Stone Will, Grabias Bryan, Lanke Kjerstin, Zheng Hong, Locke Emily, Diallo Diadier, Birkett Ashley, Morin Merribeth, Bousema Teun, Kumar Sanjai
Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases, Office of Blood Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Rockville, MD, USA.
Malar J. 2015 Nov 14;14:451. doi: 10.1186/s12936-015-0954-2.
The infectivity of Plasmodium gametocytes is typically determined by microscopically examining the midguts of mosquitoes that have taken a blood meal containing potentially infectious parasites. Such assessments are required for the development and evaluation of transmission-reducing interventions (TRI), but are limited by subjectivity, technical complexity and throughput. The detection of circumsporozoite protein (CSP) by enzyme-linked immunosorbent assay (ELISA) and enhanced chemiluminescent slot-blot (ECL-SB) may be used as objective, scalable alternatives to microscopy for the determination of infection prevalence.
To compare the performance of the CSP ELISA and ECL-SB for the detection of mosquito infection, four groups of Anopheles stephensi mosquitoes were infected with cultured Plasmodium falciparum gametocytes. At day-8 post-infection (PI), parasite status was determined by microscopy for a sample of mosquitoes from each group. At days 8 and 10 PI, the parasite status of separate mosquito samples was analysed by both CSP ELISA and ECL-SB.
When mosquito samples were analysed 8 days PI, the ECL-SB determined similar infection prevalence to microscopy; CSP ELISA lacked the sensitivity to detect CSP in all infected mosquitoes at this early time point. When mosquitoes were analysed 48 h later (10 days PI) both assays performed as well as microscopy for infection detection.
Whilst microscopical examination of mosquito guts is of great value when quantification of parasite burden is required, ECL-SB and CSP ELISA are suitable alternatives at day 10 PI when infection prevalence is the desired endpoint, although CSP ELISA is not suitable at day 8 PI. These results are important to groups considering large-scale implementation of TRI.
疟原虫配子体的传染性通常通过显微镜检查吸食了含有潜在感染性寄生虫血液的蚊子的中肠来确定。这种评估对于减少传播干预措施（TRI）的开发和评估是必需的，但受到主观性、技术复杂性和通量的限制。通过酶联免疫吸附测定（ELISA）和增强化学发光斑点印迹法（ECL-SB）检测环子孢子蛋白（CSP），可作为确定感染率的客观、可扩展的显微镜替代方法。
为比较CSP ELISA和ECL-SB检测蚊子感染的性能，将四组斯氏按蚊用培养的恶性疟原虫配子体感染。感染后第8天（PI），通过显微镜检查每组的一部分蚊子样本以确定寄生虫状态。在感染后第8天和第10天，通过CSP ELISA和ECL-SB分析单独的蚊子样本的寄生虫状态。
在感染后第8天分析蚊子样本时，ECL-SB确定的感染率与显微镜检查相似；CSP ELISA在这个早期时间点缺乏检测所有感染蚊子中CSP的敏感性。在48小时后（感染后第10天）分析蚊子时，两种检测方法在检测感染方面与显微镜检查表现相当。
虽然在需要定量寄生虫负荷时，显微镜检查蚊子肠道具有很大价值，但当期望的终点是感染率时，在感染后第10天，ECL-SB和CSP ELISA是合适的替代方法，尽管CSP ELISA在感染后第8天不合适。这些结果对于考虑大规模实施TRI的团体很重要。
