SDS-PAGE analysis (15%) of 3 μl of recombinant B13. Purity is > 98% as determined by gel electrophoresis. Bands which slightly appear at approx. 20 and 16 kDa correspond to this same protein as it is showed in a western blot performed with a his-tag monoclonal antibody

The titer has been suggested in reference to an "in-house" ELISA kit performed over the first lot obtained. ELISA assays were performed with a serum sample panel of 25 positive- specimen sera and 5 negative specimen sera, validated by chimioluminiscence (Architect, Abbot) and obtained from the Andalusian Public health System Biobank.
Each end user should carry out his own titration for his particular application.

In this plot, the optical density at 450/620 nm for positive (blue) and negative (gray) IgG sera for Chagas disease are compared for each concentration of the recombinant antigen. An appropriate statistical test of significance for the comparison of means between both groups, the Welch's test, is employed. Eligible concentrations for the use of the antigen should present statistically significant differences between positive and negative sera. This happens when the intervals at the top do not overlap and, equivalently, when the p-value at the bottom is below 0.05. In the present figure, all p-values are below 0.05 and thus the intervals do not overlap. Therefore, any of the showed concentrations can be used to distinguish between positive and negative sera.