The development of sexual stage malaria gametocytes in a Wave Bioreactor

Corine G Demanga,Alice Butterworth,Alison Roth,John P Dalton,Jenny W L Eng,John H Adams,Katharine R Trenholme,Donald L Gardiner

doi:10.1186/s13071-017-2155-z

Abstract

BackgroundBlocking malaria gametocyte development in RBCs or their fertilization in the mosquito gut can prevent infection of the mosquito vector and passage of disease to the human host. A ‘transmission blocking’ strategy is a component of future malaria control. However, the lack of robust culture systems for producing large amounts of Plasmodium falciparum gametocytes has limited our understanding of sexual-stage malaria biology and made vaccine or chemotherapeutic discoveries more difficult.MethodsThe Wave BioreactorTM 20/50 EHT culture system was used to develop a convenient and low-maintenance protocol for inducing commitment of P. falciparum parasites to gametocytogenesis. Culture conditions were optimised to obtain mature stage V gametocytes within 2 weeks in a large-scale culture of up to a 1 l.ResultsWe report a simple method for the induction of gametocytogenesis with N-acetylglucosamine (10 mM) within a Wave Bioreactor. By maintaining the culture for 14–16 days as many as 100 million gametocytes (stage V) were produced in a 1 l culture. Gametocytes isolated using magnetic activated cell sorting (MACS) columns were frozen in aliquots for storage. These were revitalised by thawing and shown to retain their ability to exflagellate and infect mosquitoes (Anopheles stephansi).ConclusionsThe production of gametocytes in the Wave Bioreactor under GMP-compliant conditions will not only facilitate cellular, developmental and molecular studies of gametocytes, but also the high-throughput screening for new anti-malarial drugs and, possibly, the development of whole-cell gametocyte or sporozoite-based vaccines.

Highlights

Blocking malaria gametocyte development in red blood cells (RBCs) or their fertilization in the mosquito gut can prevent infection of the mosquito vector and passage of disease to the human host
Gametocytes develop through five distinct stages, with only mature stage V parasites able to undergo sexual reproduction when ingested by a feeding mosquito [3,4,5]
We described the large-scale production of asexual blood stage P. falciparum cultures in the Wave BioreactorTM 20/50 EHT system [27], which is a closed sterile plastic bioreactor that rocks on a heated platform

Summary

Introduction

Blocking malaria gametocyte development in RBCs or their fertilization in the mosquito gut can prevent infection of the mosquito vector and passage of disease to the human host. The lack of robust culture systems for producing large amounts of Plasmodium falciparum gametocytes has limited our understanding of sexual-stage malaria biology and made vaccine or chemotherapeutic discoveries more difficult. The life-cycle of P. falciparum parasites is complex and occurs within two hosts, the human and the female Anopheles mosquito [2]. Gametocytes develop through five distinct stages, with only mature stage V parasites able to undergo sexual reproduction when ingested by a feeding mosquito [3,4,5]. The microgametes and macrogametes of P. falciparum emerge from the ingested RBCs in the mosquito gut where fertilization occurs and results in the formation of a motile ookinete. The ookinete develops into an oocyst containing sporozoites that subsequently migrate to the mosquito salivary glands where they become fully

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Conclusion