Detection and characterization by immunoblot analysis of potentially diagnostic Leishmania infantum polypeptides in human visceral leishmaniasis

Humoral immune responses were studied in 53 sera from 18 patients with visceral leishmaniasis by immunoblot analysis. Sera from visceral leishmaniasis patients recognized antigens with molecular weights ranging from < 14kDa to more than 100 kDa. Bands ranging between 49 and < 14 kDa were the most specific. The 40, 33 and 17kDa antigens were recognized by 90%, 79% and 79% of the patients sera, respectively. Sera from one patient with Chagas' disease identified 8 of 11 antigens of the specific region. Treatment with periodate eliminated the cross-reaction in three of these antigens (40, 29, 26 kDa). The study of serial sera collected from the different patients showed a decrease in intensity or dissappearance in some of the diagnostic bands, particularly the 17 kDa band. The band of 17 kDa seems to be useful to study the clinical evolution, for post-treatment control and also for epidemiologic purposes. (It has been identified in 7% of control sera from endemic areas.) Immunoblot could be a valuable tool in the diagnosis of visceral leishmaniasis, being more sensitive and specific than other serologic tests.