Development of a novel ddPCR assay for the simultaneous detection of the protozoan parasites Leishmania infantum and Leishmania tarentolae

Abstract Background Leishmaniases, caused by protozoan parasites of the genus Leishmania, are vector-borne diseases occurring mainly in the tropics and subtropics of the world, as well as in the Mediterranean Basin. In this area, the mammalian pathogen Leishmania infantum is endemic, along with the...

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Main Authors: Alessandro Alvaro, Giulia Maria Cattaneo, Ilaria Varotto-Boccazzi, Riccardo Molteni, Jairo Alfonso Mendoza-Roldan, Matteo Brilli, Matilde Silvia Conconi, Virginia Giovagnoli, Alessandro Manenti, Domenico Otranto, Claudio Bandi, Sara Epis
Format: Article
Language:English
Published: BMC 2025-07-01
Series:Parasites & Vectors
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Online Access:https://doi.org/10.1186/s13071-025-06871-3
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author Alessandro Alvaro
Giulia Maria Cattaneo
Ilaria Varotto-Boccazzi
Riccardo Molteni
Jairo Alfonso Mendoza-Roldan
Matteo Brilli
Matilde Silvia Conconi
Virginia Giovagnoli
Alessandro Manenti
Domenico Otranto
Claudio Bandi
Sara Epis
author_facet Alessandro Alvaro
Giulia Maria Cattaneo
Ilaria Varotto-Boccazzi
Riccardo Molteni
Jairo Alfonso Mendoza-Roldan
Matteo Brilli
Matilde Silvia Conconi
Virginia Giovagnoli
Alessandro Manenti
Domenico Otranto
Claudio Bandi
Sara Epis
author_sort Alessandro Alvaro
collection DOAJ
description Abstract Background Leishmaniases, caused by protozoan parasites of the genus Leishmania, are vector-borne diseases occurring mainly in the tropics and subtropics of the world, as well as in the Mediterranean Basin. In this area, the mammalian pathogen Leishmania infantum is endemic, along with the reptile-associated Leishmania tarentolae. The two species occur in sympatry, and there is evidence that the exposure to L. tarentolae in mammalian hosts may elicit a protective immune response towards pathogenic Leishmania species. Accurate detection methods for both species are therefore crucial for gathering comprehensive information on the epidemiology of leishmaniases. In microbiological diagnosis, limits in detection performance imply the risk of false negatives and other issues, which highlights the need for sensitive methods. Methods Here, we developed a droplet digital polymerase chain reaction assay targeting the kinetoplast minicircle DNA, for the simultaneous and differential detection of L. infantum and L. tarentolae. The assay features primers designed to bind to both species and species-specific probes. The assay was validated on three cultured isolates for each species, whose cells were spiked into Leishmania-negative dog blood, and on Leishmania-positive sand flies. Sensitivity was assessed with testing serial dilutions, and specificity was evaluated by assessing the cross-reactivity of the probes with the controls of Leishmania-free dog blood and male sand fly DNA. Results The assay demonstrated high sensitivity, with a limit of detection corresponding to one Leishmania cell in the reaction mix for isolates of both L. infantum and L. tarentolae. Limited cross-reaction of the L. tarentolae-targeting probe was observed on L. infantum isolates. No cross-reaction was observed with the controls of Leishmania-free dog blood and male sand flies. Conclusions The protocol can represent a valuable method for comprehensive surveillance in both canine hosts and sand flies in areas in which L. infantum and L. tarentolae occur in sympatry. Graphical Abstract
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spelling doaj-art-bd39b14fd5064d3fb43faa94098ff7aa2025-08-20T03:37:28ZengBMCParasites & Vectors1756-33052025-07-0118111310.1186/s13071-025-06871-3Development of a novel ddPCR assay for the simultaneous detection of the protozoan parasites Leishmania infantum and Leishmania tarentolaeAlessandro Alvaro0Giulia Maria Cattaneo1Ilaria Varotto-Boccazzi2Riccardo Molteni3Jairo Alfonso Mendoza-Roldan4Matteo Brilli5Matilde Silvia Conconi6Virginia Giovagnoli7Alessandro Manenti8Domenico Otranto9Claudio Bandi10Sara Epis11Department of Biosciences, University of MilanDepartment of Biosciences, University of MilanDepartment of Biosciences, University of MilanDepartment of Biosciences, University of MilanDepartment of Veterinary Medicine, University of BariDepartment of Biosciences, University of MilanDepartment of Biosciences, University of MilanDepartment of Biosciences, University of MilanVisMederi SrlDepartment of Veterinary Medicine, University of BariDepartment of Biosciences, University of MilanDepartment of Biosciences, University of MilanAbstract Background Leishmaniases, caused by protozoan parasites of the genus Leishmania, are vector-borne diseases occurring mainly in the tropics and subtropics of the world, as well as in the Mediterranean Basin. In this area, the mammalian pathogen Leishmania infantum is endemic, along with the reptile-associated Leishmania tarentolae. The two species occur in sympatry, and there is evidence that the exposure to L. tarentolae in mammalian hosts may elicit a protective immune response towards pathogenic Leishmania species. Accurate detection methods for both species are therefore crucial for gathering comprehensive information on the epidemiology of leishmaniases. In microbiological diagnosis, limits in detection performance imply the risk of false negatives and other issues, which highlights the need for sensitive methods. Methods Here, we developed a droplet digital polymerase chain reaction assay targeting the kinetoplast minicircle DNA, for the simultaneous and differential detection of L. infantum and L. tarentolae. The assay features primers designed to bind to both species and species-specific probes. The assay was validated on three cultured isolates for each species, whose cells were spiked into Leishmania-negative dog blood, and on Leishmania-positive sand flies. Sensitivity was assessed with testing serial dilutions, and specificity was evaluated by assessing the cross-reactivity of the probes with the controls of Leishmania-free dog blood and male sand fly DNA. Results The assay demonstrated high sensitivity, with a limit of detection corresponding to one Leishmania cell in the reaction mix for isolates of both L. infantum and L. tarentolae. Limited cross-reaction of the L. tarentolae-targeting probe was observed on L. infantum isolates. No cross-reaction was observed with the controls of Leishmania-free dog blood and male sand flies. Conclusions The protocol can represent a valuable method for comprehensive surveillance in both canine hosts and sand flies in areas in which L. infantum and L. tarentolae occur in sympatry. Graphical Abstracthttps://doi.org/10.1186/s13071-025-06871-3Droplet digital PCRLeishmania infantumLeishmania tarentolaeLeishmaniasisEpidemiologySand flies
spellingShingle Alessandro Alvaro
Giulia Maria Cattaneo
Ilaria Varotto-Boccazzi
Riccardo Molteni
Jairo Alfonso Mendoza-Roldan
Matteo Brilli
Matilde Silvia Conconi
Virginia Giovagnoli
Alessandro Manenti
Domenico Otranto
Claudio Bandi
Sara Epis
Development of a novel ddPCR assay for the simultaneous detection of the protozoan parasites Leishmania infantum and Leishmania tarentolae
Parasites & Vectors
Droplet digital PCR
Leishmania infantum
Leishmania tarentolae
Leishmaniasis
Epidemiology
Sand flies
title Development of a novel ddPCR assay for the simultaneous detection of the protozoan parasites Leishmania infantum and Leishmania tarentolae
title_full Development of a novel ddPCR assay for the simultaneous detection of the protozoan parasites Leishmania infantum and Leishmania tarentolae
title_fullStr Development of a novel ddPCR assay for the simultaneous detection of the protozoan parasites Leishmania infantum and Leishmania tarentolae
title_full_unstemmed Development of a novel ddPCR assay for the simultaneous detection of the protozoan parasites Leishmania infantum and Leishmania tarentolae
title_short Development of a novel ddPCR assay for the simultaneous detection of the protozoan parasites Leishmania infantum and Leishmania tarentolae
title_sort development of a novel ddpcr assay for the simultaneous detection of the protozoan parasites leishmania infantum and leishmania tarentolae
topic Droplet digital PCR
Leishmania infantum
Leishmania tarentolae
Leishmaniasis
Epidemiology
Sand flies
url https://doi.org/10.1186/s13071-025-06871-3
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