Genomic Analysis Of Trichoplusia Ni Ascovirus 6b(TnAV-6b) Isolated From Helicoverpa Zea

Ascoviruses is highly pathogenic and highly mortality rate,and is widely recognized as a potential bioactive pesticide.It can cause a chronic but ultimately fatal disease in the larvae of Lepidoptera and Hymenoptera with circular double-stranded DNA genomes virus.However,studies were still not deep enough to theories form about the genomics of it.In this study,the complete genome of Trichoplusia ni ascovirus 6b(TnAV-6b)was sequenced for the first time.A systematic analysis of studies was conducted to determine the characteristics of their genomes by comparing all known their genomes.In order to provide reference for its pathogenic mechanism and transmission process,it provides basic data support for its improvement by means of gene editing.(1)TnAV-6b genomic DNA was sheared for shotgun sequencing to fragment sizes of 400 to 600 bp by ultrasonication and sequenced by the Solexa genome analyzer at the Beijing Genome Institution(BGI;Shenzhen,China).A total of 6,045,713 clean paired-end reads were obtained.Genome assembly was performed using the Edena?Velvet and Abyss assembly software package.ORFs were identified through the NCBI ORF finder,GeneMarkS and Geneious program.The TnAV-6b has a circular genome of 185,664 bp with a G+C content of 35.4 %.The genome has been deposited in GenBank under the accession no.KY434117.(2)The TnAV-6b genome encodes 190 predicted open reading frames(ORFs),in which 91 are in the forward orientation and 87 in the reverse.The coding region(168,585 bp)accounts for 90.9% of the total sequences.In addition,7 baculovirus repeat ORFs(bro),4 iap,7 aro and 15 TnAV-6b unique ORFs were found in the genome.Thirty-eight genes encoding enzymes involved in gene transcription,DNA replication,and nucleotide metabolism were found in the TnAV-6b genome.(3)By Relative Synonymous Codon Usage and Dinucleotide Relative Abundance analysis to reveal characterization of codon usage of Ascoviruses.It showed that interspecific divergences of Ascoviruses and TnAV-6b preferred synonymous codons were A/U.