Receptor-Ligand Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia.
PhD Programme in Biomedical and Biological Sciences, Universidad del Rosario, Bogotá, Colombia.
Malar J. 2020 Feb 3;19(1):57. doi: 10.1186/s12936-020-3142-y.
The epidemiological control of malaria has been hampered by the appearance of parasite resistance to anti-malarial drugs and by the resistance of mosquito vectors to control measures. This has also been associated with weak transmission control, mostly due to poor control of asymptomatic patients associated with host-vector transmission. This highlights the importance of studying the parasite's sexual forms (gametocytes) which are involved in this phase of the parasite's life-cycle. Some African and Asian strains of Plasmodium falciparum have been fully characterized regarding sexual forms' production; however, few Latin-American strains have been so characterized. This study was aimed at characterizing the Colombian FCB2 strain as a gametocyte producer able to infect mosquitoes.
Gametocyte production was induced in in vitro cultured P. falciparum FCB2 and 3D7 strains. Pfap2g and Pfs25 gene expression was detected in FCB2 strain gametocyte culture by RT-PCR. Comparative analysis of gametocytes obtained from both strains was made (counts and morphological changes). In vitro zygote formation from FCB2 gametocytes was induced by incubating a gametocyte culture sample at 27 °C for 20 min. A controlled Anopheles albimanus infection was made using an artificial feed system with cultured FCB2 gametocytes (14-15 days old). Mosquito midgut dissection was then carried out for analyzing oocysts.
The FCB2 strain expressed Pfap2g, Pfs16, Pfg27/25 and Pfs25 sexual differentiation-related genes after in vitro sexual differentiation induction, producing gametocytes that conserved the expected morphological features. The amount of FCB2 gametocytes produced was similar to that from the 3D7 strain. FCB2 gametocytes were differentiated into zygotes and ookinetes after an in vitro low-temperature stimulus and infected An. albimanus mosquitoes, developing to oocyst stage.
Even with the history of long-term FCB2 strain in vitro culture maintenance, it has retained its sexual differentiation ability. The gametocytes produced here preserved these parasite forms' usual characteristics and An. albimanus infection capability, thus enabling its use as a tool for studying sexual form biology, An. albimanus infection comparative analysis and anti-malarial drug and vaccine development.
抗疟药物的寄生虫耐药性和蚊子传播媒介对控制措施的耐药性阻碍了疟疾的流行病学控制。这也与弱传播控制有关，主要是由于对与宿主-媒介传播相关的无症状患者的控制不佳。这突出表明研究寄生虫的有性形式（配子体）的重要性，这些有性形式与寄生虫生命周期的这一阶段有关。一些非洲和亚洲的恶性疟原虫菌株已经完全表征了有性形式的产生；然而，很少有拉丁美洲的菌株得到如此表征。本研究旨在将哥伦比亚 FCB2 菌株表征为能够感染蚊子的配子体产生者。
在体外培养的恶性疟原虫 FCB2 和 3D7 菌株中诱导配子体产生。通过 RT-PCR 检测 FCB2 株配子体培养物中 Pfap2g 和 Pfs25 基因的表达。对来自两种菌株的配子体进行比较分析（计数和形态变化）。通过在 27°C 下孵育配子体培养物样本 20 分钟，从 FCB2 配子体中诱导体外合子形成。使用带有培养的 FCB2 配子体的人工饲料系统进行受控的按蚊感染。然后进行蚊子中肠解剖以分析卵囊。
FCB2 株在体外有性分化诱导后表达 Pfap2g、Pfs16、Pfg27/25 和 Pfs25 性分化相关基因，产生保留预期形态特征的配子体。FCB2 株产生的配子体数量与 3D7 株相似。FCB2 配子体在体外低温刺激下分化为合子和动合子，并感染按蚊，发育至卵囊阶段。
即使 FCB2 株在体外长期培养维持的历史，它仍保留其有性分化能力。这里产生的配子体保留了这些寄生虫形式的通常特征和按蚊感染能力，从而使其能够用作研究有性形式生物学、按蚊感染比较分析和抗疟药物和疫苗开发的工具。
