FIG 8.
Reactivity of sera from B. microti-infected individuals against the recombinant BbRON2peptide. Human blood samples were screened for the presence of parasites by microscopy and PCR, and then the reactivity of the sera against the recombinant BbRON2peptide was determined for all available samples. Only samples H1 and H2 were identified to be positive for B. microti by Giemsa staining; however, the OD readings of serum samples H1 and H2 at the highest concentration tested in the ELISA were only 0.17 and 0.33, respectively. Parasites were never observed in the remaining five human samples, but the samples were PCR positive. Both serum sample H6 and serum sample H4 showed a greater reactivity at the 1:50 dilution, with ODs of 0.59 and 0.45, respectively, suggesting that the patients from whom these samples were obtained had recently been infected with Babesia parasites or had been harboring subpatent parasite loads for a long period of time, allowing anti-RON2 antibodies to accrue to levels higher than those in parasite-positive individuals. Error bars show the standard error of the mean ODs.