Leba Louis-Jérôme, Musset Lise, Pelleau Stéphane, Estevez Yannick, Birer Caroline, Briolant Sébastien, Witkowski Benoit, Ménard Didier, Delves Michael J, Legrand Eric, Duplais Christophe, Popovici Jean
Laboratoire de Parasitologie, Institut Pasteur de la Guyane, Cayenne, French Guiana, France.
Laboratoire ECOFOG (Ecology of Guiana Forests) UMR8172 CNRS-INRA-CIRAD-AgroParisTech-Université des Antilles-Université de la Guyane, French Guiana, France.
Malar J. 2015 Jun 4;14:234. doi: 10.1186/s12936-015-0752-x.
A major requirement for malaria elimination is the development of transmission-blocking interventions. In vitro transmission-blocking bioassays currently mostly rely on the use of very few Plasmodium falciparum reference laboratory strains isolated decades ago. To fill a piece of the gap between laboratory experimental models and natural systems, the purpose of this work was to determine if culture-adapted field isolates of P. falciparum are suitable for in vitro transmission-blocking bioassays targeting functional maturity of male gametocytes: exflagellation.
Plasmodium falciparum isolates were adapted to in vitro culture before being used for in vitro gametocyte production. Maturation was assessed by microscopic observation of gametocyte morphology over time of culture and the functional viability of male gametocytes was assessed by microscopic counting of exflagellating gametocytes. Suitability for in vitro exflagellation-blocking bioassays was determined using dihydroartemisinin and methylene blue.
In vitro gametocyte production was achieved using two isolates from French Guiana and two isolates from Cambodia. Functional maturity of male gametocytes was assessed by exflagellation observations and all four isolates could be used in exflagellation-blocking bioassays with adequate response to methylene blue and dihydroartemisinin.
This work shows that in vitro culture-adapted P. falciparum field isolates of different genetic background, from South America and Southeast Asia, can successfully be used for bioassays targeting the male gametocyte to gamete transition, exflagellation.
疟疾消除的一项主要要求是开发传播阻断干预措施。目前，体外传播阻断生物测定大多依赖于使用几十年前分离的极少数恶性疟原虫参考实验室菌株。为了填补实验室实验模型与自然系统之间的空白，本研究的目的是确定适应培养的恶性疟原虫野外分离株是否适用于针对雄配子体功能成熟（即：出丝）的体外传播阻断生物测定。
恶性疟原虫分离株在用于体外配子体生产之前先适应体外培养。通过显微镜观察培养过程中配子体形态随时间的变化来评估成熟度，通过显微镜计数出丝的配子体来评估雄配子体的功能活力。使用双氢青蒿素和亚甲蓝来确定体外出丝阻断生物测定的适用性。
使用来自法属圭亚那的两个分离株和来自柬埔寨的两个分离株实现了体外配子体生产。通过出丝观察评估雄配子体的功能成熟度，所有四个分离株均可用于出丝阻断生物测定，且对亚甲蓝和双氢青蒿素有充分反应。
本研究表明，来自南美洲和东南亚、具有不同遗传背景、适应体外培养的恶性疟原虫野外分离株可成功用于针对雄配子体向配子转变（即出丝）的生物测定。
