ABSTRACT
@#Abstract：Objective To improve the replication level of varicella⁃zoster virus（VZV）in human diploid cell line MRC⁃5 and increase the yield of VZV vaccine by reducing the expression of interferon（IFN）related genes via optimizing the cell line MRC⁃5. Methods Interferon receptor 1（IFNAR1）silenced MRC⁃5 cell line（MRC⁃5IFNAR1⁃）was constructed by CRISPR／Cas9 gene editing technology，which was determined for the relative expression of IFNAR1 mRNA，and for those of mRNA of IFN related genes IFNβ and OAS1 after VZV infection by qRT⁃PCR to evaluate the effect of gene silencing. Gene mutation sequences were further identified by sequencing of the silenced sites. The replication of VZV in MRC⁃5 and MRC⁃5IFNAR1⁃ cell lines was compared 168 h after VZV infection by using qRT⁃PCR and plaque formation unit（PFU）assay， to evaluate the effect of MRC⁃5IFNAR1⁃cell line on VZV replication. Results The growth status of MRC⁃5IFNAR1⁃ cell line wasconsistent with that of MRC ⁃ 5 cells，and the relative expression of IFNAR1 mRNA decreased by 73%；The relative expressions of IFNβ and OAS1 mRNA in MRC⁃5IFNAR1⁃ cell line were 61% and 90% lower than those in MRC⁃ 5 cells respectively after VZV infection；In addition，168 h after VZV infection，the level of DNA replication and the titer of VZV increased by 5. 7 folds and 4 folds respectively. Conclusion The successful establishment of MRC⁃5IFNAR1⁃ cell line may be a potential scheme to increase the yield of vaccines based on human diploid cells，and provided a reference for expanding production of VZV vaccine.