A rotifer-derived paralytic compound prevents transmission of schistosomiasis to a mammalian host.

Jiarong Gao,Peter Yau,Fred A Lewis,Phillip A Newmark,Ning Yang,Jonathan V Sweedler,James J Collins,Chaitan Khosla

doi:10.1371/journal.pbio.3000485

Abstract

Schistosomes are parasitic flatworms that infect over 200 million people, causing the neglected tropical disease, schistosomiasis. A single drug, praziquantel, is used to treat schistosome infection. Limitations in mass drug administration programs and the emergence of schistosomiasis in nontropical areas indicate the need for new strategies to prevent infection. It has been known for several decades that rotifers colonizing the schistosome's snail intermediate host produce a water-soluble factor that paralyzes cercariae, the life cycle stage infecting humans. In spite of its potential for preventing infection, the nature of this factor has remained obscure. Here, we report the purification and chemical characterization of Schistosome Paralysis Factor (SPF), a novel tetracyclic alkaloid produced by the rotifer Rotaria rotatoria. We show that this compound paralyzes schistosome cercariae and prevents infection and does so more effectively than analogous compounds. This molecule provides new directions for understanding cercariae motility and new strategies for preventing schistosome infection.

Highlights

Schistosomiasis—caused by parasitic flatworms of the genus Schistosoma—is a major neglected tropical disease, affecting over 200 million people, with over 700 million people at risk of infection [1,2,3]
To identify which rotifer was responsible for the paralytic effect, we grew clonal isolates of each species, producing rotifer-conditioned artificial pond water (APW)
Adding R. rotatoria-conditioned APW to freshly collected cercariae resulted in gradual paralysis within 5 min (Fig 1D)

Summary

Introduction

Schistosomiasis—caused by parasitic flatworms of the genus Schistosoma—is a major neglected tropical disease, affecting over 200 million people, with over 700 million people at risk of infection [1,2,3].

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Conclusion