title: Spliced spleen necrosis virus vector RNA is not encapsidated: implications for retroviral replication and vector design.
abstract: RNA splicing is a complex event in the retroviral life cycle and can involve multiple steps, as well as cis-acting sequences, to maintain a proper balance of spliced and unspliced viral RNA for translation and encapsidation. The retroviral RNA can be processed by cellular machinery and enables the removal of intronic sequences. We aimed to utilize the removal of a synthetic intron for targeted gene expression. To analyze intron removal and gene expression, we have constructed a novel self-inactivating gene-activating (SIGA) vector for potential universal gene therapy. New vectors for gene therapy are necessary for safe and effective gene delivery in humans. The SIGA vector is derived from spleen necrosis virus (SNV), which is an avian reticuloendotheliosis virus. The vector was designed so that expression of a therapeutic gene is blocked in helper cell lines due to an intervening sequence containing various blocks in transcription and translation. However, after one round of retroviral replication, the intervening sequence should be removed by the cellular machinery and the therapeutic gene will be selectively expressed in target cells. Our studies show that the intervening sequence in SIGA vector RNA is partially spliced. However, spliced vector RNA was not transduced to target cells. Previous studies showed that an infectious SNV vector enabled transduction of spliced RNA. However, yet-undefined differences in infectious and replication-deficient retroviral replication may have an effect on the transduction of spliced RNA. The results of this study present key information on spliced RNA and its encapsidation, as well as data for the construction of a new generation of SNV-derived retroviral vectors.
authors.affiliation: Center for Human Virology and Biodefense, Thomas Jefferson University, Philadelphia, PA 19107, USA.
authors.forename: Adrienne
authors.initials: A
authors.lastname: Goodrich
authors.forename: Zahida
authors.initials: Z
authors.lastname: Parveen
authors.forename: Ralph
authors.initials: R
authors.lastname: Dornburg
authors.forename: Matthias J
authors.initials: MJ
authors.lastname: Schnell
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Pomerantz
mesh_terms: D000818:Animals; D015139:Blotting, Southern; D002460:Cell Line; D045744:Cell Line, Tumor; D004247:DNA / Q000737:chemistry; D004285:Dogs; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D006801:Humans; D007438:Introns; D008957:Models, Genetic; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012313:RNA / Q000378:metabolism; D012326:RNA Splicing; D012367:RNA, Viral; D017986:Reticuloendotheliosis Viruses, Avian / Q000235:genetics*; D012190:Retroviridae / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014779:Virus Replication
chemical_list: D012367:RNA, Viral; D012313:RNA; D004247:DNA