A comparison of different concentration methods for the detection of viruses present in bottled waters and those adsorbed to water bottle surfaces.

This study aimed to provide a tool for selecting the best approach to virological testing of bottled waters. Different methods were investigated. Method A examined the recovery of virus RNA following in situ lysis of virus particles in the aqueous phase and of those adhered to the bottle wall, method B examined the recovery of virus RNA following lysis of virus particles in the aqueous phase, and method C examined the recovery of intact virus particles. Method C generated the lowest genome recovery rate regardless of the water and virus type used, therefore comparison was mainly conducted between methods A and B.The effects of independent variables on the viral RNA recovery rate were determined by full factorial design. These independent variables included three waters (differing in mineral composition), four viruses (poliovirus 1, hepatitis A virus, Norovirus, and the MS2 phage), three incubation times (0, 10, and 20 days), and two methods (A and B). According to the results, each factor influenced the recovery rate of viral RNA with the exception of incubation time. Statistical analysis identified interactions between the factors. The strongest interactions involved the water and virus types, as well as the methods. The results suggested that method A should be used for the concentration and detection of hepatitis A virus, regardless of the divalent cation concentration of the bottled water. Method A was most suitable for water with the highest mineral content (divalent cation concentration of 250 mgL(-1)) and for the analysis of viruses capable of adsorbing onto the bottle walls (Poliovirus 1). Method B could be recommended for the analysis of water whose cation concentration is unknown.