Recovery of human norovirus from water by virus concentration methods.

The aim of this study was to evaluate the applicability of virus concentration methods to detect human norovirus (HuNoV) in water. One conventional virus concentration method using an electropositive filter (1MDS-method) and two methods developed by our research group using an electronegative filter (Mg-method and Al-method) were subjected to recovery tests of the HuNoV strain GII.4, which was obtained from a diarrhea patient, and poliovirus (PV) type 1 inoculated into 5 kinds of water samples. The mean recovery yields of HuNoV by the Mg-method, determined by real-time PCR, were 186%, 80%, 167%, 15%, and 39% for MilliQ water, tap water, bottled water, river water, and pond water, respectively (n=2 each), which were generally comparable to those of PV. A similar trend was observed for the Al-method (n=8 in total), suggesting that both Mg- and Al-methods can be appropriate for concentrating HuNoVs from water samples. Unlike these two methods, no clear correlation was found between the recovery of HuNoV and PV by the 1MDS-method (n=6 in total). This study is significant because it provides observations on the use of virus concentration methods for the detection of uncultivable HuNoV in water samples.