Figure 7.

Immunization schedule and protective efficacy of immunization with LV20 in adjuvant DP against M. tuberculosis H37Ra infection. (A) The immunization schedule to assess protective efficacy. C57BL/6 mice were immunized with BCG and PBS one-time inoculation on day 0. HBHA/DP, LV20 and LV20/DP were immunized subcutaneously three times on days 0, 28 and 84. H37Ra (5 × 10⁶ CFU in 50 μL per mouse) intranasal challenge occurred days 84 after the last immunization and 21 days after challenge; lung tissues were collected for CFU counting. PBS and BCG groups were used as control. There were at least 5 mice per group. (B) The evaluation of protective efficacy against H37Ra. Eighty-four days after the last vaccination, mice were challenged with 5 × 10⁶ CFU of M. tuberculosis H37Ra via intranasal route. Twenty-one days later, the animals were euthanized and CFU counts in lungs were determined. Results are presented as mean ± SD of log10 CFU/lung from groups of 5–6 mice. Unpaired two-tailed Student’s t-tests were used to compare the two groups and one-way analysis of variance including a Tukey post hoc test was used to compare three or more groups. ** p < 0.01.