Adjuvant combination and antigen multimerization shape neutralizing antibody and T cell responses to a SARS-CoV-2 RBD subunit vaccine
IntroductionThe rapid development and deployment of multiple safe and effective COVID-19 vaccines were critical cornerstones of pandemic control. However, vaccine inequity and the emergence of new variants of concern (VOCs) highlighted major gaps in the global strategy to control SARS-CoV-2 infectio...
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Frontiers Media S.A.
2025-07-01
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| author | João Pedro da Silva Nunes Mariângela de Oliveira Silva Juliana de Souza Apostolico Isabela Pazotti Daher Rodolfo Ferreira Marques Marcio Massao Yamamoto Alexia Adrianne Venceslau Brito Carvalho Maria Fernanda de Castro-Amarante Edison Luiz Durigon Carsten Wrenger Luiz Mario Ramos Janini Edmarcia Elisa de Souza Robert Andreata-Santos Juliana Terzi Maricato Edecio Cunha-Neto Edecio Cunha-Neto Edecio Cunha-Neto Jorge Kalil Jorge Kalil Silvia Beatriz Boscardin Silvia Beatriz Boscardin Daniela Santoro Rosa Daniela Santoro Rosa |
| author_facet | João Pedro da Silva Nunes Mariângela de Oliveira Silva Juliana de Souza Apostolico Isabela Pazotti Daher Rodolfo Ferreira Marques Marcio Massao Yamamoto Alexia Adrianne Venceslau Brito Carvalho Maria Fernanda de Castro-Amarante Edison Luiz Durigon Carsten Wrenger Luiz Mario Ramos Janini Edmarcia Elisa de Souza Robert Andreata-Santos Juliana Terzi Maricato Edecio Cunha-Neto Edecio Cunha-Neto Edecio Cunha-Neto Jorge Kalil Jorge Kalil Silvia Beatriz Boscardin Silvia Beatriz Boscardin Daniela Santoro Rosa Daniela Santoro Rosa |
| author_sort | João Pedro da Silva Nunes |
| collection | DOAJ |
| description | IntroductionThe rapid development and deployment of multiple safe and effective COVID-19 vaccines were critical cornerstones of pandemic control. However, vaccine inequity and the emergence of new variants of concern (VOCs) highlighted major gaps in the global strategy to control SARS-CoV-2 infection. Despite the use of distinct platforms, most approved vaccines utilize the Spike protein as the main antigen due to its pivotal role in virus entry, mediated by the receptor binding domain (RBD). In this context, RBD stands out as a promising antigen for a subunit vaccine candidate, as it is the main target of neutralizing antibodies, has a well-established scalable production pipeline, and has proven safety. Approaches to enhance RBD immunogenicity encompass the addition of adjuvants and antigen multimerization. MethodsIn this study, we compared the immunogenic properties of the Wuhan RBD monomer and homodimer with an RBD heterotrimer formulation composed of the Delta, Beta and Gamma variants. We also screened different adjuvants to optimize both humoral and cellular immunity. ResultsOur results showed that immunization with the RBD dimer and trimer, in the presence of the adjuvant AddaS03, elicited a higher humoral response and a broader neutralization profile. Additionally, RBD-trimer immunization more efficiently inhibited viral replication in the lungs of mice challenged with the ancestral Wuhan strain compared to the monomer. We further optimized our vaccine formulation by combining the adjuvants AddaS03 and Poly I:C, which demonstrated a synergistic effect, integrating the potent humoral response induced by AddaS03 with the cellular Th1 skewing capacity of Poly I:C. The AddaS03+ Poly I:C mixture induced antibodies with higher affinity and an increased frequency of RBD-specific IgG2c-producing bone marrow plasma cells, highlighting the potential of this adjuvant combination to generate long-lived memory plasma cells. Additionally, we identified sequences within the RBD that induced specific IFNγ T cell responses. Peptide 12 (393-TNVYADSFVIRGDEVRQ-409) emerged as the immunodominant CD4 T cell epitope, whereas peptides 28 (505-YQPYRVVVLSFELLHAP-521) and 29 (512-VLSFELLHAPATVCGPK-528) successfully activated CD8 T cells.ConclusionsThese findings underscore that antigen multimerization and the strategic combination of adjuvants can significantly improve vaccine immunogenicity. |
| format | Article |
| id | doaj-art-8905367cb3784c8cb0c1180486f4d13c |
| institution | Kabale University |
| issn | 1664-3224 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Immunology |
| spelling | doaj-art-8905367cb3784c8cb0c1180486f4d13c2025-08-20T03:50:53ZengFrontiers Media S.A.Frontiers in Immunology1664-32242025-07-011610.3389/fimmu.2025.16104221610422Adjuvant combination and antigen multimerization shape neutralizing antibody and T cell responses to a SARS-CoV-2 RBD subunit vaccineJoão Pedro da Silva Nunes0Mariângela de Oliveira Silva1Juliana de Souza Apostolico2Isabela Pazotti Daher3Rodolfo Ferreira Marques4Marcio Massao Yamamoto5Alexia Adrianne Venceslau Brito Carvalho6Maria Fernanda de Castro-Amarante7Edison Luiz Durigon8Carsten Wrenger9Luiz Mario Ramos Janini10Edmarcia Elisa de Souza11Robert Andreata-Santos12Juliana Terzi Maricato13Edecio Cunha-Neto14Edecio Cunha-Neto15Edecio Cunha-Neto16Jorge Kalil17Jorge Kalil18Silvia Beatriz Boscardin19Silvia Beatriz Boscardin20Daniela Santoro Rosa21Daniela Santoro Rosa22Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo-Escola Paulista de Medicina (UNIFESP/EPM), São Paulo, BrazilDepartamento de Parasitologia, Universidade de São Paulo (USP), São Paulo, BrazilDepartamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo-Escola Paulista de Medicina (UNIFESP/EPM), São Paulo, BrazilLaboratório de Imunologia, Instituto do Coração (InCor), Hospital das Clínicas- Faculdade de Medicina- Universidade de São Paulo (HCFMUSP), São Paulo, BrazilDepartamento de Parasitologia, Universidade de São Paulo (USP), São Paulo, BrazilDepartamento de Parasitologia, Universidade de São Paulo (USP), São Paulo, BrazilDepartamento de Parasitologia, Universidade de São Paulo (USP), São Paulo, BrazilDepartamento de Parasitologia, Universidade de São Paulo (USP), São Paulo, BrazilDepartamento de Microbiologia, Universidade de São Paulo (USP), São Paulo, BrazilDepartamento de Parasitologia, Universidade de São Paulo (USP), São Paulo, BrazilDepartamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo-Escola Paulista de Medicina (UNIFESP/EPM), São Paulo, BrazilDepartamento de Parasitologia, Universidade de São Paulo (USP), São Paulo, BrazilDepartamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo-Escola Paulista de Medicina (UNIFESP/EPM), São Paulo, BrazilDepartamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo-Escola Paulista de Medicina (UNIFESP/EPM), São Paulo, BrazilLaboratório de Imunologia, Instituto do Coração (InCor), Hospital das Clínicas- Faculdade de Medicina- Universidade de São Paulo (HCFMUSP), São Paulo, BrazilLaboratório de Investigação Médica (LIM-19), Faculdade de Medicina- Universidade de São Paulo (FMUSP), São Paulo, BrazilInstituto de Investigação em Imunologia (iii), Instituto Nacional de Ciência e Tecnologia (INCT), São Paulo, BrazilLaboratório de Imunologia, Instituto do Coração (InCor), Hospital das Clínicas- Faculdade de Medicina- Universidade de São Paulo (HCFMUSP), São Paulo, BrazilInstituto de Investigação em Imunologia (iii), Instituto Nacional de Ciência e Tecnologia (INCT), São Paulo, BrazilDepartamento de Parasitologia, Universidade de São Paulo (USP), São Paulo, BrazilInstituto de Investigação em Imunologia (iii), Instituto Nacional de Ciência e Tecnologia (INCT), São Paulo, BrazilDepartamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo-Escola Paulista de Medicina (UNIFESP/EPM), São Paulo, BrazilInstituto de Investigação em Imunologia (iii), Instituto Nacional de Ciência e Tecnologia (INCT), São Paulo, BrazilIntroductionThe rapid development and deployment of multiple safe and effective COVID-19 vaccines were critical cornerstones of pandemic control. However, vaccine inequity and the emergence of new variants of concern (VOCs) highlighted major gaps in the global strategy to control SARS-CoV-2 infection. Despite the use of distinct platforms, most approved vaccines utilize the Spike protein as the main antigen due to its pivotal role in virus entry, mediated by the receptor binding domain (RBD). In this context, RBD stands out as a promising antigen for a subunit vaccine candidate, as it is the main target of neutralizing antibodies, has a well-established scalable production pipeline, and has proven safety. Approaches to enhance RBD immunogenicity encompass the addition of adjuvants and antigen multimerization. MethodsIn this study, we compared the immunogenic properties of the Wuhan RBD monomer and homodimer with an RBD heterotrimer formulation composed of the Delta, Beta and Gamma variants. We also screened different adjuvants to optimize both humoral and cellular immunity. ResultsOur results showed that immunization with the RBD dimer and trimer, in the presence of the adjuvant AddaS03, elicited a higher humoral response and a broader neutralization profile. Additionally, RBD-trimer immunization more efficiently inhibited viral replication in the lungs of mice challenged with the ancestral Wuhan strain compared to the monomer. We further optimized our vaccine formulation by combining the adjuvants AddaS03 and Poly I:C, which demonstrated a synergistic effect, integrating the potent humoral response induced by AddaS03 with the cellular Th1 skewing capacity of Poly I:C. The AddaS03+ Poly I:C mixture induced antibodies with higher affinity and an increased frequency of RBD-specific IgG2c-producing bone marrow plasma cells, highlighting the potential of this adjuvant combination to generate long-lived memory plasma cells. Additionally, we identified sequences within the RBD that induced specific IFNγ T cell responses. Peptide 12 (393-TNVYADSFVIRGDEVRQ-409) emerged as the immunodominant CD4 T cell epitope, whereas peptides 28 (505-YQPYRVVVLSFELLHAP-521) and 29 (512-VLSFELLHAPATVCGPK-528) successfully activated CD8 T cells.ConclusionsThese findings underscore that antigen multimerization and the strategic combination of adjuvants can significantly improve vaccine immunogenicity.https://www.frontiersin.org/articles/10.3389/fimmu.2025.1610422/fullSARS-CoV-2RBDvaccinerecombinant proteinadjuvant |
| spellingShingle | João Pedro da Silva Nunes Mariângela de Oliveira Silva Juliana de Souza Apostolico Isabela Pazotti Daher Rodolfo Ferreira Marques Marcio Massao Yamamoto Alexia Adrianne Venceslau Brito Carvalho Maria Fernanda de Castro-Amarante Edison Luiz Durigon Carsten Wrenger Luiz Mario Ramos Janini Edmarcia Elisa de Souza Robert Andreata-Santos Juliana Terzi Maricato Edecio Cunha-Neto Edecio Cunha-Neto Edecio Cunha-Neto Jorge Kalil Jorge Kalil Silvia Beatriz Boscardin Silvia Beatriz Boscardin Daniela Santoro Rosa Daniela Santoro Rosa Adjuvant combination and antigen multimerization shape neutralizing antibody and T cell responses to a SARS-CoV-2 RBD subunit vaccine Frontiers in Immunology SARS-CoV-2 RBD vaccine recombinant protein adjuvant |
| title | Adjuvant combination and antigen multimerization shape neutralizing antibody and T cell responses to a SARS-CoV-2 RBD subunit vaccine |
| title_full | Adjuvant combination and antigen multimerization shape neutralizing antibody and T cell responses to a SARS-CoV-2 RBD subunit vaccine |
| title_fullStr | Adjuvant combination and antigen multimerization shape neutralizing antibody and T cell responses to a SARS-CoV-2 RBD subunit vaccine |
| title_full_unstemmed | Adjuvant combination and antigen multimerization shape neutralizing antibody and T cell responses to a SARS-CoV-2 RBD subunit vaccine |
| title_short | Adjuvant combination and antigen multimerization shape neutralizing antibody and T cell responses to a SARS-CoV-2 RBD subunit vaccine |
| title_sort | adjuvant combination and antigen multimerization shape neutralizing antibody and t cell responses to a sars cov 2 rbd subunit vaccine |
| topic | SARS-CoV-2 RBD vaccine recombinant protein adjuvant |
| url | https://www.frontiersin.org/articles/10.3389/fimmu.2025.1610422/full |
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