Figure 3.

PIM₆- and BCG-vaccination of guinea pigs is associated with significant reduction in necrosis and bacterial load. Four weeks after s.c. challenge with virulent Mtb, the same PIM₆-vaccinated [PIM] and control guinea pigs [CAF, BCG], six animals per group, were euthanized and necropsied. A gross pathology score shows the overall severity of granulomas as individual sum score (A) or focused at the organ level for the spleen (B), (n = 6) per group. (C–J) Tissue sections of the injection-site-granuloma, the draining lymph node and the spleen were stained with hematoxylin–eosin or immunophenotyped using an Mtb-specific antibody. In particular with BCG-vaccinated animals lesions were so small that we could not perform all analyses in parallel. The number of available histological specimen is depicted. The relative area of necrosis within granulomas and the number of Mtb-positive spots per mm² were determined for the injection-site-granuloma (C–E), the draining right axillary lymph node (F–H) and for the spleen (I, J). Representative sections are shown from CAF01-vaccinated animals. Black bars represent the group mean, error bars represent the standard error of the mean. Spleen homogenates from the three treated groups and from a group of six non-immunized guinea pigs were cultured and the number of colony-forming units are depicted. Circles indicate individual animals, bars represent the group mean. Asterisks indicate the level of significance as calculated by unpaired-t- or Mann–Whitney-test.