Leishmania major-Like Antigen for Specific and Sensitive Serodiagnosis of Human and Canine Visceral Leishmaniasis

Abstract

An antigen (LMS) prepared from Leishmania major-like promastigotes was used in an enzyme-linked immunosorbent assay (ELISA) for the diagnosis of human and dog visceral leishmaniasis. The results were compared with those from the indirect immunofluorescent antibody test (IFAT). A total of 1,822 canine sera were tested, including sera from dogs with visceral leishmaniasis, transmissible venereal tumors, ehrlichiosis, rickettsiosis, or Chagas' disease and sera from healthy dogs. The antigen was also tested with 227 samples of human sera, including sera from patients with visceral, cutaneous, or diffuse cutaneous leishmaniasis and from noninfected individuals, as well as sera from patients with Chagas' disease, toxoplasmosis, rickettsiosis, hepatitis B, schistosomiasis, ascaridiasis, malaria, rheumatoid factor, leprosy and rheumatoid factor, tuberculosis, or leprosy. All dogs and all human patients had a clinical and/or serological and/or parasitological diagnosis. For detecting antibodies in sera from dogs with leishmaniasis, the antigen showed a sensitivity of 98%, specificity of 95%, and concordance of 93% and when used for detecting antibodies in human sera presented a sensitivity of 92%, specificity of 100%, and concordance of 92%. Comparison between ELISA and IFAT demonstrated that ELISA using the LMS antigen yielded more reliable results than IFAT. The LMS antigen displayed no cross-reactivity with sera from patients or dogs that had any of the other diseases tested.Leishmaniasis comprises a spectrum of diseases widely distributed in tropical and subtropical countries, ranging in severity from self-healing skin lesions to severely mutilating mucocutaneous involvement or visceral infections (kala-azar) caused by the protozoan hemoflagellate Leishmania. The leishmanial diseases, except for cutaneous leishmaniasis, have a lengthy incubation period, an insidious onset, and a chronic course. Kala-azar, or visceral leishmaniasis (VL), is characterized by irregular fever, progressive enlargement of the spleen and liver, leukopenia with marked neutropenia, anemia, emaciation, and discoloration of the skin. Leishmanial infections are accompanied by a dramatic humoral response against some forms of leishmania. A marked increase in immunoglobulin G (IgG) in serum and, to a lesser extent, IgM is the common feature in the majority of kala-azar patient sera (17).The antigens used in immunodiagnosis consist of a repertoire of at least 30 somatic antigens and an unknown number of surface components, and the existence of both heterospecific antigens and specific parasite antigens has been established (23, 27). As a result, to date most immunodiagnostic methods have been hampered by the problem of cross-reactivities of species within a family as well as with phylogenetically distant microorganisms (4,22,23,31,35). The problem is further complicated in geographical areas where different forms of leishmaniasis and trypanosomal infections occur simultaneously (27).The serological test most commonly used for diagnosis of leishmani...

Specific Serodiagnosis of Canine Visceral Leishmaniasis Using Leishmania Species Ribosomal Protein Extracts

“…SLA-based ELISAs has usually provided a high degree of sensitivity for the diagnosis of VL (6,31,44). By using sera from dogs with symptomatic CVL in a region of Brazil where VL is endemic, the sensitivity and specificity values obtained with the LRP extracts were similar to those shown by the use of SLA when the sera from healthy dogs obtained in the same region were employed as a control.…”

“…Lower sensitivity values were related to the variability in the heterogeneous humoral response elicited against parasite proteins observed in each patient or infected dog. The use of a combination of nonrelated antigens (25,42) or the production of polyproteins containing several parasite antigens (7, 49) (6). Since the sera from T. cruzi-or T. gondii-infected dogs were not able to recognize LRP extracts, whereas some of these sera showed a high degree of reactivity against SLA, our data indicate that LRP can be employed as a more specific antigen than SLA for the differential diagnosis of CVL.…”

“…However, due to the high degree of variability in the humoral responses to different parasite antigens observed in infected dogs (24,42), the efficient diagnosis of CVL based on recombinant proteins may require a mixture of recombinant proteins or the use of chimerical proteins containing several nonrelated parasite antigens (7,42,49). The specific diagnosis of CVL can also be developed by using preparations purified from the parasite (6,9) or crude parasite fractions analyzed by Western blotting (1,20).…”

Ocurrence of co-infection by Leishmania (Leishmania) chagasi and Trypanosoma (Trypanozoon) evansi in a dog in the state of Mato Grosso do Sul, Brazil

“…The domestic dog (Canis familiaris) has been considered an important reservoir of the Leishmania (Leishmania) chagasi in periurban and urban environments (Barbosa-de-Deus et al 2002); however, the role of this animal in the ACL transmission cycle has not yet been clarified (Reithinger & Davies 1999).…”

Epitope Mapping of the HSP83.1 Protein of Leishmania braziliensis Discloses Novel Targets for Immunodiagnosis of Tegumentary and Visceral Clinical Forms of Leishmaniasis

“…As an attempt to identify new targets for diagnosing multiple forms of leishmaniasis, we screened the L. braziliensis proteome to predict linear B-cell epitopes that are conserved in Leishmania spp. and divergent in H. sapiens, C. familiaris, and T. cruzi, the etiologic agent of Chagas disease, which often presents cross-reactivity with leishmaniasis due to sharing multiple common epitopes within the trypanosomatid species (34,35). Heat shock proteins (HSPs) are highly conserved molecules in prokaryotes and eukaryotes that play important roles in protein folding, assembly of protein complexes, and the translocation of proteins across cellular compartments (14).…”