Rotavirus concentration from raw water using positively charged filters.

Positively charged (PC) Zeta Plus (30 S) filters and talc-Celite (TC) layers were tested for their ability to concentrate human rotavirus (strain Wa) from seeded samples of raw water (RW), collected from the Ottawa River. In the TC technique, the RW sample was preconditioned by adding Earle's balanced salt solution (1:100) and reducing the pH to 6.0 before passing it through the TC layer. Almost 6% of the input virus was lost in the filtrate. Using 1 X tryptose phosphate broth (TPB) at pH 9.0 as an eluent, 48% of the virus could be recovered from the layers. With the 30 S PC filters, no sample preconditioning was required and no virus was detected in the filtrates. In virus elution from these filters, 1 X TPB (pH 9.0), and a mixture of 6% glycine + 6% arginine (pH 9.0) gave virus recoveries of 44% and 46%, respectively. When these same two eluents were used in sequence to recover the rotavirus from 30 S PC filters, a virus recovery of about 70% was obtained. However, when 20 1 vols. of seeded raw water were concentrated using 30 S PC filters (142 mm diameter), and polyethylene glycol hydroextraction was used for second-step concentration of the eluates, only 16% of the input infectious virus could be recovered. The 30 S PC filters were then used to recover naturally occurring rotaviruses from the waters of the Ottawa River. After concentration, these viruses were detected and quantitated in MA-104 cells using an indirect immunoperoxidase staining technique.