Analysis Of The Genome Transcription And Protein Expression Of Pieris Rapae Granulosis Virus (PrGV)

Pieris rapae granulovirus(PrGV)infects and kills larvae of P.rapae.PrGV has been widely used for biological control of P.rapae and has become a commercially important biological insecticide.In this study,the complete genome of PrGV was sequenced and a total of 120 viral proteins were predicted as well as the gene expression pattern and protein location of PrGV were analyzed.By genomic,transcriptomic,and proteomic approaches,the interaction between this virus and its host insect was unveiled.The main results were as follow:1)The genome of PrGV had 108,592 bp in size,containing 120 ORFs.There were 62 ORFs showed high homology with genes in other GVs,which might be the core genes in GV.Five ORFs showed low homology with other GVs,which might be the PrGV unique genes.The phylogenetic analysis showed that the PrGV was closely related with ErelGV,while the HearGV was a bit distant to PrGV2)Using Illumina sequencing technology,we generated three transcriptomes of uninfected P.rapae,PrGV-infected P.rapae at 6 h p.i.,PrGV-infected P.rapae at 72 h p.i.,respectively.A total of 103 genes were found in PrGV-infected samples.Through comprehensive comparison of gene expression pattern in three transcriptomes,1224 genes(uninfected vs infected at 6 h),1638 genes(uninfected vs infected at 72 h),and 1959 genes(infected at 6 h vs infected at 72 h)were identified to be differentially expressed genes(DEG).The enrichment analysis were performed and the DEGs were classified according to the expression pattern,which showed that the genes participated in cuticle proteins,ribosomal proteins,heat shock proteins(HSPs),proteasome,oxidation-reduction reactions,apoptosis were significantly altered after PrGV infection.Our result established a link between baculovirus and host insect,and would be useful in future research.3)The component of PrGV-ODV were identified using Liquid Chromatography Mass Spectrometry/Mass Spectrometry(LC-MS/MS)technology.Except for 47 ODV genes identified in our previous study,we found two new genes(PrGV_gp003 and PrGV_gp076)were the component of PrGV-ODV.In addition,there were 33 host-derived proteins were also identified in ODV4)Gene expression patterns of PrGV in guts and whole body in infected P.rapae were determined using RT-qPCR.The PrGV_gp035,PrGV_gp046,PrGV_gp097,and PrGV_gp0114 were the early expressed gene in PrGV,which might play roles in viral early infection.While the PrGV_gp002,PrGV_gp004,PrGV_gp020,PrGV_gp021,and PrGV_gp022 were the late expressed genes,which might participate in ODV formation and facilitated viral assembling and spread.5)The PrGV proteins were fuse-expressed using E.coli expressed system,and the antibodies of viral protein were obtained.Through western blotting and immunogold labeling,the PrGV_gp002,PrGV_gp020,PrGV_gp029,PrGV_gp076,PrGV_gp086,PrGV_gp0215 PrGV_gp035,PrGV_gp042,PrGV_gp097,PrGV_gp114,PrGV_gp046,PrGV_gp054 were successfully identified in occluded body(OB)of PrGV,indicating that these proteins were the components of OB.Among them,the PrGV_gp002 was not only the component of OB,but also the component of ODV.