Transcriptome Analysis Of Acutely And Persistently Foot-and-mouth Disease Virus Infected BHK-21

Foot-and-mouth disease virus(FMDV)is a single positive-stranded small RNA virus and a causative agent of foot-and-mouth disease(FMD)infection in cloven-hoofed animals.It is featured as high infectivity,rapid spreading and rich diversity in spreading routes etc.Animals acutely infected with FMDV will show symptoms such as fever and skin ulceration.The failure of viral clearance during acute infection stage may induce persistent infection,which will result in huge financial lose to the local animal husbandry.Currently,studies on host cells acutely and persistently infected with FMDV are far from enough.Further study is of vital significance to the understanding of the infection process of FMDV and may provide new approach to prevention and treatment of FMD in the future.In this study,RNA-Seq technology was used to analyze the transcriptome of BHK-21 cells acutely and persistently infected with FMDV.It was found that 1162 genes of host cell are differentially expressed in FMDV acute infection.These differentially expressed genes(DEGs)were significantly enriched in cellular components,cellular metabolism,cell cycle,tRNA aminoacylation,MAPK signaling pathway,TNF signaling pathway,TGF-? signaling pathway,ribosomal and other cellular functions and cell signaling pathways.In addition,1195 alternative splicing(AS)events were identified following FMDV infection.The differences in gene expression and AS events indicate a change in many host cell responses following viral infection.Subsequently,we analyzed and compared the transcriptomes of acutely infected and persistently infected BHK-21 cells.It is found that the gene expression levels of these two cells were significantly different.A total of 8378 DEGs significantly enriched in biological processes such as cell metabolism,biosynthesis,and endocytosis were identified.In-depth analysis of these DEGs reveals that many ribosomal and translation-related genes were significantly down-regulated in persistently infected cells.Meanwhile,more immune-related genes were activated in persistently infected cells.In addition,157 DEGs are differentially expressed in both cells with different variation trends.These genes may be the origin of the different characters between the two cells.Since DEGs are significantly enriched in the MAPK signaling pathway in both the acutely infected and persistently infected BHK-21,we focus on the role of this pathway in FMDV infection.It is found that MAPK/ERK and MAPK/p38 signaling pathways are activated in cells with FMDV infection.Inhibiting them can significantly inhibit FMDV infection.It is worth noting that the expression levels of MAPK14 and Hspb1 genes in MAPK signaling pathway are significantly lower in persistently infected cells than that in acutely infected and mock infected cells.Knowckdown of these two genes with shRNA can significantly reduce the mRNA and protein expression level of FMDV non-structural protein 3D.The mRNA and protein levels of protein 3D decreased significantly,magnifesting the important roles MAPK14 and Hspb1 play in FMDV infection.It is likely that persistently infected cell lines may inhibit FMDV replication via down-regulating the expression of these two genes.This study provides an in-depth analysis of the transcriptomes of acutely infected and persistently infected cells,revealing the variation in gene expression between them and validating the important role of the MAPK signaling pathway.Further,this study may provide a novel route to the research on molecular mechanisms of persistent infection and provide substantial data for searching for the key host factor in the fightting against FMDV.