Fig. 3: PSs enhance protein delivery in vitro and stimulate antibodies in vivo from a single-dose subunit vaccine along with enhanced retention in injection site-draining lymph nodes.

a, Uptake of fluorescent OVA (FITC-OVA) by BMDCs measured by flow cytometry with corresponding fluorescence histograms on the right. Quantification of gMFI of the single, live population demonstrates significant uptake when the same amount of OVA is encapsulated in PSs compared with free FITC-OVA. b, Antigen presentation probed using BMDC co-culture with OTI labelled with CFSE, benchmarking against free OVA control. The histograms on the left show the distribution of CFSE fluorescence signal, and populations left of the dotted line are new generations of OTI cells (‘CFSE-diluted’) quantified by the bar graph on the right. c, Antibody levels measured by ELISA for C57BL/6 mice (n = 5) injected in all four hocks with a single prime vaccination. All non-saline treatments were with 10 µg OVA adjuvanted with 20 µg CpG ODN 1826. Blood was sampled periodically during a 90 day period and benchmarked to unencapsulated, adjuvanted OVA. d, Antibody levels measured 1 year post prime vaccination (vax). e, IVIS for relative fluorescence in hock-draining lymph nodes of OVA₆₄₇ injected either free or with PSs in all 4 hocks, where animals were killed 4 h after administration. Lymph nodes (n = 2 from each mouse) were collected from both sides and the following locations (top to bottom): axillary, brachial, inguinal and popliteal. f, Total radiant efficiency from brachial lymph nodes quantified. Data in a and b are technical replicates (n = 3) plotted as mean ± s.d. and compared using ordinary one-way ANOVA with Tukey’s post-test for multiple comparisons. Data in c and d are biological replicates (n = 5) plotted as mean ± s.e.m. for c and box plots with max/min, median and quartiles for d. P values for day 84 (c) and 1 year antibody levels from one-way ANOVA with Tukey’s post-test for multiple comparisons.