AUTHOR=del Fresno Carlos , García-Arriaza Juan , Martínez-Cano Sarai , Heras-Murillo Ignacio , Jarit-Cabanillas Aitor , Amores-Iniesta Joaquín , Brandi Paola , Dunphy Gillian , Suay-Corredera Carmen , Pricolo Maria Rosaria , Vicente Natalia , López-Perrote Andrés , Cabezudo Sofía , González-Corpas Ana , Llorca Oscar , Alegre-Cebollada Jorge , Garaigorta Urtzi , Gastaminza Pablo , Esteban Mariano , Sancho David TITLE=The Bacterial Mucosal Immunotherapy MV130 Protects Against SARS-CoV-2 Infection and Improves COVID-19 Vaccines Immunogenicity JOURNAL=Frontiers in Immunology VOLUME=12 YEAR=2021 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2021.748103 DOI=10.3389/fimmu.2021.748103 ISSN=1664-3224 ABSTRACT=

COVID-19-specific vaccines are efficient prophylactic weapons against SARS-CoV-2 virus. However, boosting innate responses may represent an innovative way to immediately fight future emerging viral infections or boost vaccines. MV130 is a mucosal immunotherapy, based on a mixture of whole heat-inactivated bacteria, that has shown clinical efficacy against recurrent viral respiratory infections. Herein, we show that the prophylactic intranasal administration of this immunotherapy confers heterologous protection against SARS-CoV-2 infection in susceptible K18-hACE2 mice. Furthermore, in C57BL/6 mice, prophylactic administration of MV130 improves the immunogenicity of two different COVID-19 vaccine formulations targeting the SARS-CoV-2 spike (S) protein, inoculated either intramuscularly or intranasally. Independently of the vaccine candidate and vaccination route used, intranasal prophylaxis with MV130 boosted S-specific responses, including CD8+-T cell activation and the production of S-specific mucosal IgA antibodies. Therefore, the bacterial mucosal immunotherapy MV130 protects against SARS-CoV-2 infection and improves COVID-19 vaccines immunogenicity.