Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Sci Total Environ. 2014 Jan 15;468-469:757-63. doi: 10.1016/j.scitotenv.2013.08.093. Epub 2013 Sep 23.
Rainfall events can introduce large amount of microbial contaminants including human enteric viruses into surface water by intermittent discharges from combined sewer overflows (CSOs). The present study aimed to investigate the effect of rainfall events on viral loads in surface waters impacted by CSO and the reliability of molecular methods for detection of enteric viruses. The reliability of virus detection in the samples was assessed by using process controls for virus concentration, nucleic acid extraction and reverse transcription (RT)-quantitative PCR (qPCR) steps, which allowed accurate estimation of virus detection efficiencies. Recovery efficiencies of poliovirus in river water samples collected during rainfall events (<10%) were lower than those during dry weather conditions (>10%). The log10-transformed virus concentration efficiency was negatively correlated with suspended solid concentration (r(2)=0.86) that increased significantly during rainfall events. Efficiencies of DNA extraction and qPCR steps determined with adenovirus type 5 and a primer sharing control, respectively, were lower in dry weather. However, no clear relationship was observed between organic water quality parameters and efficiencies of these two steps. Observed concentrations of indigenous enteric adenoviruses, GII-noroviruses, enteroviruses, and Aichi viruses increased during rainfall events even though the virus concentration efficiency was presumed to be lower than in dry weather. The present study highlights the importance of using appropriate process controls to evaluate accurately the concentration of water borne enteric viruses in natural waters impacted by wastewater discharge, stormwater, and CSOs.
降雨事件会通过合流污水溢流（CSO）间歇性排放，将大量包括人类肠道病毒在内的微生物污染物带入地表水。本研究旨在调查降雨事件对受 CSO 影响的地表水中病毒负荷的影响，以及分子方法检测肠道病毒的可靠性。通过使用病毒浓缩、核酸提取和反转录（RT）-定量 PCR（qPCR）步骤的过程控制来评估样品中病毒检测的可靠性，这允许准确估计病毒检测效率。在降雨事件期间收集的河流水样中，脊髓灰质炎病毒的回收率（<10%）低于干燥天气条件下的回收率（>10%）。对数转换后的病毒浓度效率与悬浮固体浓度呈负相关（r(2)=0.86），而悬浮固体浓度在降雨事件中显著增加。分别使用腺病毒 5 型和共享引物的控制来确定 DNA 提取和 qPCR 步骤的效率，在干燥天气下较低。然而，这两个步骤的效率与有机水质参数之间没有明显的关系。尽管假定在干燥天气下病毒浓度效率低于降雨事件，但观察到的土著肠道腺病毒、GII-诺如病毒、肠道病毒和 Aichi 病毒的浓度在降雨事件中增加。本研究强调了使用适当的过程控制来准确评估受废水排放、雨水和 CSO 影响的天然水中水传播肠道病毒浓度的重要性。
