Human Adenoviruses As Indicators Of Faecal Contamination And Pathogen Indices In The Environment And Shellfish

Abstract

The main aim of this study was to assess the use of human adenoviruses (HAdVs) as occurrence indicators of human enteric viruses in the environment and shellfish. The second aim was to consider human polyomaviruses (HPyVs) for the same roles. To gain a better understanding of the ecology of HAdV, their diversity in the environment was also investigated. Method development included validation of an ultrafilter for virus concentration from water samples; real-time quantitative PCR (qPCR) assay development; evaluation of culture-qPCR using different cell lines; and assessment of guanidine hydrochloride to inhibit enterovirus growth in virus quantification assays. The presence, quantity, and where possible, infectivity (using HEK-293 cells in a culture-qPCR assay with guanidine hydrochloride) of HAdVs were determined in a range of environmental samples and shellfish. The presence and quantity of HPyVs, noroviruses and enteroviruses were also determined where appropriate. HAdVs, predominantly species F and other HAdV species at lower concentrations, were frequently present in high concentrations in wastewater influent, independently of wastewater treatment plant size. They were also present in non-disinfected effluent irrespective of treatment type. HPyVs were prevalent at concentrations at least as high as HAdVs in wastewaters. In biosolids, the occurrence of HAdVs and HPyVs were comparable to enteroviruses and like wastewater, were detected more frequently than noroviruses. In urban streams, rivers and estuaries, neither HAdVs nor HPyVs were dominant in terms of their occurrence and so should be used as part of a multi-tool source tracking system. Shellfish studies showed a low occurrence of HAdVs and HPyVs, probably due to poor virus recovery. Further studies are required to investigate this. The results of this study strongly supported the hypothesis that HAdVs and HPyVs are suitable indices for viral contamination from faecal sources. Furthermore, due to their continued occurrence in the environment and their host specificity, these viruses also have potential for microbial source tracking applications. However, one caveat identified was the difficulty in recovering HAdVs, and presumably HPyVs, from shellfish. In conclusion, although it is unlikely that the detection of a single indicator by one method will be sufficient to identify health risks and faecal contamination sources, HAdVs and HPyVs together are a good option for viral indicators of faecal contamination and as pathogen indices in the environment.