Fig. 4

Immunological evaluation of KPO1-VLP in mice. a Experimental schedule for the immune assessment. b SDS-PAGE assays of KPO2-SC glycoprotein, KPO2-VLP conjugate nanovaccines, KPO1-SC glycoprotein, KPO1-VLP conjugate nanovaccines, and ST-AP205 nanoparticles. c ELISA-based measurement of IgG titers against K. pneumoniae strain 041 LPS after three subcutaneous immunizations for OPS-KPO1, KPO1-SC, KPO1-VLP, ST-AP205, and sterile 1 × PBS groups of BALB/c mice IgG titers. Fourteen days after the final immunization, 10 mice per group were injected intraperitoneally with K. pneumoniae strain 041 (2 × 10⁴ CFU per mouse), and survival was monitored for 7 d. Differences between groups were evaluated using an unpaired one-way analysis of variance (ANOVA) (****p < 0.0001). d ELISA-based measurement of IgG titers against K. pneumoniae strain 041 LPS after three subcutaneous immunizations of BALB/c mice using KPO1-VLP at different glycan levels with a sterile 1 × PBS group control. Fourteen days after the final immunization, 10 mice in each group were injected intraperitoneally with K. pneumoniae strain 041 (2 × 10⁴ CFU per mouse), and survival was monitored for 7 d. Differences between groups were evaluated using unpaired one-way analysis of variance (ANOVA) (ns, differences not statistically significant). e BALB/c mice were immunized once subcutaneously using KPO1-VLP (immunization dose of 12.5 μg glycan per mouse) with a sterile 1 × PBS group control; changes in body temperature and body weight were monitored 14 days after immunization. f Serum biochemical parameters including alanine aminotransferase (ALT), alanine aminotransferase (ALP), aminotransferase (AST), blood urea nitrogen (BUN), and lactate dehydrogenase (LDH) were monitored 28 days after immunization. g The heart, liver, spleen, lungs, and kidneys were isolated for pathological sectioning 28 days after immunization. Scale bar: 50 nm