Figure 5.

(a) Time schedule of the vaccine efficacy experiment and (b) experimental proof of Mycobacterium tuberculosis infection. In Ziehl–Neelsen-stained histologic sections prepared from the spleen, numerous acid-fast rod-shaped organisms were observed ((b), arrows point at Mtb cells). Magnification: 100× on the left panel, 600× on the right panel of (b). The vaccine efficacy of the pal-A(P)I conjugate was proved by enumerating a lower number of Mycobacterium tuberculosis (Mtb) bacteria from (c) spleen and (d) lung homogenates. Statistical significance was analyzed by Mann–Whitney U test (confidence intervals: 95%).