Immunogenicity, Leishmaniasis, Leishmaniasis, Cutaneous, Leishmaniasis, Visceral
Conditions
Keywords
leishmania vaccine candidate antigens, leishmania vaccine, leishmaniasis vaccine
Brief summary
This study assesses the immunoprevalence (presence of the induced T-cell response across different patients (and thus HLA types) of six prioritized IPX-derived Leishmania antigens, using Good Laboratory Practice-grade soluble Leishmania antigen (GLP-SLA) as a positive control. Longitudinal GLP-SLA stimulation validates its IFN-γ release assay performance to support licensing of a QuantiFERON-like test (Leish-IGRA) for treatment monitoring. IPX-derived Leishmania antigen screening focuses on day 0 and EOT, while GLP-SLA includes all timepoints. Induced T-cell responses by ex vivo stimulation of blood and tissue samples (lesion, bone marrow, or spleen) from patients with cutaneous and visceral leishmaniasis (two-centre cohort) before and after treatment will be verified. Samples from Ethiopian 'non-infected' healthy volunteers will be included in parallel to differentiate from Leishmania antigen-specific versus aspecific T-cell activation. The induced T-cell response will mainly be determined by the expressed IFN-γ levels after stimulation. Additional analyses are included to further characterize the activation and cytokine profiles of these IPX-derived Leishmania antigen-specific T-cells, while the breadth of the T-cell response will be determined by mapping the response across different patients (and thus different HLA types).
Detailed description
Despite decades of effort, to date, there is no licensed vaccine for human leishmaniasis. For subunit vaccine development, candidate antigens were mostly identified through in silico predictions or animal experimental models, and their immunogenicity, while promising in these systems, did not translate into sufficiently or consistently induced T-cell responses in humans. To address this gap, the Institute of Tropical Medicine Antwerp (ITM) has recently applied a sensitive immunopeptidomics method (IPX) to directly identify naturally processed and MHC-presented Leishmania epitopes from tissue samples of patients with cutaneous leishmaniasis (CL). These epitopes, and their source antigens, represent clinically relevant human-derived vaccine candidate targets. This study assesses the immunoprevalence (presence of the induced T-cell response across different patients (and thus HLA types) of six prioritized IPX-derived Leishmania antigens, using Good Laboratory Practice-grade soluble Leishmania antigen (GLP-SLA) as a positive control. Longitudinal GLP-SLA stimulation validates its IFN-γ release assay performance to support licensing of a QuantiFERON-like test (Leish-IGRA) for treatment monitoring. IPX-derived Leishmania antigen screening focuses on day 0 and EOT, while GLP-SLA includes all timepoints. Induced T-cell responses by ex vivo stimulation of blood and tissue samples (lesion, bone marrow, or spleen) from patients with cutaneous and visceral leishmaniasis (two-centre cohort) before and after treatment will be verified. Samples from Ethiopian 'non-infected' healthy volunteers will be included in parallel to differentiate from Leishmania antigen-specific versus aspecific T-cell activation. The induced T-cell response will mainly be determined by the expressed IFN-γ levels after stimulation. Additional analyses are included to further characterize the activation and cytokine profiles of these IPX-derived Leishmania antigen-specific T-cells, while the breadth of the T-cell response will be determined by mapping the response across different patients (and thus different HLA types).
Interventions
None listed
Sponsors
Institute of Tropical Medicine, Belgium
Universiteit Antwerpen
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
1. VL and CL patients INCLUSION CRITERIA: * Aged 18-65 years To minimize variability within this first study to verify induced T-cell responses specifically towards vaccine candidate target antigens/peptide pools, we focus on more robust adult immune responses. Children and elderly are vulnerable populations with divergent immune responses and are therefore excluded. * Suspected diagnosis of VL or CL, defined as: * VL: Clinically suspected VL presentation (e.g., prolonged fever, splenomegaly) * CL: Clinically suspected lesions (e.g., nodular, ulcerative, or plaque-like lesions) Including suspected VL and CL patients was done in earlier VL and CL studies (Clinicaltrials.gov Identifier: NCT05602610 and NCT05332093, \>95% of suspected cohort confirmed to have VL or CL, respectively) to facilitate efficient recruitment flow for both the patient as the study team. * Willing and able to provide informed consent Ensures autonomy and understanding, allowing participants to fully understand their risks and benefits, and the possibility to withdraw at any time without affecting care.
Exclusion criteria
* Are currently enrolled in another interventional clinical study * Have known severe comorbidities (e.g., autoimmune disease, HIV, tuberculosis, leprosy, or malaria) * Have known pregnancy * Cognitively impaired individuals * Have received immunosuppressive drugs in the past month * Have received a vaccine in the past month * Have received modern antileishmanial treatment in the past month * Are on anticoagulation medication or have bleeding disorders that would contraindicate safe blood or tissue sampling * For CL patients: * Primary lesion size \< 2 cm * Too difficult or too painful sampling zone (e.g., close to the mucosa or lymphatic system, on joints, eyelid or ear) * Not eligible for systemic SSG treatment 2. Ethiopian 'non-infected' healthy volunteers INCLUSION CRITERIA: * Aged 18-65 years Matching the age range of VL and CL patients * Resides in Addis Ababa An uninfected control group is included to distinguish true antigen-specific T-cell responses from non-specific (background) T-cell activation. This control group should ideally consist of healthy individuals without prior symptomatic or asymptomatic exposure to Leishmania, as previous (unknown) asymptomatic infections could lead to detectable Leishmania-specific T-cell responses and thus confound background baseline measurements. To minimize this risk, we will recruit healthy volunteers from 'non-infected' areas, specifically the Addis Ababa region, and apply strict (retrospective)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| To determine the immunoprevalence of IPX-derived Leishmania antigens and their combinations in Ethiopian patients with VL and CL. | "Day 0" (baseline) until "Day 17" or "Day 28" (end of treatment, may vary due to treatment) | Proportion of patients that demonstrate an induced T-cell response (represented by IFN-γ expression) after ex vivo stimulation of IPX-derived antigens Leishmania and combinations. |
Secondary
| Measure | Time frame |
|---|---|
| To further characterize the phenotype (e.g., flow cytometry, single-cell sequencing) and polyfunctionality (multiplex cytokine determination) of the induced T-cell response after ex vivo stimulation with IPX-derived Leishmania antigens and GLP-SLA | "Day 0" (baseline) until "Day 17" or "Day 28" (end of treatment, may vary due to treatment) |
| To compare the induced T-cell response of IPX-derived Leishmania antigens with GLP-SLA in blood versus tissues, by clinical presentation | "Day 0" (baseline) until "Day 17" or "Day 28" (end of treatment, may vary due to treatment) |
| To determine the dynamics of the induced T-cell response of IPX-derived Leishmania antigens versus GLP-SLA before and at end of successful versus failed treatment | "Day 0" (baseline) until "Day 17" or "Day 28" (end of treatment, may vary due to treatment) |
| To assess the predictive value of the Leish-IGRA for treatment outcome in CL and VL patients before, during and at end of treatment | "Day 0" (baseline), "Day 7", until "Day 17" or "Day 28" (end of treatment, may vary due to treatment) |
| To characterize the HLA-TCR interactions involved in the recognition of IPX-derived Leishmania antigens through TCR sequencing and HLA typing | "Day 0" (baseline) until "Day 17" or "Day 28" (end of treatment, may vary due to treatment) |
Countries
Ethiopia
Contacts
CONTACTEshetu Molla, PhD
CONTACTThao-Thy Pham, PhD
PRINCIPAL_INVESTIGATORThao-Thy Pham
Institute of Tropical Medicine Antwerp
PRINCIPAL_INVESTIGATORWim Adriaensen, PhD
Institute of Tropical Medicine Antwerp
PRINCIPAL_INVESTIGATOREshetu Molla, PhD
Armauer Hansen Research Institute, Ethiopia
PRINCIPAL_INVESTIGATOREndalamaw Gadisa, PhD
Armauer Hansen Research Institute, Ethiopia
Outcome results
None listed