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Abstract@#Introduction: Atherosclerosis is a chronic inflammatory disease initiated by the accumulation of macrophage derived foam cells in the intima layer of artery. In mice model of atherosclerosis, murine norovirus-4 has been shown to accelerate atherogenesis. In cells, lipid biometabolism is regulated by peroxisome proliferator activated receptor γ (PPARγ). Since PPARγ is predominantly expressed in macrophages and mice macrophages are MNV-1 proliferation-permissive host, we hypothesised that PPARγ ligands may regulate atherogenesis. Methods: MNV-1 was generated via RNA-based recovery system and used to infect the RAW 264.7 cells, then subjected to oxidized low-density lipoprotein (oxLDL)-loaded and treated with ciglitazone or 15-deoxy-Delta(12,14)-PGJ(2)(15d-PGJ2). Foam cell formation was evaluated and the MNV-1 infection in all treatments was confirmed using virus titration (50% tissue culture infective dose; TCID50) and polymerase chain reaction (PCR). Results: Increment of lipid droplets was observed in all oxLDL treatment involving MNV-1 infection, ciglitazone or 15d-PGJ2 in the cytosol of RAW 264.7 cells over time compared to non-oxLDL treated cells. From the cholesterol ester (CE) content analysis amongst the oxLDL-loaded cells however, we found MNV-1 did not elicit increment of CE content. Treatment with 15d-PGJ2 resulted in increase of the CE content in oxLDL-treated cells. Interestingly, MNV-1 and ciglitazone had synergistic effect in reducing the CE content in oxLDL-treated cells. Conclusion: oxLDL stimulates foam cells formation in RAW 264.7 cells. However, MNV-1 infection did not contribute to RAW 264.7 cells derived-foam cells formation. On the other hand, 15d-PGJ2 promotes foam cells formation whilst ciglitazone inhibits the formation of foam cells derived from MNV-1-infected macrophages.
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Objective To analyze the effect of transport and storage conditions on the detection of pathogenic nucleic acid MHV, Reo-3, MNV in laboratory mouse cecal contents samples. Methods MHV, Reo-3 and MNV were mixed with mouse cecal contents and used as reference samples,respectively. They were placed in the lysis buffer of RNA extraction reagent(buffer AVL)or normal saline, and stored at 4℃ and room temperature(22℃-25℃). RNA of these samples was extracted at 1,2,3,7,and 14 days. Then the amount of nucleic acid in samples was detected by real-time fluorescence quantitative PCR. Results A greater decrease of the amount of nucleic acid was observed when the samples were placed in normal saline than that kept in buffer AVL. The amount of nucleic acid in samples stored at 4℃ was found to be higher than that stored at 25℃ room temperature. The amount of nucleic acid in the samples which were kept in buffer AVL at 4℃ for 3 days was higher than 50%,still detectable in the samples kept for 7 days,and undetectable at 14 days. Conclusions Mouse cecal content samples are preferably stored in the lysis buffer of RNA extraction reagent and transported at 4℃ for the detection of MHV, Reo-3, and MNV nucleic acid. It is better to complete the detection test within 3 days.
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0bjective To identify the molecular structure and genome homology characteristics of a GV murine norovirus (MNV) from wild mice.Methods@#Nucleic acids were extracted from collected mouse intestinal specimens and subjected to high-throughput sequencing. The whole genome sequence was obtained by RT-PCR and RACE method .@*Results@#The MNV genome was 7, 832 bp in length, with 76.8%-78.1% nucleotide identity to other selected murine norovirus strains in GenBank. The P2 region, the hypervariable area in viral protein 1 gene shows highest heterology, and the identity was among 60.9%-78.1%, lower than other genes regions. The result demonstrated the higher variability of this newly isolated WNV strain.@*Conclusions@#The wild-type MNV isolated in this study is first reported in China, which enriched the domestic MNV gene pool and provided a reference for understanding the molecular genetic characteristics and evolutionary origin of MNV in China.
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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 .