The use of quantitative qRT-PCR assays for detection and quantification of late gametocyte stages has revealed the high transmission capacity of the human malaria parasite, Plasmodium falciparum. To understand how the parasite adjusts its transmission in response to in-host environmental conditions including antimalarials requires simultaneous quantification of early and late gametocytes. Here, we describe qRT-PCR assays that specifically detect and quantify early-stage P. falciparum gametocytes. The assays are based on expression of known early and late gametocyte genes and were developed using purified stage II and stage V gametocytes and tested in natural and controlled human infections. Genes pfpeg4 and pfg27 are specifically expressed at significant levels in early gametocytes with a limit of quantification of 190 and 390 gametocytes/mL, respectively. In infected volunteers, transcripts of pfpeg4 and pfg27 were detected shortly after the onset of blood stage infection. In natural infections, both early (pfpeg4/pfg27) and late gametocyte transcripts (pfs25) were detected in 71.2% of individuals, only early gametocyte transcripts in 12.6%, and only late gametocyte transcripts in 15.2%. The pfpeg4/pfg27 qRT-PCR assays are sensitive and specific for quantification of circulating sexually committed ring stages/early gametocytes and can be used to increase our understanding of epidemiological processes that modulate P. falciparum transmission.

使用定量 qRT-PCR 检测和定量晚期配子体阶段揭示了人类疟原虫恶性疟原虫的高传播能力。要了解寄生虫如何根据宿主环境条件（包括抗疟药）调整其传播，需要同时量化早期和晚期配子体。在这里，我们描述了专门检测和量化早期恶性疟原虫配子体的qRT-PCR 检测。该检测基于已知早期和晚期配子体基因的表达，使用纯化的 II 期和 V 期配子体开发，并在自然和受控人类感染中进行测试。基因pfpeg4和pfg27在早期配子体中以显着水平特异性表达，定量限分别为 190 和 390 个配子体/mL。在受感染的志愿者中，在血液阶段感染开始后不久检测到pfpeg4和pfg27 的转录本。在自然感染中，早期 ( pfpeg4 / pfg27 ) 和晚期配子体转录本(pfs25 ) 在 71.2% 的个体中均被检测到，只有 12.6% 的早期配子体转录本和 15.2% 的晚期配子体转录本。该pfpeg4 / pfg27qRT-PCR 检测对于循环性定型环阶段/早期配子体的量化具有敏感性和特异性，可用于增加我们对调节恶性疟原虫传播的流行病学过程的理解。