biostudies-literatureGarcia-Arriaza JFerrovialFundación MapfreMEC | Instituto de Salud Carlos IIIMEC | Consejo Superior de Investigaciones CientíficasFondo Supera COVID-19Fundación Banco SantanderJVI.02260-20https://www.ebi.ac.uk/biostudies/studies/S-EPMC8092708biostudies-literatureUnknown95(7)Vaccines against SARS-CoV-2, the causative agent of the COVID-19 pandemic, are urgently needed. We developed two COVID-19 vaccines based on modified vaccinia virus Ankara (MVA) vectors expressing the entire SARS-CoV-2 spike (S) protein (MVA-CoV2-S); their immunogenicity was evaluated in mice using DNA/MVA or MVA/MVA prime/boost immunizations. Both vaccines induced robust, broad and polyfunctional S-specific CD4+ (mainly Th1) and CD8+ T-cell responses, with a T effector memory phenotype. DNA/MVA immunizations elicited higher T-cell responses. All vaccine regimens triggered high titers of IgG antibodies specific for the S, as well as for the receptor-binding domain; the predominance of the IgG2c isotype was indicative of Th1 immunity. Notably, serum samples from vaccinated mice neutralized SJournal of virologyCOVID-19 vaccine candidates based on modified vaccinia virus Ankara expressing the SARS-CoV-2 spike induce robust T- and B-cell immune responses and full efficacy in mice.PMC8092708COV20/001512020E84Perez PSorzano COSEsteban MCasasnovas JMLazaro-Frias ASancho DGastaminza PZamora CGarcia-Arriaza JDel Fresno CGaraigorta UfalseCOVID-19 vaccine candidates based on modified vaccinia virus Ankara expressing the SARS-CoV-2 spike induce robust T- and B-cell immune responses and full efficacy in mice.Vaccines against SARS-CoV-2, the causative agent of the COVID-19 pandemic, are urgently needed. We developed two COVID-19 vaccines based on modified vaccinia virus Ankara (MVA) vectors expressing the entire SARS-CoV-2 spike (S) protein (MVA-CoV2-S); their immunogenicity was evaluated in mice using DNA/MVA or MVA/MVA prime/boost immunizations. Both vaccines induced robust, broad and polyfunctional S-specific CD4+ (mainly Th1) and CD8+ T-cell responses, with a T effector memory phenotype. DNA/MVA immunizations elicited higher T-cell responses. All vaccine regimens triggered high titers of IgG antibodies specific for the S, as well as for the receptor-binding domain; the predominance of the IgG2c isotype was indicative of Th1 immunity. Notably, serum samples from vaccinated mice neutralized S2021-01-01T00:00:00Z2021 Mar2025-06-01T01:37:01.305Z2022-02-10T09:53:52.54ZS-EPMC80927083341415910.1128/JVI.02260-20