Development of a method for concentration of rotavirus and its application to recovery of rotaviruses from estuarine waters.

As part of our studies on the ecology of human enteric viruses, an improved method for detection of rotaviruses in water was developed, and their presence in Galveston Bay was monitored. Samples (378 liters) of estuarine water adjusted to pH 3.5 and a final AlCl3 molarity of 0.001 were filtered through 25-cm pleated cartridge-type filters (Filterite Corp., Timonium, Md.) of 3.0- and 0.45-micron porosity. Adsorbed virus was eluted with 1 liter of 10% tryptose phosphate broth, pH 9.5. Primary eluates were reconcentrated to a final volume of 10 to 20 ml by a simple and rapid magnetic iron oxide adsorption and elution procedure. Two percent casein at pH 8.5 effectively eluted rotavirus from iron oxide. A total of 21 of 72 samples of water, suspended solids, fluffy sediments, and compact sediments collected in different seasons in Galveston Bay yielded rotaviruses. Recovery of rotaviruses varied from 119 to 1,000 PFU/378 liters of water, 1,200 PFU/1,000 g of compact sediment, 800 to 3,800 PFU/378 liters of fluffy sediment, and 1,800 to 4,980 PFU from suspended solids derived from 378 liters of water based on immunofluorescent foci counts on cover slip cultures of fetal monkey kidney cells.