RESUMEN
Objective To investigate the natural infection status of murine norovirus ( MNV) in laboratory mice in Shanghai area and isolate MNV from mouse cecal feces .Methods To collect cecal contents and serum samples from 319 specific pathogen-free ( SPF) mice coming from different research institutions .Reverse transcription-polymerase chain reaction ( RT-PCR) and enzyme linked immunosorbent assay ( ELISA) were used to detect MNV infection in the mice , re-spectively.The positive stool samples were diluted and filtered through 0.22 μm membrane, inoculated into RAW 264.7 cells, and then identified by RT-PCR.Results There were 95 positive results in the 319 cecal samples by RT-PCR, and the positive rate was 29.78%.Among 180 serum samples which were tested by RT-PCR, 70 samples were positive by ELISA, and the positive rate was 38.89%.The infected RAW 264.7 cells showed cytopathic effect ( CPE) within 72 h. After 3 times of freezing and thawing , RT-PCR obtained a 187 bp band.Conclusions The results from the present study show that there is a high natural infection rate of MNV in laboratory mice in Shanghai area , and the strict breeding manage-ment must be strengthened .