FIG. 4.

LTB-specific IgA in fecal samples of mice inoculated i.g. Two groups of eight BALB/c mice each were immunized with either the vaccine strain GP1246 (solid bars) or the control strain GP246 (open bars) as described for Fig. 2. Inoculations were performed at weeks 0 and 4. Feces were collected at weeks 0, 2, 4, 5, 6, 7, and 8. To calculate the concentrations of total and LTB-specific IgA, a standard curve of mouse myeloma IgA was used. The concentration of LTB-specific IgA was determined in pools of fecal samples containing 10 μg of total IgA from each sample per ml. The amount of LTB-specific IgA was normalized to the concentration of total IgA and expressed in micrograms of specific IgA per milligram of total IgA. Antigen-specific IgA in pooled preimmune fecal samples is also reported (gray bar).