Fig. 4: Inducing IFN before mRNA-LNP vaccination reduces vaccine efficacy.

A Experimental timeline for (B) and (C). Mice were injected IP with MAR1-5A3 antibody or PBS on Day −2. On Day −1, mice were immunized eGFP mRNA-LNP or PBS. The following day mice were immunized with OVA mRNA-LNP. Seven days later mouse spleens were analyzed for SIINFEKL-H2-K^b specific CD8⁺ T cells. B (Left) Representative flow plots of SIINFEKL-H2-K^b (OVA) specific CD8⁺ T cells. (Right) Percentage of OVA specific CD8⁺ T cells from C57BL/6J wild-type mice (WT) given only OVA mRNA-LNP (black, n = 5), eGFP mRNA-LNP then 24 h later given OVA mRNA-LNP (E.O) (blue, n = 6), or MAR1-5A3 then 24 h later given eGFP mRNA-LNP followed by OVA mRNA-LNP 24 h after eGFP (red, n = 6) (M.E.O). 2.5 μg of mRNA-LNP was administered IV and 250 μg of MAR1-5A3 was administered IP. C (Left) Representative flow plot showing PD-1 expression of OVA specific TCRβ⁺CD8α⁺ T cells. (Right) PD-1 expression of TCRβ⁺CD8α⁺ T cells from mice in Fig. 4B. D Experimental timeline for (E) and (F). Mice were injected with eGFP mRNA-LNP or PBS on Day −1. The following day mice were immunized with OVA mRNA-LNP. Seven days later mouse spleens were analyzed for SIINFEKL-H2-K^b specific CD8⁺ T cells. E (Left) Representative flow plots of OVA specific CD8⁺ T cells. (Right) Percentage of OVA specific CD8⁺ T cells from IFNαR^WT mice given just OVA mRNA-LNP (black, n = 6), IFNαR^WT mice given eGFP mRNA-LNP then 24 h later given OVA mRNA-LNP (blue, n = 6), and IFNαR^cKO mice given eGFP mRNA-LNP then 24 h later given OVA mRNA-LNP (red, n = 6). F (Left) Representative flow plot showing PD-1 expression of OVA specific TCRβ⁺CD8α⁺ T cells. (Right) PD-1 expression of TCRβ⁺CD8α⁺ T cells from mice in Fig. 4E. All bars in (B), (C), (E), and (F) indicate mean. Data from (B) and (E) were compared using an unpaired two-tailed students T test. Data in (C) and (F) were compared with either an unpaired two-tailed students T test or a Mann–Whitney test.