Fig. 1

Δ42PD1 enhanced adaptive immune response against fusion expressed p24 antigen. A Schematic representation of DNA vaccine constructs. B Schematic representation of mice immunization schedule. C ELISA analysis of anti-p24 plasma antibody titers post-immunization of indicated vaccines (n = 15). The dotted line indicates the lower detection limit. D ELISpot analysis of p24-specific CD4⁺ and CD8⁺ T cell responses by stimulating splenocytes of immunized mice with indicated p24 peptides (n = 6). SFC, spot forming cells. E The gating strategy for tetramer⁺ CD8 T cells and representative plots. F The frequency of tetramer⁺ CD8 T cells in indicated vaccination groups (n = 15). G Tumor size in immunized mice was estimated by two-dimensional caliper measurement post-injection of AB1-Gag cells (n = 8). H Tumor-bearing mice were sacrificed at day 21 post-challenge, and the tumors were shown. I, J Mice were vaccinated with the mixture of the P24 vaccine with vector (P24) or pVAX-Δ42PD1 (P24 + Δ42PD1), or with the vector alone (n = 5). Two weeks after the last immunization, anti-p24 plasma antibody level I and antigen-specific T cells response to stimuli of p24 peptide pool J were determined. K, L TLR4 knockout mice were vaccinated with P24, Δ42PD1-P24 vaccines or pVAX1 vector (n = 6). Two weeks after the last immunization, anti-p24 plasma antibody level K and antigen-specific T cells response to stimuli of p24 peptide pool L were determined. C, D, F, G, I, L Data was represented as mean ± SEM of samples in the group. All statistical analyses were performed by student's t-test (Mann-Whitney test) using GraphPad Prism 8.0 software. *P < 0.05, **P < 0.01, ****P < 0.0001, n.s., not significant