| Feline herpesvirus 1(FHV-1),is a member of the Varicellovirus genus,Alphaherpesvirus subfamily and mainly cause feline viral rhinotracheitis.It has only one serotype and shows a narrow infection spectrum,mainly infects feline animals(including tigers and leopard).Clinically,FHV-1 mainly causes the symptoms of high fever,inappetence,salivation and ocular and nasal discharge,and can also lead to conjunctivitis and even blindness.Like many other herpesviruses,latent infection is a typical feature of FHV-1 infections,which is also an important potential infection source.In response to viral infection,host cells activate various antiviral defense mechanisms to inhibit virus replication.While Feline herpesvirus 1(FHV-1)manipulate the early innate immune response in the host in many different ways,host could activate antiviral response again to counteract it through unknown mechanisms.microRNAs(miRNAs),serving as a class of regulatory factors in host,participate in regulation of host innate immune response against virus infection.To explore the vital role of miRNAs involved in FHV-1 infection,miRNA libraries from the CRFK cell line before and after infection with FHV-1 were sequenced using Illumina high-throughput sequencing.Through bioinformatics analysis,we found 11 stem-loop structures of vmiRNA precursor derived from FHV-1 genome for the first time,encoding a total of 19 mature vmiRNAs,which were distributed in clusters mainly in the genome of FHV-1,similar to other ?-herpesviruses.Five of these vmiRNAs were located in LLT(Large Latency-associated Transcripts)regions,and seven vmiRNAs had two copies in IRS and TRS regions of the genome,which were encoded by positive and negative strand,respectively.Target genes of viral miRNAs were subjected to prediction and GO analysis in both the host and virus.And the results revealed that these viral miRNAs were involved in metabolic processes,biological regulation,viral reproduction,the immune response and other complex cellular processes,which formed an extensive regulatory network with target genes.380 and 376 known host miRNAs were identified,along with 55 and 50 novel host miRNAs predicted using miRDeep2 software,in libraries from FHV-1 infected and uninfected cells,respectively.Moreover,a total of 33 host miRNAs showed significantly differential expression after infection with FHV-1,including 11 upregulated and 22 downregulated miRNAs.Among these miRNAs,we randomly selected 16 miRNAs to verify the results via stem-loop RT-PCR,which were in agreement with the results obtained from deep sequencing.We selected the miR-26 a and miR-101 for further study according to the results of high-throughput sequencing.In this study,we found that FHV-1 infection upregulated the expression level of miR-26 a and miR-101 after FHV-1 infection and both of which could promote type I IFN signaling by targeting Suppressors of Cytokine Signaling 5(SOCS5),thus inhibiting viral replication.Furthermore,since SOCS5 is a common target of miR-26 a and miR-101,the expression level of SOCS5 is significantly downregulated after FHV-1 infection.Serving as a negative regulator of JAK-STAT pathway,SOCS5 knockdown enhances the effect on type I IFN-mediated antiviral response,while overexpression of SOCS5 promoted FHV-1 replication due to the inhibition of IFN-I-induced signaling cascades.In this study,we analyzed the changes of miRNA expression profile before and after FHV-1 infection via high throughput sequencing.As a result,19 novel FHV-1 encoded mature vmiRNAs and some differentially expressed feline miRNAs was found for the first time,in which miR-26 a and miR-101 could significantly inhibit FHV-1 replication.Moreover,the specific molecular mechanism was studied in detail.Our study fills in the gaps in the miRNA research of FHV-1 and shed new light on the important roles of miRNAs in FHV-1 infection,and meanwhile demonstrated a new strategy of host miRNAs defense against FHV-1 infection by enhancing the IFN-I antiviral signaling. |
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