Protection against Experimental Melioidosis following Immunisation with a Lipopolysaccharide-Protein Conjugate

Figure 2

Survival of vaccinated mice following challenge with B. pseudomallei K96423. Mice were vaccinated three times at two-week intervals with 10 μg of either the TetH_c-LPS conjugate (∙), LPS alone (□), a mix of unconjugated LPS and TetH_c (▾), TetH_c only (Δ), or PBS (x) and challenged five weeks after the final vaccination with approximately 40 MLD of B. pseudomallei K96243. The data from two studies is combined in this figure with survival curves analysed by a stratified logrank test. We found no evidence (𝑃>0.05) for cross experimental variation in any vaccine group other than the TetH_c group where animals survived less well in the second experiment (𝑃<0.05). All of the vaccine containing B. pseudomallei LPS offered significant protection compared to the unvaccinated control (𝑃<0.001, in all cases) and the TetH_c treated group (𝑃<0.001, in all cases). We observed no statistical difference between the groups vaccinated with conjugate, LPS, or the mix of TetH_c and LPS (𝑃>0.05, in all cases).