Virucidal Efficacy of a Disinfectant for Use on Inanimate Environmental Surfaces For Norovirus

The U.S. Environmental Protection Agency (EPA) requires an infectivity assay to be conducted to determine the virucidal efficacy of disinfectants used on hard, inanimate environmental surfaces. Presently, there are no reliable in vitro infectivity assays available for Norovirus. The EPA has approved the use of surrogate viruses to be used as a model virus to determine the virucidal efficacy of these viruses on hard, non-porous environmental surfaces. View the EPA approved surrogate viruses by opening the OCSPP 810.2000 General Considerations for Uses of Antimicrobial Agents document and reference and reference section (f) (3) (ii), (iii), and (iv).

Purpose of Test

This test method is used to evaluate the efficacy of water soluble powders, liquids, or spray disinfectants for hard, non-porous surfaces against feline calicivirus as a surrogate for human Norovirus for registration with regulatory agencies such as the U.S. EPA and Health Canada. This method is intended to simulate and evaluate products intended for mop, soak, or spray based applications. Norovirus, a member of the Caliciviridae family, is a non-enveloped RNA-containing virus and is an important cause of gastroenteritis in humans. Little is known about disinfectant efficacy against this virus due to the inability to propagate the virus in-vitro. Feline Calicivirus, also a member of the Caliciviridae family, serves as a valuable model virus for efficacy testing of Norovirus since these viruses share many similar characteristics and Feline Calicivirus can be propagated in cell cultures.

Summary of Test

Duplicate glass Petri dishes (“carrier”) are inoculated with the test virus and the virus is dried onto the carrier. The carriers are individually inoculated with an aliquot of the use dilution of the test substance (liquid products), or to the amount of spray released under use conditions (spray products). The inoculated carriers are held for the requested exposure time at the requested exposure temperature. Following exposure, the contents of the carriers are neutralized and serial dilutions of the neutralized test substance are performed. The dilutions are then assayed for viral infectivity by an assay method specific for the test virus. Appropriate virus, test substance cytotoxicity, and neutralization controls are run concurrently. Typically, most regulatory agencies require complete inactivation of the virus in all dilutions assayed.