Development of a New Microporous Filter Method for the Concentration of Viruses from Water

Abstract

Waterborne enteric viruses are transmitted via the fecal-oral route and have been isolated from various types of water ranging from sewage to tap water. Water matrices characterized by low levels of organic material (e.g. clean surface water and tap water) contain fewer numbers of viruses than sewage and wastewater effluents. A number of methods have been developed to concentrate, elute (recover), and re-concentrate viruses from water. The goal of this dissertation is two-fold. An extensive review of the literature is provided in Appendix A that focuses on method development in the three aforementioned areas. A review of this detail has not been conducted in over two decades, and as such will contribute to the fields of water quality and environmental virology. Second, a novel and inexpensive method for the concentration of viruses (MS2 coliphage, poliovirus 1, echovirus 1, Coxsackievirus B5, and adenovirus 2) is presented in Appendix B. The method uses a new electropositive filter (comprised of nanoalumina fibers) for the capture of viruses from 20-L volumes of dechlorinated tap water. Average filter retention efficiencies for each of the viruses was ≥ 99%. Viruses that are adsorbed to filters must then be recovered (eluted). A number of inorganic solutions were evaluated for this purpose, the most effective being a moderately alkaline (pH 9.3) glycine buffered-polyphosphate solution. Secondary reconcetration of the eluates was performed using an optimized ultrafiltration method (Centricon Plus-70, Millipore, Billerica, MA), and achieved final concentrates volumes of 3.3 ± 0.3 mL. Total method efficiencies meeting the project recovery goal of ≥ 50% were obtained for each of the tested viruses except for MS2 coliphage at high input titers (45 ± 15%) and adenovirus 2 (14 ± 4%). Appendix C provides the Standard Operating Procedures, sample calculations, and detailed data for the experiments conducted. Appendix D details the steps taken towards optimizing the secondary concentration procedure in effort to meet the 50% recovery goal.