Evaluation of animal origin cell cultures for in vitro cultivation of noroviruses

Noroviruses are a leading cause of acute non-bacterial gastroenteritis throughout the world. So far, in vitro growth of these viruses has not been achieved in human origin cell lines and limited efforts have been made to evaluate the susceptibility of animal origin cell cultures. The main objective of this study was to evaluate primary and established cell cultures from a variety of animal species for in vitro growth of human noroviruses. A total of 19 cell cultures from 11 different animal species were evaluated. Cell monolayers were inoculated with one of the two fecal samples known to contain noroviruses. The infected cell monolayers were observed daily for up to 5 days for any cytopathological effects (CPE) after which the infected cell suspension was inoculated in their respective fresh cells for a total of five blind passages. At fifth blind passage RT-PCR assay was used to detect the presence of norovirus RNA. None of the blind passage in any cell culture showed the evidence of any morphological change. When tested by RT-PCR, fifth cell culture passages from all cells were negative for norovirus RNA. These results indicate that the 19 cell types used in this study are not susceptible to noroviruses and that search should continue for a suitable cell culture system in which noroviruses can be isolated, propagated, and titrated.