Some Limits in Current Adsorption-Elution Methods for the Detection of Viruses in Large Volumes of Tap Water

Two types of electropositive filters (1 MDS double sheet - Cuno and AS - Seitz) were compared for Poliovirus 1, Coxsackie virus B3, Coxsackie virus A9 and E.C.H.O. virus 1 recovery from tap water with different pH levels. For small volumes of tap water sampled, both adsorbents gave equally satisfactory recoveries of Poliovirus 1 (46% to 82%) at pH 6.7, 7.9, or 9. However, elution percentages using 3% beef-extract solution pH 9.5 were generally better for 1 MDS than for AS filters. As the volume of tap water sampled increased, increasing amounts of Poliovirus were unadsorbed onto both types of filters at pH 7, 7.9, or 9. Lowering the pH to 6 gave better Poliovirus 1 and Coxsackie B3 recoveries with AS (respectively 61% and 95%) and 1 MDS filters (respectively 67% and 91%). E.C.H.O. virus 1 recovery was not affected by acidification and was lower with 1 MDS (6%) than with AS filters (37%). Coxsackie virus A9 recovery was very low for both filters (≤11%). As for electronegative adsorbents, currently available methods for concentrating viruses using electropositive filters have to be optimized to recover most enteric viruses occurring in waters.