VALIDATE Workshop: Vaccines for Neglected Tropical Skin Diseases – Progress and Challenges
Workshop Report

From 6–8 May 2025, the VALIDATE Network hosted a closed workshop in Bogotá, Colombia, bringing together 28 invited delegates to tackle one of global health’s more overlooked challenges: vaccine development for neglected tropical skin diseases (NTDs). Held at the elegant Museo El Chicó, the workshop focused on leishmaniasis, Buruli ulcer, leprosy, and cutaneous tuberculosis—diseases which share common immunological features but are often sidelined in global vaccine R&D.
Day One: Introductions
Dr Maria Adelaida Gomez opened the workshop by highlighting the renewed momentum behind skin-NTD research and the potential for collective action. The morning continued with short “Turbo Talks,” during which each delegate introduced themselves, their work, and their expectations for the workshop. The quick-fire talks set a collaborative tone for the rest of the workshop..
The workshop opened with a welcome from Dr Maria Adelaida Gomez (CIDEIM, Colombia), who set the tone for three days of collaborative and interdisciplinary dialogue. The initial session featured “Turbo Talks,” in which all delegates gave short introductions to their work, helping to build connections across a diverse group of attendees and laying the groundwork for meaningful engagement.
The first morning focused on foundational overviews of the four main pathogens. Dr Gomez began with a talk on the wide clinical spectrum of cutaneous leishmaniasis and the challenges this diversity poses for vaccine development. She was followed by Prof Steve Muhi (University of Melbourne, Australia), standing in for Dr Yaw Ampem Amoako (KNUST & KCCR, Ghana), who presented an overview of Buruli ulcer disease and highlighted the shifting epidemiology and lack of vaccine tools. Dr Hua Wang (University of Strathclyde, UK) gave a historical and scientific overview of Mycobacterium leprae, while Prof Rajko Reljic (St George’s University of London, UK) offered a brief presentation on tuberculosis with a focus on its cutaneous forms. These sessions provided a shared knowledge base that would support comparative discussions later in the programme.
The afternoon moved to funders' and organisational perspectives. Dr Sundeep Vedithi (University of Cambridge, UK) discussed the development of point-of-care diagnostics and LepVax, a promising leprosy vaccine candidate. Jeanette Hayes (Wellcome Trust, UK) shared Wellcome’s current investments and future priorities in infectious disease research, with emphasis on TB and leishmaniasis. Luis Calzadilla (British Embassy, Colombia) provided an overview of the UK’s Science and Technology portfolio in Colombia, and Dr Daniel Argaw Dagne (World Health Organization, Switzerland) spoke on the integrated management of skin NTDs and key research gaps. The day concluded with a round-table discussion addressing the role of funders in raising disease awareness, monitoring project impact, prioritising vaccine targets, and forming effective public-private-academic partnerships.

Day Two: Pathogenesis & Vaccines in the Field
Day two focused on pathogenesis, immune mechanisms, and vaccine innovation. The morning began with Dr Fernanda Novais (Ohio State University, USA), who examined how immune responses in cutaneous leishmaniasis can drive tissue damage rather than parasite clearance. Prof Rachel Simmonds (University of Surrey, UK) followed with a talk on the virulence factor mycolactone and its disruptive effects on host cellular physiology in Buruli ulcer. Dr Márcia Rodrigues Jardim (Fiocruz, Brazil) spoke about the pathogenesis of leprosy and the critical importance of early diagnosis, especially in relation to peripheral nerve damage. Prof Adrie Steyn (Africa Health Research Institute, South Africa, and University of Alabama, USA) then presented detailed insights into human TB lesions using cutting-edge spatial transcriptomics and multiplex imaging. These talks were followed by a round-table session that explored shared and divergent immunological mechanisms across the skin NTDs, the role of systems biology, and the potential of interdisciplinary collaboration to advance understanding of host-pathogen dynamics.
The afternoon turned to recent progress in vaccine research. Prof Rajko Reljic presented data from his team’s recent work showing that a composite subunit vaccine conferred full protection against Mycobacterium ulcerans in a mouse model. Dr Camila de Oliveira (Fiocruz, Brazil) discussed the use of attenuated parasites in developing a vaccine for Leishmania braziliensis, while Dr Veronica Schmitz Pereira (Fiocruz, Brazil) reviewed the progress of a leprosy vaccine currently undergoing clinical trials and the challenges of identifying reliable correlates of protection. Round-table discussion topics included the feasibility of cross-protective vaccines, the potential for mRNA technologies in NTD contexts, and the likely impact of climate change on disease spread and research priorities.

Day Three: Modelling and Social Perspectives
The final day opened with a session on laboratory and animal models. Prof Steve Muhi returned to discuss the evolution of Buruli ulcer animal models, including upcoming plans to trial vaccines in native Australian possums. Prof Manabu Ato (National Institute of Infectious Diseases, Japan) explored the limitations of current models for leprosy and the translational efforts underway in his lab. Dr Andres Felipe Vallejo Pulido (University of Southampton, UK) presented on spatial and single-cell transcriptomics as tools for decoding local immune responses and informing antigen selection and delivery system design. The accompanying round-table addressed the future of in vitro and ex vivo systems, how human trial outcomes could be better used to refine models, and whether partially protective vaccines should continue to be pursued.
The final session turned to the social aspects of skin NTD research. Prof Maria Elena Bottazzi (Baylor College of Medicine, USA) offered a framework for integrating vaccine science with economic and policy considerations. Mrs Alexandra Cossio Duque (CIDEIM, Colombia) addressed the logistical and ethical challenges of conducting clinical research in remote rural areas. Dr Maria del Mar Castro Noriega (University of Heidelberg / CIDEIM) discussed the role of qualitative and mixed-methods research in incorporating patient perspectives into product development. Mrs Maria Isabel Echavarria (CIDEIM, Colombia) focused on implementation science and social innovation as tools to translate interventions into real-world impact, and Dr Krishna Lama shared lessons from leprosy control efforts that used community-led models of engagement.
The final round-table discussions focused on incorporating patient perspectives into policy and product development, measuring vaccine impact beyond clinical outcomes, addressing vaccine hesitancy, and ensuring equitable access in low-income settings. Delegates also considered next steps for collaboration, including developing a joint white paper, forming thematic working groups, delivering an online seminar series, or co-authoring a poster for the VALIDATE Annual Meeting.
How delegates described the workshop.

Agenda
0845 – 0900 Registration & Coffee
0900 – 0905 Welcome from Dr Maria Adelaida Gomez
Session 1: Introductions

0905 – 1020 Turbo Talks
All Delegates
1020 – 1050 Break

1050 – 1120 The Cutaneous Leishmaniasis Spectrum and Challenges for Vaccine Development
Prof Maria Adelaida Gomez, CIDEIM, Colombia

1120 – 1150 Overview of Buruli Ulcer Disease
Dr Stephen Muhi, University of Melbourne, Australia (standing in for Dr Yaw Ampem Amoako, KNUSTKCCR, Ghana)
1150 – 1200 Q&A / Panel
1200 – 1300 Lunch

1300 – 1330 Leprosy: What Do We Know About Mycobacterium leprae?
Dr Hua Wang, University of Strathclyde, UK

1330 – 1400 Brief Overview of TB with a Focus on Cutaneous Forms
Prof Rajko Reljic, St George's University of London (SGUL), UK
1400 – 1410 Q&A / Panel
1410 – 1440 Break
Session 2: Funders & Organisation Perspectives

1440 – 1500 Advancements in Point-of-Care Molecular Diagnostics and Vaccine Strategies for Leprosy Diagnosis and Control
Dr Sundeep Vedithi, University of Cambridge, UK

1500 – 1520 Wellcome's Strategic Approach to Infectious Disease Challenges
Miss Jeanette Hayes, Wellcome Trust, UK

1520 – 1540 UK Science & Technology Network in Colombia
Mr Luis Calzadilla, British Embassy, Colombia

1540 – 1600 Integrated Control and Management of Skin NTDs and Priority Research Gaps
Dr Daniel Argaw Dagne, World Health Organization (WHO), Switzerland
1600 – 1620 Q&A / Panel
1620 – 1655 Round-table Discussions
1655 – 1700 Wrap-Up
0845 – 0900 Registration & Coffee
0900 – 0905 Welcome from Dr Maria Adelaida Gomez
0845 – 0900 Coffee
Session 3: Pathogenesis – Mechanisms of Protection, Pathology, Virulence Factors

0900 – 0930 Immunopathogenesis in Cutaneous Leishmaniasis
Dr Fernanda Novais, Ohio State University, USA

0930 – 1000 Inhibition of Sec61 by Mycolactone – A Virulence Mechanism with Major Impacts on Cellular Physiology
Prof Rachel Simmonds, University of Surrey, UK
1000 – 1010 Q&A / Panel
1010 – 1040 Break

1040 – 1110 Leprosy: History, Pathogenesis, and Treatment
Dr Márcia Rodrigues Jardim, Fundação Oswaldo Cruz (Fiocruz), Brazil

1110 – 1140 Unmasking Human Tuberculosis: Insights into Granuloma Biology and Disease Pathogenesis
Prof Adrie Steyn, AHRI & University of Alabama, South Africa & USA
1140 – 1150 Q&A / Panel
1150 – 1230 Round-table Discussions
1230 – 1330 Lunch
Session 4: Latest Vaccine Progress in the Field

1330 – 1400 A Composite Subunit Vaccine Confers Full Protection Against Buruli Ulcer in the Mouse Model
Prof Rajko Reljic, St George's University of London (SGUL), UK

1400 – 1430 Attenuated Parasites as a Road for Vaccine Development Against CL – Roadblocks and Advancements
Dr Camila de Oliveira, Fundação Oswaldo Cruz (Fiocruz), Brazil

1430 – 1500 Advancing Leprosy Vaccines Through Human Immunology: Challenges and New Directions
Dr Veronica Schmitz, Fundação Oswaldo Cruz (Fiocruz), Brazil
1500 – 1515 Q&A / Panel
1515 – 1545 Break
1545 – 1645 Round-table Discussions
1645 – 1700 Wrap-Up
0845 – 0900 Coffee
Session 5: Lab & Animal Models to Study Local Immune Responses and Delivery Systems

0900 – 0930 Buruli Ulcer Vaccine Animal Models: Past, Present and Future Challenges
Prof Steve Muhi, University of Melbourne, Australia

0930 – 1000 Basic and Translational Research for Leprosy: A Long Road to Prevention, Diagnosis, and Therapeutics
Prof Manabu Ato, National Institute of Infectious Diseases (NIID), Japan

1000 – 1030 Spatial & Single Cell Transcriptomics: Decoding Skin Resident Immunity from Melanoma to Mycobacteria
Dr Andres Vallejo, University of Southampton, UK
1030 – 1045 Q&A / Panel
1045 – 1115 Break
1115 – 1200 Round-table Discussions
1200 – 1300 Lunch
Session 6: Social Aspects – Patient Perspectives and Societal Impact

1300 – 1320 Integrating the Vaccine Sciences within Social, Economic, and Policy Perspectives
Prof Maria Elena Botazzi, Baylor College of Medicine, USA

1320 – 1340 The Social Challenges of Clinical Research in Skin NTDs in Remote Rural Areas
Mrs Alexandra Cossio, CIDEIM, Colombia

1340 – 1400 Patient Involvement in Leishmaniasis Product Development: The Role of Qualitative and Mixed Methods
Dr Maria del Mar Castro, University of Heidelberg / CIDEIM

1400 – 1420 Bridging the Gap: From Intervention to Impact Through Implementation Research and Social Innovation
Mrs Maria I Echavarria, CIDEIM, Colombia
1420 – 1500 Q&A / Panel
1500 – 1530 Break
1530 – 1635 Round-table Discussions
1635 – 1700 Wrap-Up