IFIT1 Negatively Regulates Type Ⅰ Interferon Against HSV-1 Or PRV Virus Infection

Herpes simple virus-1(HSV-1)virus was recognized as one of the common pathogens threatening human health,whichinfected damaged skin cells or mucous membrane cells,resulting in various human diseases Pseudorabies virus(PRV)belong to varicella virus subfamily.Both HSV-1 and PRV viruses are double-stranded DNA viruses.Increaseing studies have shown that HSV-1 and PRV viruses invade cells and activate cytosolic DNA sensor c GAS which synthesizes cyclic GMP-AMP(c GAMP)from AMP and GMP upon activation.c GAMP acts as a second messenger,which in turn activates the adapter protein STING and subsequently recruits TBK1 to phosphorylate the IRF3.The activated IRF3 translocated into the nucleus and induce the type I IFN expression initiating antiviral responses by interferon stimulated genes(ISGs).Recently,the role of interferon-induced protein with tetratricopeptide repeats(IFITs)family in the viral infection process has attracted the attention.It has been found that IFIT3 positively regulate RIG-I signaling pathway by recruiting STING and TBK1 and enhances the activation of IRF3 and NF-κB pathway,which promote the expression of type I interferon and activate antiviral immune responses to inhibit the proliferation of viruses.However,the antiviral function and mechanism of other IFIT family proteins remain unclear.In this study,IFIT1 knock out L929 cell line was created by CRISPR/Cas9 technology,and the expression of IFIT1 protein in the knock out cell line was evaluated by Western blotting.Compare to WT cells,the m RNA levels of type I interferon and downstream ISGs increased significantly in IFIT1 knock out cells.However,IFIT1 deficiency had no significant effect on the production of IFN and CXCL10 induced by Poly(I:C).These results suggest that IFIT1 negatively regulate the DNA sensing signaling pathway.To further study the role of IFIT1 in antiviral response,a CRISPR/ Cas9technology-modified HSV-1-VP26-m Cherry virus was used to infected with the IFIT1 knockout cells.And the viral load was determined by measuring the fluorescence signal and the virus copy number.Our results showed that the production of IFN and ISGs was significantly increased in IFIT1 knockout cells upon virus infection.And upon HSV-1infection,the survival rate of IFIT1 knockout cell line was 49% higher than that of WT cell line.The virus replication ability in IFIT1 knockout cells was markedly reduced,suggesting the deletion of IFIT1 gene was beneficial to resist HSV-1 infection.Consistently,the expression of IFN and ISGs induced by PRV was significantly increased in IFIT1 knockout cells.Cell proliferation experiments showed that the survival rate of IFIT1 knockout cell line was higher than the WT cell line after PRV infection.In conclusion,IFIT1 ko negatively regulate the production of IFN-β induced by DNA virus HSV-1 and PRV,and deletion of IFIT1 protects cells from virus invasion.Our studies provide a new strategy for developing therapeutic drug for HSV-1 and PRV infection related diseases treatment.