Antibodies against a Leishmania infantum peroxiredoxin as a possible marker for diagnosis of visceral leishmaniasis and for monitoring the efficacy of treatment.

Diagnosis of leishmaniasis is frequently based on serological methods, such as direct agglutination, immunofluorescence tests and ELISA assays with Leishmania total extracts, as antigen, however due to highly inconclusive results, more reliable tests are needed. In the present study, the prevalence of antibodies to a number of recombinant proteins (LmSIR2, LmS3a, LimTXNPx, LicTXNPx and LiTXN1) highly conserved among Leishmania species, were evaluated by ELISA in Leishmania infantum infected children from an endemic area of Portugal. We found that sera from children patients had antibodies against the different recombinant proteins, LicTXNPx presented the highest immuno-reactivity compared to the other and the most often recognized in the case of acute visceral leishmaniasis (VL). Moreover, in children treated with meglumine antimoniate or amphotericin B, antibodies against some of the recombinant proteins declined, whereas conventional serology using crude extracts showed little or no difference between the pre- and post-treatment values. The highest reduction was observed in the case of antibodies against the LicTXNPx protein. These results suggest that the antibodies against LicTXNPx might be a useful constituent of a defined serological test for the diagnosis and the monitoring of the therapeutic response in VL. The monitoring and follow-up in a large-scale field trials of such marker in areas where leishmaniasis is endemic will lend support to this.