Enzyme-Linked Immunosorbent Assay Based on Soluble Promastigote Antigen Detects Immunoglobulin M (IgM) and IgG Antibodies in Sera from Cases of Visceral and Cutaneous Leishmaniasis

Abstract

Leishmaniasis causes significant morbidity and mortality in areas where it is endemic. In areas where it is nonendemic, global travel and increased incidence of the disease in human immunodeficiency virus and intravenous-drug user populations are also causes for concern. The unavailability of rapid and reliable tests for diagnosis of the various leishmaniases makes patient management difficult. We have developed an enzymelinked immunosorbent assay (ELISA) that can detect immunoglobulin M (IgM) and IgG antibodies in patients with visceral and cutaneous leishmaniasis. These practical assays are based on soluble antigens from promastigotes cultivated in a protein-free medium. In preliminary studies, 129 visceral (Brazil, Italy, North Africa, and Nepal) and 143 cutaneous (Brazil) leishmaniasis patients with controls were tested. Overall, the tests showed a sensitivity of 95.1%. In addition, the ELISA correctly identified 42 sera from Brazilian dogs with canine leishmaniasis and 10 healthy controls. Serological tests for the various clinical manifestations of leishmaniasis could be useful epidemiological and patient management tools in populations of areas of endemicity and nonendemicity.

The Efficacy of L. (L.) chagasi Excreted-Secreted Antigens (ESAs) for Visceral Leishmaniasis Diagnosis Is Due To Low Levels of Cross-Reactivity

“…Indeed, our findings of a 37.5% positivity of ESA with CL and 13.3% with the MCL cases (Table 1) do not agree with those of other authors who have reported 80-92.3% and 71% positive rates when CL samples were assayed with ESA isolated from L. (L.) mexicana and L. (V.) braziliensis, respectively. 13,15 In contrast, similar positivity rates (62.5% for CL and 73.3% for MCL) were observed in our study when Leishmania spp. PRO was used (Table 1).…”

“…have been a target of interest for decades and have been identified as potential candidates for vaccines, 32 they have not been extensively explored for the diagnosis of leishmaniasis. 5,6,12,13,15 In this report, we present new data suggesting that ESAs isolated from three different species of Leishmania (from the most prevalent species in the Americas) L.…”

“…8,11 Leishmania spp. conditioned medium has been used as a potential source of antigens for immunodiagnosis in the detection of cases of human VL, 5,6,12,13 canine leishmaniasis, 12,14 and cutaneous leishmaniasis (CL). 13,15 Although serological tests, such as the direct agglutination test, immunofluorescence test, indirect hemagglutination assay, enzyme-linked immunosorbent assay (ELISA), and Western blotting have been found to display high levels of sensitivity, the specificity indices were not significant.…”

“…conditioned medium has been used as a potential source of antigens for immunodiagnosis in the detection of cases of human VL, 5,6,12,13 canine leishmaniasis, 12,14 and cutaneous leishmaniasis (CL). 13,15 Although serological tests, such as the direct agglutination test, immunofluorescence test, indirect hemagglutination assay, enzyme-linked immunosorbent assay (ELISA), and Western blotting have been found to display high levels of sensitivity, the specificity indices were not significant. 1,2 The reason for this result may be because the antigens used in immunodiagnostic tests are usually derived from crude promastigotes of different Leishmania species, which express a variety of complex molecules that are common to other microorganisms, such as Trypanosoma, Plasmodium, and Mycobacterium, [16][17][18][19][20] or proteins that can react non-specifically.…”

Serological screening for Leishmania infantum in asymptomatic blood donors living in an endemic area (Sicily, Italy)

“…DiVerent reports documented parasitemia in asymptomatic L. infantum-seropositive blood donors [12,13]. Several hypotheses may be proposed to explain our diVerent results: (i) the screened sample is not wide enough although it is similar to that studied by other authors in the Mediterranean area [12,13]; (ii) the antibody titer may be so low that the tests used are not able to detect it; the global sensitivity of the tests used is reported to range from 95% to 100% in an immunocompetent host [19,20], but asymptomatic subjects show a low humoral immunoresponse so that their antibody levels are under the cut-oV; (iii) ELISA and IFAT are rapid and not very expensive techniques, but they are less sensitive than western blotting, which may give positive results even if classical serological tests are negative [13].…”