Evaluation of a new set of recombinant antigens for the serological diagnosis of human and canine visceral leishmaniasis

PLoS One. 2017 Sep 28;12(9):e0184867. doi: 10.1371/journal.pone.0184867. eCollection 2017.

Abstract

Current strategies for the control of zoonotic visceral leishmaniasis (VL) rely on its efficient diagnosis in both human and canine hosts. The most promising and cost effective approach is based on serologic assays with recombinant proteins. However, no single antigen has been found so far which can be effectively used to detect the disease in both dogs and humans. In previous works, we identified Leishmania infantum antigens with potential for the serodiagnosis of VL. Here, we aimed to expand the panel of the available antigens for VL diagnosis through another screening of a genomic expression library. Seven different protein-coding gene fragments were identified, five of which encoding proteins which have not been previously studied in Leishmania and rich in repetitive motifs. Poly-histidine tagged polypeptides were generated from six genes and evaluated for their potential for diagnosis of VL by ELISA (Enzyme Linked ImmunoSorbent Assay) with sera from infected humans and dogs. None of those was valid for the detection of human VL (26-52% sensitivity) although their performance was increased in the canine sera (48-91% sensitivity), with one polypeptide useful for the diagnosis of canine leishmaniasis. Next, we assayed a mixture of three antigens, found to be best for human or canine VL, among 13 identified through different screenings. This "Mix" resulted in similar levels of sensitivity for both human (84%) and canine (88%) sera. With improvements, this validates the use of multiple proteins, including antigens identified here, as components of a single system for the diagnosis of both forms of leishmaniasis.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, Protozoan / chemistry
  • Antigens, Protozoan / immunology*
  • Dogs
  • Electrophoresis, Polyacrylamide Gel
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Leishmania infantum / immunology
  • Leishmaniasis, Visceral / blood
  • Leishmaniasis, Visceral / diagnosis*
  • Leishmaniasis, Visceral / veterinary*
  • Peptides / metabolism
  • Recombinant Proteins / immunology*
  • Sequence Analysis, Protein
  • Serologic Tests / methods*

Substances

  • Antigens, Protozoan
  • Peptides
  • Recombinant Proteins

Grants and funding

The work in Dr. de Melo Neto’s laboratory was more recently funded with grants provided by the Brazilian funding agency CNPq and the Brazilian Ministry of Health (Grant MCTI/CNPq/MS-SCTIE No.: 404259/2012). The work in Dr. C. H. N. Costa’s lab was funded by CNPq (Grant 554797). Fellowships and studentships for the graduate students (FBM, ALCN, MBN, WJTS and ASLN) were provided by CNPq, FACEPE or CAPES. The work carried out at Fiocruz-BA was funded by the Brazilian Ministry of Science and Technology (Program RENORBIO). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.