Figure 4.

MV130 increases immunogenicity elicited by a mucosal COVID-19 vaccine based on S-protein plus adjuvant. Three weeks after receiving excipient or MV130 according to Figure 1A , C57BL/6 mice were i.n. vaccinated with a COVID-19 vaccine based on the entire SARS-CoV-2 Spike (S) protein adjuvanted with R-848. Samples were collected 10 days later. (A, B) Bronchoalveolar lavage (BAL) was obtained from excipient and MV130-treated mice. Quantitative analysis of different myeloid (A) or lymphoid (B) immune populations identified by FACS. AMs, alveolar macrophages; cDC1s, type 1 conventional dendritic cells; cDC2s, type 2 conventional dendritic cells. (C, D) Lungs (C) and spleen (D) were recovered, and the effector phenotype (CD44⁺) of CD4⁺ and CD8⁺ T cells were analyzed. (E–G) Excipient and MV130-treated mice were i.n. prime-vaccinated with S-R848 1 week after the last immunotherapy inoculation. Two weeks later, mice were administered with a second booster dose of the vaccine. (E) BAL cellular composition was analyzed by t-distributed Stochastic Neighbor Embedding (tSNE) analysis from FACS data. This analysis included non-vaccinated mice together with mice vaccinated with one (1×) or two (2×) doses of the S-R848 vaccine. Dotted lines identify specific populations. AM, alveolar macrophages; cDC, conventional Dendritic cells; BC, B cells; Neu, neutrophils; TC, T cell. (F) Levels of SARS-CoV-2 S protein-specific total IgG, IgG1, IgG2c, and the ratio of IgG2c/IgG1 were analyzed in serum of vaccinated mice. Data correspond to values from sera diluted at 1/250. (G) Levels of SARS-CoV-2 S protein-specific mucosal IgA were analyzed in the BAL of vaccinated mice. Data correspond to values from BAL diluted at 1/1. (A–D, F–G) Data shown as mean ± SEM. (A–D) N=3. (F, G) N=2. (A–D, F, G) *p < 0.05; **p < 0.01; ***p < 0.001, Student’s t test comparing excipient versus MV130. (A–D) ^#p < 0.05 Student’s t test comparing non-vaccinated versus vaccinated conditions. (F, G) OD, optical density.