Phenotypic screening techniques forCryptosporidiumdrug discovery

Abstract

Introduction: Two landmark epidemiological studies identified Cryptosporidium spp. as a significant cause of diarrheal disease in pediatric populations in resource-limited countries. Notably, nitazoxanide is the only approved drug for treatment of cryptosporidiosis but shows limited efficacy. As a result, many drug discovery efforts have commenced to find improved treatments. The unique biology of Cryptosporidium presents challenges for traditional drug discovery methods, which has inspired new assay platforms to study parasite biology and drug screening. Areas covered: The authors review historical advancements in phenotypic-based assays and techniques for Cryptosporidium drug discovery, as well as recent advances that will define future drug discovery. The reliance on phenotypic-based screens and repositioning of phenotypic hits from other pathogens has quickly created a robust pipeline of potential cryptosporidiosis therapeutics. The latest advances involve new in vitro culture methods for oocyst generation, continuous culturing capabilities, and more physiologically relevant assays for testing compounds. Expert opinion: Previous phenotypic screening techniques have laid the groundwork for recent cryptosporidiosis drug discovery efforts. The resulting improved methodologies characterize compound activity, identify, and validate drug targets, and prioritize new compounds for drug development. The most recent improvements in phenotypic assays are poised to help advance compounds into clinical development.

Opportunities and Challenges in Developing a Cryptosporidium Controlled Human Infection Model for Testing Antiparasitic Agents

“… 24 , 25 Some of the promising NCEs include Cryptosporidium calcium-dependent protein kinase 1 (CpCDPK1) inhibitors, 26 phosphatidylinositol-4-OH kinase (PI(4)K) inhibitors, 27 piperazine-based lead compound MMV665917, 16 lysyl-tRNA synthetase (KRS) inhibitors, 28 oxaboroles that are a cleavage and polyadenylation specificity factor3 inhibitors, 29 , 30 bicyclic azetidines that are phenylalanyl-tRNA synthetase inhibitors, 31 methionyl-tRNA synthetase inhibitors, 32 a choline-based phospholipid VB-201, 33 and multiple novel cell-active hits. 34 Most of these NCEs have demonstrated antiparasitic activity against both C . parvum and C .…”

High-throughput phenotypic screening of the human spermatozoon

“…Phenotypic screening is a common approach in drug discovery (Gilbert 2013, Moffat, et al 2017 and has been successfully used to discover several new compounds for major disorders and diseases e.g. fragile X syndrome (Kaufmann, et al 2015), hepatitis C (Gao, et al 2010), cryptosporidiosis (Jumani, et al 2019, Love, et al 2017, Love and McNamara 2021), and malaria (Antonova-Koch, et al 2018, Baragaña, et al 2015, Baragaña, et al 2016. In addition to identifying potential drug candidates, phenotypic screening can provide insights to improving the understanding of biology of the cells or complex model systems in normal or diseased states, by identifying novel, chemical tools (Moffat, et al 2017).…”

Emerging treatment options for cryptosporidiosis

“…Phenotypic screens are less biased and not dependent on a known target, and several emerging therapeutics for cryptosporidiosis were discovered from screening compound collections with known activity in other pathogens against Cryptosporidium spp. [ 25 ]. Phenotypic screens may identify compounds with novel targets or pathways, with the caveat that target identification and MoA studies are often needed after active compounds are discovered.…”

“…Phenotypic screens may identify compounds with novel targets or pathways, with the caveat that target identification and MoA studies are often needed after active compounds are discovered. There have been a number of additional phenotypic screens for Cryptosporidium drug discovery [ 25 , 26 ], though the compounds discussed in this review are the most advanced.…”