Objective To investigate the natural infection rate of murine norovirus(MNV)in laboratory mice in Guangdong province.Methods\206 Mice were selected randomly from seven mice breeding facilities in this province for a survey of MNV infection rate.Reverse transcription-polymerase chain reaction(RT-PCR) was used to detect MNV in the mouse cecal contents.Results 206 samples were tested and 77 samples were positive for MNV,the infection rate was 37.38%.The mice of three facilities were infected with MNV.There wer...