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Combination of E- and NS1-Derived DNA Vaccines: The Immune Response and Protection Elicited in Mice against DENV2.

ABSTRACT: The occurrence of dengue disease has increased radically in recent decades. Previously, we constructed the pE1D2 and pcTPANS1 DNA vaccines encoding the DENV2 envelope (E) and non-structural 1 (NS1) proteins, respectively. To decrease the number of plasmids in a tetravalent candidate vaccine, we constructed a bicistronic plasmid, pNS1/E/D2, encoding these two proteins simultaneously. We evaluated the protective immunity induced in mice vaccinated with the pNS1/E/D2 candidate and compared to the responses elicited by immunization with the former vaccines isolated or in combination. We transfected BHK-21 cells with the different plasmids and detected recombinant proteins by immunofluorescence and mass spectrometry assays to confirm antigen expression. BALB/c mice were inoculated with the DNA vaccines followed by a lethal DENV2 challenge. ELISA, PRNT50, and IFN-gamma ELISPOT assays were performed for the investigation of the humoral and cellular responses. We observed the concomitant expression of NS1 and E proteins in pNS1/E/D2-transfected cells. All E-based vaccines induced anti-E and neutralizing antibodies. However, anti-NS1 antibodies were only observed after immunization with the pcTPANS1 administered alone or combined with pE1D2. In contrast, splenocytes from pNS1/E/D2- or pcTPANS1 + pE1D2-vaccinated animals responded to NS1- and E-derived synthetic peptides. All the DNA vaccines conferred protection against DENV2.

SUBMITTER: Pinto PBA

PROVIDER: S-EPMC9323404 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Combination of E- and NS1-Derived DNA Vaccines: The Immune Response and Protection Elicited in Mice against DENV2.

Pinto Paolla Beatriz A PBA Barros Tamiris A C TAC Lima Lauro M LM Pacheco Agatha R AR Assis Maysa L ML Pereira Bernardo A S BAS Gonçalves Antônio J S AJS Azevedo Adriana S AS Neves-Ferreira Ana Gisele C AGC Costa Simone M SM Alves Ada M B AMB

Viruses 20220630 7

The occurrence of dengue disease has increased radically in recent decades. Previously, we constructed the pE1D2 and pcTPANS1 DNA vaccines encoding the DENV2 envelope (E) and non-structural 1 (NS1) proteins, respectively. To decrease the number of plasmids in a tetravalent candidate vaccine, we constructed a bicistronic plasmid, pNS1/E/D2, encoding these two proteins simultaneously. We evaluated the protective immunity induced in mice vaccinated with the pNS1/E/D2 candidate and compared to the r ...[more]

PMID: 35891431

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Project description:The importance of the cellular immune response against DENV has been increasingly highlighted in the past few years, in particular for vaccine development. We have previously constructed two plasmids, pE1D2, and pcTPANS1, encoding the envelope (E) ectodomain (domains I, II, and III) and the non-structural 1 (NS1) protein of dengue virus serotype 2 (DENV2), respectively. In the present work, we analyzed the induction of the cellular response in mice immunized with these DNA vaccines and identified the immunogenic peptides. Vaccinated BALB/c mice became protected against a lethal challenge of DENV2. Depletion of CD4+ cells in vaccinated animals almost completely abolished protection elicited by both vaccines. In contrast, a significant number of pE1D2- and pcTPANS1-immunized mice survived virus challenge after depletion of CD8+ cells, although some animals presented morbidity. To identify immunogenic peptides recognized by T cells, we stimulated splenocytes with overlapping peptide libraries covering the E and NS1 proteins and evaluated the production of IFN-γ by ELISPOT. We detected two and three immunodominant epitopes in the E and NS1 proteins, respectively, and four additional NS1-derived peptides after virus challenge. Characterization by intracellular cytokine staining (ICS) revealed that both CD4+ and CD8+ T cells were involved in IFN-γ and TNF-α production. The IFN-γ ICS confirmed reaction of almost all E-derived peptides before challenge and identified other epitopes after infection. All NS1-derived peptides were able to elicit IFN-γ production in CD4+ cells, while only a few peptides induced expression of this cytokine in CD8+ T lymphocytes. Interestingly, we observed an increase in the frequency of either CD4+ or CD8+ T cells producing TNF-α after immunization with the pE1D2 and challenge with DENV2, while lymphocytes from pcTPANS1-vaccinated animals maintained ordinary TNF-α production after virus infection. We also assessed the recognition of E and NS1 immunogenic peptides in C57BL/6 mice due to the difference in MHC haplotype expression. Two NS1-derived epitopes featured prominently in the IFN-γ response with cells from both animal strains. Overall, our results emphasize the importance of the T cell response involved in protection against dengue induced by E and NS1 based DNA vaccines.

Project description:Zika virus is a mosquito-borne flavivirus which can cause severe disease in humans, including microcephaly and other congenital malformations in newborns and Guillain-Barré syndrome in adults. There are currently no approved prophylactics or therapeutics for Zika virus; the development of a safe and effective vaccine is an urgent priority. Preclinical studies suggest that the envelope glycoprotein can elicit potently neutralizing antibodies. However, such antibodies are implicated in the phenomenon of antibody-dependent enhancement of disease. We have previously shown that monoclonal antibodies targeting the Zika virus nonstructural NS1 protein are protective without inducing antibody-dependent enhancement of disease. Here, we investigated whether the NS1 protein itself is a viable vaccine target. Wild-type mice were vaccinated with an NS1-expressing DNA plasmid followed by two adjuvanted protein boosters, which elicited high antibody titers. Passive transfer of the immune sera was able to significantly protect STAT2 knockout mice against lethal challenge by Zika virus. In addition, long-lasting NS1-specific IgG responses were detected in serum samples from patients in either the acute or the convalescent phase of Zika virus infection. These NS1-specific antibodies were able to functionally engage Fcγ receptors. In contrast, envelope-specific antibodies did not activate Fc-mediated effector functions on infected cells. Our data suggest that the Zika virus NS1 protein, which is expressed on infected cells, is critical for Fc-dependent cell-mediated immunity. The present study demonstrates that the Zika virus NS1 protein is highly immunogenic and can elicit protective antibodies, underscoring its potential for an effective Zika virus vaccine.IMPORTANCE Zika virus is a global public health threat that causes microcephaly and congenital malformations in newborns and Guillain-Barré syndrome in adults. Currently, no vaccines or treatments are available. While antibodies targeting the envelope glycoprotein can neutralize virus, they carry the risk of antibody-dependent enhancement of disease (ADE). In contrast, antibodies generated against the NS1 protein can be protective without eliciting ADE. The present study demonstrates the effectiveness of an NS1-based vaccine in eliciting high titers of protective antibodies against Zika virus disease in a mouse model. Sera generated by this vaccine can elicit Fc-mediated effector functions against Zika virus-infected cells. Lastly, we provide human data suggesting that the antibody response against the Zika virus NS1 protein is long-lasting and functionally active. Overall, our work will inform the development of a safe and effective Zika virus vaccine.

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Dataset Information

Combination of E- and NS1-Derived DNA Vaccines: The Immune Response and Protection Elicited in Mice against DENV2.

Publications

Combination of E- and NS1-Derived DNA Vaccines: The Immune Response and Protection Elicited in Mice against DENV2.

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