Fig. 4

Rp@Al-based protective immunity prevents MRSA-induced recurrent infections by eliciting pathogen-specific immunological memory. a Schematic illustration of the evaluation of protective immunity and prevention of MRSA-induced recurrent infections. Mice were injected subcutaneously (s.c.) with MRSA (10⁹ CFU, first exposure) followed by different treatments on Day 2. After 4 weeks, serum, lymph nodes, and spleens of mice in different treatment groups were collected for protective immunity analysis. Prevention of recurrent infections was evaluated by s.c. re-infection with MRSA(10⁹ CFU, second exposure). b, c Quantitative analysis of serum IL-4 (b) and IFNγ (c) levels on Day 30 (mean ± SEM, n = 5). d, e Percentage of CD45⁺ B220⁺ memory B cells in lymph nodes (d) and spleens (e) from mice in different treatment groups on Day 30 (mean ± SEM, n = 5). f, g Culture plate images (f) and quantitative analysis (g) showing the antibacterial ability of different treatments after s.c. re-infection with MRSA (mean ± SEM, n = 5). h Schematic diagram showing the mechanism of Rp@Al-based prevention of recurrent infections with MRSA. ns, no significance, *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001