Diagnostic and Prognostic Value of K39 Recombinant Antigen in Indian Leishmaniasis

Abstract

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 potential in Indian kala-azar (VL) and post kala-azar dermal leishmaniasis (PKDL). Anti-rK39 antibodies were highly positive in 20 symptomatic cases, including 6 resistant to single or double chemotherapy, but became negligible or absent in 9 recently cured patients. Endpoint titration of samples from the 20 active cases showed that the anti-rK39 IgG titers fell within a wide range of 10(-2) to > 10(-6), and that their mean was > 1 order of magnitude higher than in VL reported previously. The anti-rK39 IgG titers were correlated with parasite burden found in the patients and remained undiminished in those refractory to chemotherapy. These results indicate that: (1) the K39 epitope is conserved in Indian strains of Leishmania donovani, (2) the extremely high levels of K39 antibodies in both VL and PKDL suggest the application of rK39 for sensitive and specific serodiagnosis, and (3) rK39 ELISA is also valuable for prognostic evaluation of both diseases.

Significance of persistence of antibodies against Leishmania infantum in sicilian patients affected by acute visceral leishmaniasis

“…One explanation might be that individuals with VL do not show complete elimination of the parasite. This agrees with the opportunistic occurrence of the diseases, as observed in patients with AIDS [19][20][21][22][23][24][25].…”

Value of a dipstick based on recombinant rK39 antigen for differential diagnosis of American visceral leishmaniasis from other sympatric endemic diseases in Venezuela

“…A 100 % specificity of this protein had been previously reported in Brazil using sera from patients with tropical diseases other than AVL (Badarô et al, 1996). A good specificity has been also reported in the Old World (Singh et al, 1995;Sundar et al, 1998;Jelinek et al, 1999). In Venezuela AVL, Chagas Disease, malaria, schistosomiasis and toxoplasmosis overlap in some areas.…”

ELISA with Recombinant rKRP42 Antigen Using Urine Samples: A Tool for Predicting Clinical Visceral Leishmaniasis Cases and Its Outbreak

“…A similar relationship between the high occurrence of clinical VL and high antibody titers was reported in the works by Singh and others. 20,27 The same works also noted that antirK39 IgG titer in serum correlated with the parasite load and that persistent increase of antibody titers related to clinical unresponsiveness to antileishmanial treatment. The prevalence by rKRP42 urine ELISA alone does not seem to be useful, because in the first test, the highest rate was recorded in center 2 (Tables 1 and 2); however, the clinical rate there turned out to be the lowest, with only one sporadic VL case.…”