pone-0032220-g002: Immunogenicity of MVAΔC12L in BALB/c mice.Groups of four BALB/c mice were i.p immunized with 5×107 pfu of MVAwt (white bars) or MVAΔC12L (black bars), and seven dpi specific-CD8+ T-cell responses against the E3 and F2(G) VACV peptides were evaluated in the spleen. (A) The magnitude of the specific responses was measured by IFN-γ (left) and IL-2 (right) Elispot assays. Background (RPMI negative control) subtracted results are depicted as mean spot forming units (SFU) per 106 splenocytes ± SD. (B) Quality of the response analyzed by ICS. Degranulation of specific-CD8+ T-cells was assessed with CD107a/b mAb (cytotoxicity marker) simultaneously with IFN-γ production, after 5 hr of stimulation with VACV peptides Results are expressed as mean % CD8+ T-cells ± SD. Statistically significant differences: *p<0.05, **p<0.01.

Mentions: After the corroboration of the depletion of the IL-18 bp activity from the MVA mutant generated, our next aim was to analyze the modulation of IL-18 bp during the final adaptive immune response generated against the viral vector antigens. To achieve this aim, we firstly analyzed the modulation effects induced after mice inoculation with a high dose of the virus (5×107 pfu) by intraperitoneal (i.p) route. The specific cellular immune response was analyzed 7 days after inoculation, during the acute phase of the response. Figure 2 describes the results found in BALB/c mice (H-2d). The specific anti-vector immunogenicity was evaluated against the Vaccinia E3 and F2(G) CD8+ T-cell epitopes previously defined. Both epitopes are located on proteins that are expressed early during virus infection [28], similarly to the IL-18 bp product which is expressed before viral DNA replication. Therefore, if the inhibition of the host IL-18 effect mediated by the viral IL-18 bp is causing a depression of the final anti-viral cellular immune response this would be expected to be reflected in the response against these epitopes. Figure 2A (left panel) describes the specific cellular immune response (IFN-γ secreting cells) against the E3 and F2(G) peptides found in the spleen of mice from both groups, where it is shown that for those MVAΔC12L inoculated, significant increments (p<0,01) (2 and 2,5 fold against E3 and F2(G) peptides respectively) were found. Even more, a significant increment was also observed when the IL-2 response was analyzed (Fig. 2A right panel). Thus, after the results obtained by Elispot we did a more in depth analysis by flow cytometry, restimulating the cells for 5 hours with the specific stimulus. We corroborated the results found by Elispot for IFN-γ, but most importantly we could also determine that the immunization with MVAΔC12L also generated an increment in the cytotoxic activity (degranulation evaluated by positive CD107a/b staining), which resulted significantly different for the E3 peptide (p<0,05) (Fig. 2B, right panel).


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 BALB/c mice.Groups of four BALB/c mice were i.p immunized with 5×107 pfu of MVAwt (white bars) or MVAΔC12L (black bars), and seven dpi specific-CD8+ T-cell responses against the E3 and F2(G) VACV peptides were evaluated in the spleen. (A) The magnitude of the specific responses was measured by IFN-γ (left) and IL-2 (right) Elispot assays. Background (RPMI negative control) subtracted results are depicted as mean spot forming units (SFU) per 106 splenocytes ± SD. (B) Quality of the response analyzed by ICS. Degranulation of specific-CD8+ T-cells was assessed with CD107a/b mAb (cytotoxicity marker) simultaneously with IFN-γ production, after 5 hr of stimulation with VACV peptides Results are expressed as mean % CD8+ T-cells ± SD. Statistically significant differences: *p<0.05, **p<0.01.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285208&req=5

pone-0032220-g002: Immunogenicity of MVAΔC12L in BALB/c mice.Groups of four BALB/c mice were i.p immunized with 5×107 pfu of MVAwt (white bars) or MVAΔC12L (black bars), and seven dpi specific-CD8+ T-cell responses against the E3 and F2(G) VACV peptides were evaluated in the spleen. (A) The magnitude of the specific responses was measured by IFN-γ (left) and IL-2 (right) Elispot assays. Background (RPMI negative control) subtracted results are depicted as mean spot forming units (SFU) per 106 splenocytes ± SD. (B) Quality of the response analyzed by ICS. Degranulation of specific-CD8+ T-cells was assessed with CD107a/b mAb (cytotoxicity marker) simultaneously with IFN-γ production, after 5 hr of stimulation with VACV peptides Results are expressed as mean % CD8+ T-cells ± SD. Statistically significant differences: *p<0.05, **p<0.01.
Mentions: After the corroboration of the depletion of the IL-18 bp activity from the MVA mutant generated, our next aim was to analyze the modulation of IL-18 bp during the final adaptive immune response generated against the viral vector antigens. To achieve this aim, we firstly analyzed the modulation effects induced after mice inoculation with a high dose of the virus (5×107 pfu) by intraperitoneal (i.p) route. The specific cellular immune response was analyzed 7 days after inoculation, during the acute phase of the response. Figure 2 describes the results found in BALB/c mice (H-2d). The specific anti-vector immunogenicity was evaluated against the Vaccinia E3 and F2(G) CD8+ T-cell epitopes previously defined. Both epitopes are located on proteins that are expressed early during virus infection [28], similarly to the IL-18 bp product which is expressed before viral DNA replication. Therefore, if the inhibition of the host IL-18 effect mediated by the viral IL-18 bp is causing a depression of the final anti-viral cellular immune response this would be expected to be reflected in the response against these epitopes. Figure 2A (left panel) describes the specific cellular immune response (IFN-γ secreting cells) against the E3 and F2(G) peptides found in the spleen of mice from both groups, where it is shown that for those MVAΔC12L inoculated, significant increments (p<0,01) (2 and 2,5 fold against E3 and F2(G) peptides respectively) were found. Even more, a significant increment was also observed when the IL-2 response was analyzed (Fig. 2A right panel). Thus, after the results obtained by Elispot we did a more in depth analysis by flow cytometry, restimulating the cells for 5 hours with the specific stimulus. We corroborated the results found by Elispot for IFN-γ, but most importantly we could also determine that the immunization with MVAΔC12L also generated an increment in the cytotoxic activity (degranulation evaluated by positive CD107a/b staining), which resulted significantly different for the E3 peptide (p<0,05) (Fig. 2B, right panel).

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