Evaluation of a method to re-use electropositive cartridge filters for concentrating viruses from tap and river water

Electropositively charged filters are frequently used for concentrating enteric viruses from large volumes of water. A major disadvantage to the use of these filters, however, is that they are not cost-effective. At US$ 150–180 per filter, routine viral monitoring of water is cost-prohibitive. This study describes the development of a method which allows a filter to be used up to three times, achieving comparable recoveries to new filters. Zetapor 1MDS and N66 Posidyne electropositive filters were tested. The method was analyzed using tap water and Ohio River water that was spiked with poliovirus. Tap water recoveries averaged 32% for new filters, 30% for filters used twice, and 38% for filters used three times. River water recoveries averaged 68% for new filters, 83% for filters used twice, and 100% for filters used three times. RT-PCR and dot-blot hybridization were performed on sample concentrates to ensure that all viral nucleic acid from the previous test had been removed from the filters by the treatment process.