Effects of Storage in Recovery Media on Sublethally Heated Polio and Echo Viruses

Abstract

In vitro renaturation of heat-denatured virus particles was studied using poliovirus type 1, strain CHAT and echovirus type 6, strain D'Amori. Six recovery media were chosen to simulate heat-processed foods and mildly processed or raw foods and to represent a range of compositions. Virus was suspended in four heating media and processed to various degrees of inactivation. After cooling, the stressed virus was resuspended in the recovery media and incubated at 30 C for up to 7 days. Titers were determined at intervals from 3.5 h to 7 days in African Green Monkey kidney cells. The suspending medium influenced poliovirus susceptibility to heat treatments. The acidic medium produced a higher degree of inactivation in shorter time than the nutrient and ion-rich media. Echovirus was less affected than poliovirus by medium composition. No increase in titer of either virus occurred in any of the recovery media, indicating absence of renaturation mechanisms. Instead, independent of medium composition, virus titers slowly decreased over the 7-day storage period.