Concentration of enteric viruses in large volumes of water using a cartridge-type mixed cellulose ester membrane.

A viral adsorption-elution method using a flat/disk-type electronegative membrane (diameter of 47-90 mm) has been widely utilized to concentrate viruses in relatively small volumes of water (up to 10 L) due to limited filtration area. In the present study, we aimed to develop a virus concentration method that is based on the same principle and yet allows concentration of large volumes of water using a cartridge-type electronegative membrane. We modified two electronegative membrane-based methods for this purpose (i.e., Mg(2+) method and Al(3+) method) and determined recovery efficiencies of poliovirus and murine norovirus inoculated in water samples. The virus recovery efficiency of the Al(3+) method substantially decreased as the volume of water sample increased. In contrast, Mg(2+) method showed stable virus recovery efficiencies (10-54 %) even when 40 to 1,000 L of river and tap water samples were processed. The volume of the concentrate (400 mL) can be further reduced to 1.5 mL by a Centricon plus-70 centrifugal ultrafiltration device with overall recovery efficiencies of 8.8-16 %. Our results demonstrated that the newly developed virus concentration method enables detection of as low as 10(1) copies/L of viruses in water samples.