POLIOVIRUS-1 ADSORPTION ONTO AND DESORPTION FROM MONTMORILLONITE IN SEAWATER - SURVIVAL OF THE ADSORBED VIRUS

It is an acknowledged fact that most viruses in the aquatic medium are present in an aggregated form or adsorbed to particulate matter and e specially clay matter. This adsorption is a parameter that must be tak en into account when dealing with the natural inactivation of viruses in an aquatic medium. The adsorption of poliovirus-1 in seawater was e xamined on Na-montmorillonite. It proved to be a quick (less than 30 m in) and mass phenomenom depending on the Na-montmorillonite concentrat ion. As a matter of fact, whereas more than 99.9% of viruses are adsor bed in less than 30 min in the presence of 500 mg.l-1 of Na-montmorill onite, the adsorption percentage under the same conditions is yet arou nd 70% with a concentration of 3 mg.l-1. A comparison between the surv ival durations of poliovirus-1, be it free or adsorbed onto Na-montmor illonite in a seawater with a salinity of 33 g.1-1 at 25-degrees-C, sh owed that the survival duration was not significantly increased in the presence of low concentrations (3 and 15 mg.1-1 of Na-montmorillonite ). Conversely, an increase in the survival duration has been demonstra ted in the presence of 500 mg.l-1 of Na-montmorillonite. Desorption te sts on adsorbed poliovirus-1 showed that the elution with a 0.1M borat e-3% beef extract buffer at pH 9 made it possible to get an elution of 76% on average.