Development of a new cell culture-based method and optimized protocol for the detection of enteric viruses

The development of rapid and effective methods to detect water- and food-borne enteric viruses is important for the prevention and control of mass infection. This study represents an attempt to develop a reliable cell culture-based detection system and optimize an effective and rapid protocol for the assaying of environmental samples for the presence of infectious enteric viruses. Six enteric viruses were used in this study: poliovirus, Coxsackie virus A9, Coxsackie virus B5, human rotavirus G1, hepatitis A virus, and adenovirus type 41. Among the cell lines from humans (A549, HeLa, HEK293, and HFF) and other primates (Vero, BS-C-1, FRhK-4, BGMK, and MA104), a cytopathic effect (CPE) analysis indicated that the MA104 cell line was the most optimal for use in the detection of infectious enteric viruses. Both the sensitivity and specificity of virus detection in MA104 cells were similar to or higher than those in standard BGMK cells. Next, a method was developed for the determination of the infectiousness of enteric viruses using the colorimetric thiazolyl blue (MTT) assay. This assay utilizes 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide to yield % values based on colorimetric results. These results were compared with those from a conventional CPE-based TCID(50) assay, revealing no statistically significant difference between the two methods. The MTT% values in MA104 cells were comparable to those in BGMK cells. This MA104 cell-based MTT assay could substitute for the classical BGMK cell-based CPE assay for infectious enteric viruses.