Molecular characterization of murine norovirus isolates from South Korea

The recently discovered murine norovirus (MNV) is an important surrogate virus for studying the human norovirus (NoV) because of its ability to replicate in conventional cell cultures using mouse macrophage cell lines. In addition, the impact of MNV is significant due to the high prevalence of MNV in commonly used laboratory animals in biomedical research. The prevalence and molecular characteristics of MNV could differ in various regions of the world. Therefore, the objectives of this study were (1) to determine the prevalence of MNV in animal laboratories in South Korea and (2) to compare and characterize novel MNV isolates with reported MNV isolates. We investigated 115 mouse specimens, including feces and tissues collected at five major animal facilities in South Korea, using both cell cultivation and RT-PCR assays. More than 20% of the investigated samples were positive for the virus by RT-PCR. When the complete genomes of two MNV isolates were sequenced and their sequences were compared to MNVs previously identified in North America and Germany, distinct nucleic acid sequences were identified in our new isolates.