title: Identification and characterization of two novel transcription units of porcine circovirus 2.
abstract: Porcine circovirus type 2 (PCV2) infection is associated with porcine circovirus-associated diseases in pigs, which is a serious threat to the swine industry worldwide. To date, only three open reading frames (ORFs) within the PCV2 genome have been reported: ORF1 codes for two replicase proteins (Rep and Rep'), ORF2 for the structural protein (Cap), and ORF3 for a protein implicated in cellular apoptosis. In this study, based on transcription analysis of ORF3 mRNA, a potential ORF4 mRNA was detected and characterized by real-time RT-PCR and rapid amplification of cDNA ends analysis. The results indicate that the ORF4 gene is expressed at the level of transcription in the PCV2-infected cells. In addition, a novel ORF3 associated (ORF3') mRNA was identified during virus replication in PK15 cells. Moreover, a 3' poly(A) addition signal sequence (AUUAAA, nt 258-263) was found 10-30 nucleotides upstream of the cleavage site in the novel ORF4 mRNA in the complementary-strand of the PCV2 genome. Furthermore, alternate trans-splicing was identified in the ORF3' mRNA between orientation diverse transcripts with typical GT-AG donor/acceptor junctions. Similar strategies as in this work can be applied to examine the transcription of other potential ORFs in PCV in the future.
authors.affiliation: College of Life Sciences, Zhejiang Sci-Tech University, 2nd Street, Xiasha, Hangzhou, 310018, China.
authors.forename: Zhangzhao
authors.initials: Z
authors.lastname: Gao
authors.forename: Qinfang
authors.initials: Q
authors.lastname: Dong
authors.forename: Yonghou
authors.initials: Y
authors.lastname: Jiang
authors.forename: Tanja
authors.initials: T
authors.lastname: Opriessnig
authors.forename: Jingxiu
authors.initials: J
authors.lastname: Wang
authors.forename: Yanping
authors.initials: Y
authors.lastname: Quan
authors.forename: Zongqi
authors.initials: Z
authors.lastname: Yang
mesh_terms: D000818:Animals; D002460:Cell Line; D017925:Circovirus / Q000235:genetics* / Q000302:isolation & purification; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012367:RNA, Viral / Q000096:biosynthesis / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013552:Swine; D014158:Transcription, Genetic
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D012367:RNA, Viral