The requirement for potent adjuvants to enhance the immunogenicity and protective efficacy of protein vaccines can be overcome by prior immunization with a recombinant adenovirus - PubMed (original) (raw)

The requirement for potent adjuvants to enhance the immunogenicity and protective efficacy of protein vaccines can be overcome by prior immunization with a recombinant adenovirus

Simone C de Cassan et al. J Immunol. 2011.

Abstract

A central goal in vaccinology is the induction of high and sustained Ab responses. Protein-in-adjuvant formulations are commonly used to achieve such responses. However, their clinical development can be limited by the reactogenicity of some of the most potent preclinical adjuvants and the cost and complexity of licensing new adjuvants for human use. Also, few adjuvants induce strong cellular immunity, which is important for protection against many diseases, such as malaria. We compared classical adjuvants such as aluminum hydroxide to new preclinical adjuvants and adjuvants in clinical development, such as Abisco 100, CoVaccine HT, Montanide ISA720, and stable emulsion-glucopyranosyl lipid A, for their ability to induce high and sustained Ab responses and T cell responses. These adjuvants induced a broad range of Ab responses when used in a three-shot protein-in-adjuvant regimen using the model Ag OVA and leading blood-stage malaria vaccine candidate Ags. Surprisingly, this range of Ab immunogenicity was greatly reduced when a protein-in-adjuvant vaccine was used to boost Ab responses primed by a human adenovirus serotype 5 vaccine recombinant for the same Ag. This human adenovirus serotype 5-protein regimen also induced a more cytophilic Ab response and demonstrated improved efficacy of merozoite surface protein-1 protein vaccines against a Plasmodium yoelii blood-stage challenge. This indicates that the differential immunogenicity of protein vaccine adjuvants may be largely overcome by prior immunization with recombinant adenovirus, especially for adjuvants that are traditionally considered poorly immunogenic in the context of subunit vaccination and may circumvent the need for more potent chemical adjuvants.

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Figures

Figure 1. Novel adjuvants can improve the immunogenicity of protein vaccines

C57BL/6 mice (_n_= 6 / group) were immunized i.m. with 20μg of OVA formulated in adjuvant. Total IgG titers were measured in the serum in response to OVA protein by ELISA. (A) IgG titers measured two weeks after each immunization (Imx). Median responses are shown with range. ** p<0.01 by two-way ANOVA with Bonferroni’s multiple comparison post-test. (B) IgG titers measured two weeks after the third immunization. Median responses are shown. T cell responses were assayed in the blood against the (C) pooled H-2b CD4+ T cell epitopes and (D) the H-2b CD8+ T cell epitope present in OVA. Median responses are shown. The dotted line indicates the threshold for responses above background in (A) and (B).

Figure 2. A priming immunization with a recombinant adenoviral vector reduces the differential antibody immunogenicity of protein-in-adjuvant vaccines

C57BL/6 mice (_n_= 6 / group) were primed i.m. with 1×1010 vp of AdHu5-OVA and boosted eight weeks later i.m. with OVA formulated in adjuvant. IgG titers were measured in the serum in response to OVA protein by ELISA. (A) IgG titers measured every two weeks after AdHu5-OVA. Median responses are shown after each immunization. (B) IgG titers measured eight weeks after the AdHu5-OVA prime ([Image: see text] pre-boost) and two weeks after the protein vaccine boost ([Image: see text] post-boost). Median responses are shown with range. (C) IgG titers measured two weeks after the protein vaccine. Median responses are shown with individual data points. T cell responses were assayed in the blood against the (D) pooled H-2b CD4+ T cell epitopes and (E) the H-2bCD8+ T cell epitope present in OVA. Median responses are shown. The dotted line indicates the threshold for responses above background in (A) – (C).

Figure 3. The effect of an adenoviral prime is consistent in other mouse strains and with other antigens

BALB/c mice (_n_=5 / group) were immunized twice i.m. three weeks apart with a mixture of 10μg of P. falciparum EBA-175 protein and 10μg of P. falciparum MSP-119 protein. IgG titers were measured in the serum to (A) EBA-175 protein two weeks after each immunization (Imx). Median responses are shown with range. IgG titers were measured in the serum in response to (B) EBA-175 protein and (C) MSP-119(QKNG allele) protein two weeks after the final immunization. Median responses are shown. BALB/c mice were primed i.m. with a mixture of 1×109 vp of AdHu5-MSP-1and AdHu5-EBA-175 and boosted i.m. eight weeks later with a mixture of 10μg of P. falciparum EBA-175 protein and 10μg of P. falciparum MSP-119 protein. IgG titers were measured in the serum in response to (D) EBA-175 protein and (E) MSP-119 (QKNG) protein eight weeks after the prime ([Image: see text] pre-boost) and two weeks after the protein vaccine boost ([Image: see text] post-boost). Median responses are shown with range. * p<0.05by one-way ANOVA with Bonferroni’s multiple comparison post-test. ***p<0.001 by two-way ANOVAwith Bonferroni’s multiple comparison post-test.

Figure 4. Longevity of vaccine-induced IgG responses

BALB/c and C57BL/6 mice (_n_=5-6 / group) were immunized as described previously. IgG titers were measured in the serum ten weeks after the final immunization in response to OVA protein in mice immunized with (A) AP regimes and (B) PPP regimes. Median responses are shown. (C) The reduction in log titers was calculated from IgG titers two weeks post the final immunization in each regime and IgG titers ten weeks after the final immunization. ** p<0.01, *** p<0.001 by two-way ANOVA with Bonferroni’s multiple comparison post-test. Median responses are shown with range. Antibody secreting cells (ASC) per 107 cells in mice immunized with AP regimes were quantified in the (D) bone marrow and (E) spleen ten weeks after the last immunization in response to MSP-119 protein. * p<0.05 by Kruskal-Wallis test with Dunn’s multiple comparison post-test. Median responses are shown. (F) IgG titers two weeks after the last immunization were correlated with antibody secreting cells in the spleen (■) and bone marrow(•) to MSP-119 protein for AP regimes. Spearman’s rank correlation co-efficient is shown. The dotted line indicates the threshold for responses above background in (A) and (B). ND = no data.

Figure 5. An adenoviral prime skews adjuvants towards the induction of cytophilic antibody isotypes

BALB/c and C57BL/6 mice (_n_=5-6 / group) were immunized as described previously with AP and PPP regimes. IgG1 and IgG2a antibody responses were measured in the serum two weeks after the last immunization in response to (A) OVA, (B) EBA-175 and (C) MSP-119(QKNG allele) protein. Median and individualresponses are shown (A-C). IgG2a:IgG1 ratios were calculated for (D) OVA and (E) EBA-175 and log transformed. Mean responses are shown (D-E). The dotted line indicates the threshold for responses above background in (A). ND = no data.

Figure 6. The effect of protein dose and immunization interval on antibody responses

C57BL/6 mice (_n_=5 / group) were immunized twice i.m. with 5μg or 20μg of OVA protein eight weeks (•) apart or with 20μg or 100μg of OVA two weeks (■)apart. Protein was formulated in (A) CoVaccine HT™, (B) SE+TLR4, (C) Adju-Phos® and (D) Abisco®100.In (C) C57BL/6 mice were also immunized with 20μg of OVA in CoVaccine HT™ and boosted eight weeks later with 20μg of OVA in Adju-Phos® (C_A ▲). IgG titers were measured in the serum two weeks after the final immunization. * p=0.0091 and ** p=0.0027 by t-test. Median responses are shown. The dotted line indicates the threshold for responses above background.

Figure 7. An adenoviral prime improves efficacy of MSP-1 protein vaccines following P. yoelii blood-stage challenge

BALB/c mice (_n_= 3-6 / group) were immunized i.m. with either i) 1.5 μg of P. yoelii MSP-119-GSTprotein in Adju-Phos® or CoVaccine HT™or PBS three weeks apart (PPP); or ii) primed with 1×1010 vp of AdHu5 MSP-142 and either not boosted (Ad only) or boosted eight weeks later with 1.5 μg of P. yoelii MSP-1-GSTprotein in Adju-Phos® or CoVaccine HT™ 19 (AP). IgG titers were measured in the serum in response to (A) P. yoelii MSP-119-IMX108 protein two weeks after the final immunization (day before challenge). * p<0.05 by one-way ANOVA with Bonferroni’s multiple comparison post-test. Median responses are shown. Mice were challenged with 105 pRBCs i.v. and parasitemia was measured as the percentage of infected red blood cells over time. Results are shown in (B) for the naïve unimmunized, Ad only and PPP PBS control groups as well as the PPP Adju-Phos® group; (C) mice immunized with PPP in CoVaccine HT™; (D) mice immunized with AP Adju-Phos®; and (E) mice immunized with AP CoVaccine HT™. Crosses indicate when mice were sacrificed. (F) AUC analysis of parasitemia. * p<0.05 by one-way ANOVA with Bonferroni’s multiple comparison post-test. Median responses are shown. (G) IgG titers measured two weeks after the final immunization in each regime were correlated with percentage peak parasitemia. Spearman’s rank correlation is shown. The dotted line indicates the threshold for responses above background in (A).

Figure 8. Improved efficacy of AP regimes following P. yoelii blood-stage challenge is not CD4+ T cell dependent

BALB/c mice (n = 6 / group) were immunized i.m. with either 1.5 μg of P. yoelii MSP-119-GSTprotein in Adju-Phos® three weeks apart (PPP), or primed with 1 × 1010 vp of AdHu5-PyMSP-142 (Ad42) and boosted eight weeks later with 1.5 μg of P. yoelii MSP-119-GSTprotein in Adju-Phos®. One group of mice immunized with the AP Adju-Phos® regime was depleted of CD4+ T cells, the other received normal rat IgG as a control. Separately BALB/c mice (n = 6 / group) were primed i.m. with 1 × 1010 vp of AdHu5-PyMSP-133 (Ad33) and boosted with three shots of 1.5 μg of P. yoelii MSP-119-GSTprotein in Adju-Phos® three weeks apart. All mice were challenged with 105 pRBCs i.v. two weeks after the final immunization and parasitemia was measured as the percentage of infected red blood cells over time. (A) The percentage of CD8+ IFN-γ+ T cells was measured by ICS in the PBMC of mice two weeks after the AdHu5 vaccines. Median responses are shown. (B) Representative flow plots from one depleted and control mouse showing the percentage of single and double CD3+ CD4+ and CD3+ CD8+ positive cells. (C) AUC analysis of parasitemia. * p<0.05 by one-way ANOVA with Bonferroni’s multiple comparison post-test. Median and individual responses are shown.

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The requirement for potent adjuvants to enhance the immunogenicity and protective efficacy of protein vaccines can be overcome by prior immunization with a recombinant adenovirus - PubMed (original) (raw)