A Modified Recombinant DNA-Based SARS-CoV-2 Vaccine Expressing Stabilized Uncleavable Spike Protein Elicits Humoral and Cellular Immunity against Various SARS-CoV-2 Variants of Concern

Figure 3

Cytokines response in CD4⁺ and CD8⁺ T cells from spleens and draining inguinal lymph nodes. Cells isolated from the spleens and draining inguinal lymph nodes were obtained from VIU-1007-immunized and control mice 5 weeks after receiving two or three doses. Cells were ex vivo restimulated with pooled peptides covering the complete S protein for 6 hr. After the first hour of culture, Brefeldin A was added. The cells were then incubated with live/dead viability and antibodies against CD4, CD8, CD62L, and CD44 (surface staining) and with antibodies for IFN-γ and IL-2 (intracellular staining). (a) Representative FACS plots of the gating strategies on live CD8⁺CD44^hiCD62L⁺ central memory T cells, effector CD8⁺CD44^hiCD62L⁻ memory T cells, and memory CD4⁺CD44^hiCD62L⁻ T cells. Representative FACS plots (left) and histograms (right) displaying the percentages of IFN-γ and IL-2 expression by (b) central memory CD8⁺ T cells, (c) effector memory CD8⁺ T cells, and (d) memory CD4⁺ T cells. All the represented data were calculated by subtracting the values of the expressed cytokine by nonstimulated cells from the re-stimulated cells. Results are represented as mean ± SD from one experiment (n = 7). Statistical significance is reported as , , , and .

(a)

(b)

(c)

(d)