The Mechanisms of Poliovirus Inactivation by Chlorine Dioxide and Iodine and the Effects of Cations on Halogen Inactivation
Chlorine dioxide and iodine inactivated poliovirus most efficiently at pH 6.0. Sedimentation analyses of viruses inactivated by chlorine dioxide or iodine at pH 10.0 showed that viral RNA separated from the capsids converting the virions from 156S structures to 80S particles. It was shown, however, that the separation of the RNA from the capsids was not the cause of virus inactivation by chlorine, chlorine dioxide or iodine. The RNA released from both chlorine dioxide and iodine-inactivated viruses cosedimented with intact 35S viral RNA. Both chlorine dioxide and iodine reacted with the capsid proteins of poliovirus and changed the isoelectric point from pH 7.0 to pH 5.8. However, the mechanisms of inactivation of poliovirus by chlorine dioxide and iodine were found to differ. Iodine inactivated viruses by impairing their ability to adsorb to HeLa cells; whereas chlorine dioxide-inactivated viruses were able to adsorb, penetrate, and initiate uncoating normally. Sedimentation analysis of HeLa cells infected with chlorine dioxide-inactivated viruses showed a reduced incorporation of 14C uridine into new viral RNA. Therefore, chlorine dioxide inactivated poliovirus by reacting with the virus RNA and impaired the ability of the genome to act as a template for RNA synthesis.
The presence of 0.1 M KCl or 0.1 M MgCl2 enhanced the rate of inactivation of poliovirus by chlorine at both pH 6.0 and 10.0. Iodine inactivation of poliovirus was not affected by the presence of KCl or MgCl2 at either pH 6.0 or 10.0. Inactivation of poliovirus by chlorine dioxide was reduced in the presence of KCl or MgCl2 at pH 10.0 but no effect was seen at pH 6.0. Sedimentation analyses of viruses inactivated in the presence of KCl or MgCl2 indicated that the salts inhibited the separation of the RNA from the viral capsids under certain conditions. Moreover, the presence of MgCl2 was found to stabilize chlorine or chlorine dioxide-inactivated viruses in an RNA-containing structure with a sedimentation coefficient of 120 to 130S. It was concluded, then, that the rates of inactivation of poliovirus by halogen compounds, as well as the gross structural changes associated with virus inactivation, are highly dependent on the pH of the reaction and on the ionic environment.
Project Numbers: A-066-NMEX, 1423625, 1345657