Influence of salts and montmorillonite upon heat inactivation of poliovirus in sterile water

Using semi-purified type-1 poliovirus we show that the viral inactivation rate in sterile deionised water is not influenced by the initial virus titer, remains unaffected by the saline concentration (ionic strength) of the medium nor by the valency of the introduced cations. In the presence of purified Na-montmorillonite and in similar conditions we observe the same viral decay rates. In particular the presence of clay (at least up to 205 mg.l −1 ) does not provide viruses with any protective effect against heat, as experiments carried out at different temperatures do not reveal any difference between viral inactivation rates due to the presence of montmorillonite. Furthermore viral decay rates obtained with or without clay both plot against temperature on the same regression line, following an Arrhenius-like equation with an excellent correlation coefficient.