DIAGNOSTIC AND PROGNOSTIC VALUE OF K-39 RECOMBINANT ANTIGEN IN INDIANLEISHMANIASIS

The recombinant product (rK39) of the 39 amino acid repeats encoded by a kinesin-like gene of visceral Leishmania spp. was further evaluated by enzyme-linked immunosorbent assay (ELISA) for its diagnostic poten tial in Indian kala-azar (VL) and post kala-azar dermal leishmaniasis (PKDL). Anti-rK39 antibodies were highly positive in 20 symptomatic ca ses, including 6 resistant to single or double chemotherapy, but becam e negligible or absent in 9 recently cured patients. Endpoint titratio n of samples from the 20 active cases showed that the anti-rK39 IgG ti ters fell within a wide range of 10(-2) to >10(-6), and that their mea n was > 1 order of magnitude higher than in VL reported previously. Th e anti-rK39 IgG titers were correlated with parasite burden found in t he patients and remained undiminished in those refractory to chemother apy. These results indicate that: (1) the K39 epitope is conserved in Indian strains of Leishmania donovani, (2) the extremely high levels o f K39 antibodies in both VL and PKDL suggest the application of rK39 f or sensitive and specific serodiagnosis, and (3) rK39 ELISA is also va luable for prognostic evaluation of both diseases.