Purpose: The aim of this study was to compare the protective effects of different soil loads on a norovirus surrogate that can be cultured in vitro under three different inactivation conditions.
Methods: Artificial feces, real fecal matter, ASTM tripartite soil load and fetal bovine serum were tested as soil load for murine norovirus (MNV) in three inactivation conditions: chemical disinfection in suspension, chemical disinfection on surfaces, and heat treatment. The viruses were recovered after each treatment and detected by plaque assay.
Results: Soil load had no significant impact on inactivation of MNV in suspension by peroxyacetic acid. The ASTM medium and real fecal matter did not offer any protection to virions dried onto stainless steel against the antiviral effect of sodium hypochlorite solution. However, two types of Feclone™ and real fecal matter (10% and 20%) limited the loss of infectivity to 1 log cycle following heat treatment at 63°C for 2 min. Feclone BFPS-4 showed the most similarities to real fecal matter and thus appeared to be the best soil load. The consistency of the fecal matter seems to have an impact on the efficacy of an inactivation treatment.
Significance: These results will be helpful for studies in which a soil load is used to approximate actual conditions of human norovirus transmission and inactivation.