Diagnostic application of sensitive and specific phage-exposed epitopes for visceral leishmaniasis and human immunodeficiency virus coinfection

Abstract

The diagnosis of visceral leishmaniasis (VL) has improved with the search of novel antigens; however, their performance is limited when samples from VL/human immunodeficiency virus (HIV)-coinfected patients are tested. In this context, studies conducted to identify more suitable antigens to detect both VL and VL/HIC coinfection cases should be performed. In the current study, phage display was performed using serum samples from healthy subjects and VL, HIV-infected and VL/HIV-coinfected patients; aiming to identify novel phage-exposed epitopes to be evaluated with this diagnostic purpose. Nine non-repetitive and valid sequences were identified, synthetized and tested as peptides in enzyme-linked immunosorbent assay experiments. Results showed that three (Pep2, Pep3 and Pep4) peptides showed excellent performance to diagnose VL and VL/HIV coinfection, with 100% sensitivity and specificity values. The other peptides showed sensitivity varying from 50.9 to 80.0%, as well as specificity ranging from 60.0 to 95.6%. Pep2, Pep3 and Pep4 also showed a potential prognostic effect, since specific serological reactivity was significantly decreased after patient treatment. Bioinformatics assays indicated that Leishmania trypanothione reductase protein was predicted to contain these three conformational epitopes. In conclusion, data suggest that Pep2, Pep3 and Pep4 could be tested for the diagnosis of VL and VL/HIV coinfection.

A systematic review of peptide-based serological tests for the diagnosis of leishmaniasis

“…[ 82 ], in which the cases were selected from a health service or hospital. To assess the performance of peptide-based tests, three different formats were reported: one study used an ICT format [ 7 ], two studies used phage-ELISA [ 15 , 62 ] and 19 studies used an ELISA technique [ 10 , 11 , 16 , 17 , 26 , 27 , 29 , 35 , 37 , 40 – 43 , 47 , 48 , 58 , 63 , 69 , 70 ]. In these studies using an ELISA method, a marked difference was observed in the amount of peptides used, which ranged from 0.25 μg to 20 μg per well.…”

“…et al ., 2020b [ 48 ] PeptJ Molecular technique (VL patients); serology (control group) ELISA 2 μg/well II VL Brazil L. infantum Ramos F.F. et al ., 2021 [ 58 ] Pep1 Molecular technique (VL and VL/HIV-coinfeted patients), serological test (Kalazar detect Rapid test kit) (control group) ELISA 2.5 μg/well II VL Brazil L. infantum Pep2 5 μg/well Pep3 5 μg/well Pep4 2.5 μg/well Pep5 1.25 μg/well Pep6 1.25 μg/well Pep7 1.25 μg/well Pep8 2.5 μg/well Pep9 1.25 μg/well Salles, B.C.S. et al ., 2017 [ 62 ] A3 Molecular technique (VL patients); parasitology, molecular technique (TL patients) Phage-ELISA 1.00E+08 phages/well II VL Brazil L. infantum …”

“…In all, 57 peptides were derived from 24 different proteins with identified accessions ( Table 2 ) such as leishmanolysin (gp63) [ 35 ], amastin [ 69 ], HSP83.1 [ 42 ], A2, LACK, NH [ 17 ], Histone H1 [ 10 ], β-tubulin [ 16 ] or tryparedoxin [ 40 , 70 ]. For the remaining 20 peptides, the protein was not known or was not identified (identification number (ID UniProt ( https://www.uniprot.org/ ) or NCBI accession number ( https://www.ncbi.nlm.nih.gov/protein/ ) are not specified) [ 15 , 17 , 58 , 62 ]. Most peptides published in this review were derived from four species of Leishmania .…”

Immunoproteomics and phage display in the context of leishmaniasis complexity

“…Two selected clones were then tested in immunization protocols in BALB/c mice, and protection against L. amazonensis infection was achieved, with significant reductions in the parasite load and footpad swelling. In another study, Ramos et al (63) selected nine mimotopes using sera from VL and VL/HIV patients in the biopanning cycles. The corresponding epitopes were produced as synthetic peptides and evaluated using an ELISA against a human serological panel.…”

“…In another study, Ramos et al. ( 63 ) selected nine mimotopes using sera from VL and VL/HIV patients in the biopanning cycles. The corresponding epitopes were produced as synthetic peptides and evaluated using an ELISA against a human serological panel.…”