Ozone disinfection dynamics of enteric viruses provide evidence that infectious titer reduction is triggered by alterations to viral colloidal properties.

The inactivation dynamics of three enteric virus species (polio-, rota- and parvovirus) were analysed in different aqueous suspensions by using O3 under continuous flow conditions. A mathematical model for the reaction rate of infectious titer reduction was proposed, based on the thermodynamic principles of phase behaviour of colloids suspended in aqueous environments. Up to a certain threshold dosage of residual ozone (RO), and depending on the type of test virus and the ionic or organic load in the stock suspension, the logarithm of the reaction rate constant of viral inactivation rate was observed to vary in a rather sigmoidal manner with log RO concentration. Data from photon correlation spectroscopy, electron microscopy and tensiometric analysis suggested that below the threshold RO, the pattern of virus inactivation dynamics reflects the varying potential of different-sized viral particles (VPs) to adsorb to the cellular monolayer. There is strong evidence that oxidant-induced surface activity of organic matter causes redistribution of VP infectivity. This hypothesis was statistically corroborated inasmuch as experimental inactivation data proved to be satisfactorily fitted by a logistic equation. It was concluded that viral infection, and thus viral inactivation, is a complex process which is governed largely by the classical laws of colloidal behaviour. The latter is suggested to appreciably determine the capability of inoculated VPs to infect host cultures. This notion may especially be cause for concern when regulatory requirements for virus disinfection are being based on titration results from in vitro testing procedures.