Methodology for recovery of indigenous viruses from primary sludge

Freon extraction method for recovery of viruses from primary sludge has been studied with sonication and the beef extract eluation methods. Several variables within the freon extraction method were worked out and it was observed that equal volume of 10% buffered beef extract (pH 7.0), as that of the sludge sample, was required for optimum virus elution. Eluate decontamination with antibiotics, dilution and plaquing over BGM cell cultures using the overlay medium without phenol red, fortified with 1.7% milk powder resulted in best recoveries without any cytotoxicity to the cell cultures. A sample volume of 20 ml primary sludge was sufficient for quantification of viruses.