Multi-center screening of the Pathogen Box collection for schistosomiasis drug discovery

Martina Maccesi,Valérian Pasche,Pedro H N Aguiar,Ruben Abagyan,Sandro Montefusco,Marina M Mourão,Jennifer Keiser,Melody Padilla,Conor R Caffrey,Brian M Suzuki

doi:10.1186/s13071-019-3747-6

Abstract

BackgroundOver the past five years, as a public service to encourage and accelerate drug discovery for diseases of poverty, the Medicines for Malaria Venture (MMV) has released box sets of 400 compounds named the Malaria, Pathogen and Stasis Boxes. Here, we screened the Pathogen Box against the post-infective larvae (schistosomula) of Schistosoma mansoni using assays particular to the three contributing institutions, namely, the University of California San Diego (UCSD) in the USA, the Swiss Tropical and Public Health Institute (Swiss TPH) in Switzerland, and the Fundação Oswaldo Cruz (FIOCRUZ) in Brazil. With the same set of compounds, the goal was to determine the degree of inter-assay variability and identify a core set of active compounds common to all three assays. New drugs for schistosomiasis would be welcome given that current treatment and control strategies rely on chemotherapy with just one drug, praziquantel.MethodsBoth the UCSD and Swiss TPH assays utilize daily observational scoring methodologies over 72 h, whereas the FIOCRUZ assay employs XTT (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide) at 72 h to measure viability as a function of NAD+/NADH redox state. Raw and transformed data arising from each assay were assembled for comparative analysis.ResultsFor the UCSD and Swiss TPH assays, there was strong concordance of at least 87% in identifying active and inactive compounds on one or more of the three days. When all three assays were compared at 72 h, concordance remained a robust 74%. Further, robust Pearsonʼs correlations (0.48–0.68) were measured between the assays. Of those actives at 72 h, the UCSD, Swiss TPH and FIOCRUZ assays identified 86, 103 and 66 compounds, respectively, of which 35 were common. Assay idiosyncrasies included the identification of unique compounds, the differential ability to identify known antischistosomal compounds and the concept that compounds of interest might include those that increase metabolic activity above baseline.ConclusionsThe inter-assay data generated were in good agreement, including with previously reported data. A common set of antischistosomal molecules for further exploration has been identified.

Highlights

Over the past five years, as a public service to encourage and accelerate drug discovery for diseases of poverty, the Medicines for Malaria Venture (MMV) has released box sets of 400 compounds named the Malaria, Pathogen and Stasis Boxes
Active and inactive Pathogen Box compounds identified among the three institutions Schistosoma mansoni schistosomula were screened with the 400 constituent compounds of the MMV Pathogen Box by three institution-specific assays developed by University of California San Diego (UCSD), the Swiss Swiss Tropical and Public Health Institute (TPH) and Fundação Oswaldo Cruz (FIOCRUZ)
Our study is relevant as, to date, a plethora of schistosomula screening assays employing different methodologies (e.g. adenosine triphosphate (ATP) and NAD(P) metabolic indicators, deoxyribonucleic acid (DNA) intercalation agents such as propidium iodide, and visual- or automated image-based systems) and readouts, have been developed such that the general interpretability of data may be constrained by the particular assay employed [9,10,11, 24, 28, 32,33,34]

Summary

Introduction

Over the past five years, as a public service to encourage and accelerate drug discovery for diseases of poverty, the Medicines for Malaria Venture (MMV) has released box sets of 400 compounds named the Malaria, Pathogen and Stasis Boxes. Unlike the case for other global infectious diseases of poverty, schistosomiasis has lacked the prioritization necessary to establish trans-national, public-private drug development programmes that support the synthesis of small molecule chemical libraries, high throughput screening systems and the discovery expertise to identify and advance compounds to the clinic. Allied to this is the greater difficulty, logistics and costs needed to maintain and handle the schistosome parasite compared to the self-replicative single-celled organisms like malaria or the kinetoplastid parasites that are relatively easy to culture and amenable to automated liquid handling robotics. Schistosome drug discovery remains fragmented across the academic sector with its more limited resources

Methods

Results

Conclusion