A recombinant cysteine proteinase from Leishmania (Leishmania) Chagasi suitable for serodiagnosis of American visceral leishmaniasis

A recombinant protein, rLdccys1, which was produced by expression of the gene encoding a 30 kDa cysteine proteinase from Leishmania (Leishmania) chagasi, was used for detection of antibodies in sera from patients with active visceral leishmaniasis (VL) in enzyme-linked immunosorbent assays. Analysis of the predicted amino acid sequence of rLdccysl showed that it contains all the characteristics of a cysteine proteinase. The ability of the protein to react with sera from humans with VL was also shown by Western blotting. The sensitivity for detection of specific antibodies to L. (L.) chagasi bodies using rLdccysl, L. (L.) chagasi promastigote lysates, and amastigote lysates was 80%, 98%, and 99%, respectively. No cross-reactivity between rLdccysl and Chagas disease was observed, and there was little positive reactivity with sera from patients with cutaneous leishmaniasis and tuberculosis, compared with promastigote and amastigote extracts. Our findings indicate that rLdccysl from L. (L.) chagasi constitutes a potential tool for the diagnosis of American VL.