| Norovirus outbreaks have been linked to water and food sources, warranting an investigation into the fate and transport of noroviruses in the environment. The lack of a permissive cell line means norovirus presence and survival in environmental samples has been difficult to evaluate. Their genetic diversity has made molecular detection techniques challenging as well, though recently developed broadly reactive real-time reverse transcription polymerase chain reaction (rRT-PCR) assays now allow the detection of noroviruses in a broad range of sample types. Though "real" noroviruses cannot be purified sufficiently for laboratory scale investigation into norovirus transport properties, the development of recombinant norovirus virus-like particles (VLPs) has facilitated these studies, since VLPs can be produced in very high concentrations and are readily purified.;Using new rRT-PCR assays, norovirus genomes were detected in raw and treated wastewater samples at four locations over the span of a year. Influent concentrations were high throughout the year and the three treatment technologies evaluated removed norovirus genomes to a similar extent. Of the two genogroups of noroviruses, genogroup I (GI) was released more frequently than GII, despite more steady positive influent concentrations of GII. The waste stabilization pond (WSP) system was investigated in more detail. Norovirus genomes were found to be removed in the third pond in series, and settling was found not to be a major removal mechanism, pointing instead to enzymatic or solar disinfection. In this system, noroviruses were dominantly associated with particles between 0.45 -- 180 mum in size, implying that upon release to receiving waters, they may be transported long distances since they settle very slowly due to their small size.;By employing VLPs that correspond to representative strains of GI and GII, transport properties of noroviruses were probed using dynamic light scattering (DLS) and the quartz crystal microbalance with dissipation (QCM-D). It was found that norovirus VLPs follow broadly electrostatic behavior, with attachment efficiencies increasing with ionic strength. Interestingly, pH and ion composition play very subtle roles, and impact GI and GII VLPs differently. Perhaps changes in solution chemistry cause nanoscale perturbations in the capsids, and influence deposition in dynamic ways which do not reduce to simple rules of isoelectric point and ion valence. The role of humic acid (HA) as a model for natural organic matter was investigated. The VLPs had a high affinity for HA, which adsorbed to the VLP capsids. The presence of HA was capable of causing both enhanced and decreased deposition of VLPs, depending on the relative concentrations of HA and VLPs. |
