FIG 3.
Single-dose intranasal immunization with PIV5-MERS-S induced robust MERS-CoV-specific CD8 T cell response in human DPP4 knockin (hDPP4 KI) mice. (A) Schematic diagram showing the experimental plan to examine CD8 T cell response after immunization and challenge. hDPP4 KI mice were intranasally immunized with 104 PFU PIV5-MERS-S or PIV5-GFP. At 4 weeks or 4 days following immunization, mice were challenged with MERSMA6.1.2, single-cell suspensions from the lungs of immunized mice were stimulated with MERS-CoV spike peptides (S343 and S1165), and specific CD8 T cells were determined by IFN-γ intracellular staining. (B to D) Representative FACS plots (B), percentage (C), and total number (D) of MERS-CoV-specific CD8 T cells in the lungs at 4 weeks after immunization. (E to G) Representative FACS plots (E), percentage (F), and total number (G) of MERS-CoV-specific CD8 T cells in the lungs at 4 days after MERSMA6.1.2 challenge (n = 6 mice per group). Data are representative of two independent experiments. Data presented represent mean ± SE; * denotes P < 0.05 and ** denotes P < 0.01, Mann-Whitney test.