FIG. 6.

Anti-N. fowleri antibodies in serum and tracheopulmonary fluid of mice immunized and sacrificed 7 days after the last immunization or at different times after the lethal challenge. Four weekly doses of amoebal lysate (100 μg of protein) plus 50 μg of Cry1Ac were administered to mice by the i.n. route, and they were (i) sacrificed 7 days after the last immunization (bar 0), (ii) challenged in with 5 × 10⁴ virulent amoebae and sacrificed at different early days (bars 1 to 4), or (iii) sacrificed 60 days later (bar 60). Anti-N. fowleri IgA, IgG, and IgM antibody levels were determined by ELISA in serum samples diluted 1:1,000 (A) and undiluted tracheopulmonary fluid samples (B). Control mice were not immunized or challenged. Individual samples were run in duplicate. Each data point shows the man A₄₉₂ value mean ± SD (n = 5). Significant differences (P < 0.05) in the levels of each antibody isotype between groups are indicated as follows: +, versus group immunized and sacrificed 7 days after the last immunization.