A feline kidney cell line-based plaque assay for feline calicivirus, a surrogate for Norwalk virus

Feline calicivirus (FCV) has been used by researchers as a surrogate for Norwalk virus (NV), since they share a similar genomic organization, physicochemical characteristics, and are grouped in the same family, Caliciviridae. Unlike NV, however, FCV can grow in established cell lines and produce a syncytial form of cytopathic effect. In this report, we describe the development and standardization of a plaque assay for FCV using monolayers of an established line of feline kidney (CrFK) cells in 12-well cell culture plates. The assay method has demonstrated reproducibility, ease of performance and resulted in clear plaque zones, readable in 24 h after virus inoculation. The infectivity titre of the virus by this plaque assay agreed well with tissue culture infectious dose(50) (TCID50) determinations. The described plaque assay would be a valuable tool in conducting various quantitative investigations using FCV as a model for NV and Norwalk-like viruses (NLV). Crown Copyright (C) 2002 Published by Elsevier Science B.V. All rights reserved.