Figure 4

Effect of pre-existing DT antibodies on immunogenicity of CRM conjugated vaccines. (A) Cohorts of BALB/c mice were immunised intramuscularly with three doses of DT/Alum at 30 μg each on day 0, 21 and 28. Serum samples were collected one-week post-last boost and then following a rest period of four weeks to measure DT-specific serum IgG. This was followed by three intramuscular immunisations (D0, D21 and D28) with MJ8CombiVax. In parallel, a cohort of naive BALB/c mice (without DT pre-immunisations) was also vaccinated with MJ8CombiVax. Both the DT primed and naive mice were tested for peptides and carrier specific IgG post immunisation with MJ8CombiVax. The mice were bled post each dose (d20, d27 and d35) and antigen specific IgG titers measured. The IgG titers for both the cohorts post each immunisation for DT (A), CRM (B), J8 (C) and K4S2 (D) are shown. Statistical analysis was performed using student t-test to determine significance between the two groups at each time points. ns, p > 0.05; *p < 0.05; **p < 0.01.