Doctor of Philosophy (Ph.D.)
Virginia Institute of Marine Science
The United States Environmental Protection Agency (USEPA) has established the Total Coliform Rule as an indication of health risks associated with microbial contamination of drinking and ground water. In addition, the fecal coliform test is used as an indicator to reflect the suitability of use by consumers of class A biosolids. However, numerous studies have shown that bacterial indicators are not predictive of enteric viruses, such as human adenovirus (HAdV), which are much more resistant to treatment methods than bacteria. Enteric viral contamination of estuarine waters and locally-harvested shellfish as a result of receiving effluent from wastewater treatment plants, as well as run-off from agricultural land treated with biosolids, can have serious implications for human health. Preliminary results suggest that HAdV is present in biosolids, wastewater effluent, estuarine waters receiving effluent and shellfish harvested from these receiving waters. The density, persistence and infectivity of human adenovirus in these environmental matrices are not known. The focus of this research was to address the presence, persistence and viability of HAdV in all four matrices. Presence and density of the virus was established through the use of a nested polymerase chain reaction (PCR) and quantitative PCR (qPCR). HAdV DNA was detected in 21 of the 26 biosolid samples and 21 of the 24 effluent samples assayed. The treatment method employed in the processing of the samples appeared to have an effect on the detection and concentration of HAdV DNA. Persistence of HAdV DNA in estuarine water was addressed in an in situ study using seeded microcosms containing either sterile river water or unfiltered river water under various environmental conditions during the spring, summer and fall. Unfiltered river water collected during the summer had the greatest deleterious effect on HAdV DNA persistence. HAdV DNA was most persistent, under all environmental treatments, during the fall. An in vitro study of sterile river water confirmed that temperature, not salinity, had a greater effect on HAdV DNA degradation. Laboratory tank studies revealed that oysters are capable of filtering and retaining HAdV from contaminated water. In each of the three tank studies conducted, HAdV DNA was detected in tissue samples from oysters exposed to seeded river water for 18 hours. It was also established that the oysters could depurate the virus, in an open system, in as little as three days. Integrated cell culture (ICC) - qPCR was used to determine the viability of detected viral particles. No direct correlation between the detection of HAdV DNA and the presence of viable viruses was found. Frequently, samples that contained HAdV DNA failed to produce viable virions. Current research corroborates these results, suggesting the detection and persistence of viral DNA is not sufficient evidence to support the assumption of viability.
© The Author
Quidort, Wenda Lee, "Detection and infectivity of human adenovirus in wastewater effluent, biosolids, and shellfish, and its persistence in estuarine water" (2013). Dissertations, Theses, and Masters Projects. Paper 1539616818.