Fig. 7: Vaccination during infection reduces CD8⁺ T cell response and cannot be rescued by IFNαR blockade.

A Experimental timeline for infectious challenge. Mice were injected IP with MAR1-5A3 antibody (αIFNαR) or PBS on Day −2. On Day −1, mice were inoculated with D220 virus. The following day mice were immunized with control eGFP mRNA-LNP or OVA mRNA-LNP. Seven days later mouse spleens were analyzed for SIINFEKL-H2-K^b specific CD8⁺ T cells. B Percent weight change of C57BL/6J wild-type mice (WT) either only given mRNA-LNP (black), mRNA-LNP after being infected with Dengue virus (blue), or given MAR1-5A3 24 h before infection with Dengue virus then immunized with mRNA-LNP a day later (red). C (Left) Representative flow plot of SIINFEKL-H2-K^b (OVA) specific CD8⁺ T cells. (Right) Percentage of OVA specific CD8⁺ T cells from WT mice given OVA mRNA-LNP only (black, n = 4), Dengue infected mice given OVA mRNA-LNP (blue, n = 8), or mice given MAR1-5A3 24 h prior to infection with Dengue virus then immunized with OVA mRNA-LNP a day later (red, n = 8). D (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. 7C. MAR1-5A3 was administered at 250 μg IP, mRNA-LNP was administered at 2.5 μg IV, and mice were infected with Dengue virus with 6.5 × 10⁶ FFU IM. Error bars in (B) indicate ± SD. All bars in (C, D) indicate mean. Data in (C) was compared using either an unpaired two-tailed students T test or a Mann–Whitney test. Data in (D) was compared using an unpaired two-tailed students T test.