title: Parainfluenza virus chimeric mini-replicons indicate a novel regulatory element in the leader promoter.
abstract: Gene expression of paramyxoviruses is regulated by genome-encoded cis-acting elements; however, whether all the required elements for viral growth have been identified is not clear. Using a mini-replicon system, it has been shown that human parainfluenza virus type 2 (hPIV2) polymerase can recognize the promoter elements of parainfluenza virus type 5 (PIV5), but reporter activity is lower in this case. We constructed a series of luciferase-encoding chimeric PIV2/5 mini-genomes that are basically hPIV2, but whose leader (le), mRNA start signal and trailer sequence are partially replaced with those of PIV5. Studies of the chimeric PIV2/5 mini-replicons demonstrated that replacement of hPIV2 le with PIV5 le results in remarkably weak luciferase expression. Further mutagenesis identified the responsible region as positions 25-30 of the PIV5 le. Using recombinant hPIV2, the impact of this region on viral life cycles was assessed. Insertion of the mutation at this region facilitated viral growth, genomic replication and mRNA transcription at the early stage of infection, which elicited severe cell damage. In contrast, at the late infection stage it caused a reduction in viral transcription. Here, we identify a novel cis-acting element in the internal region of an le sequence that is involved in the regulation of polymerase, and which contributes to maintaining a balance between viral growth and cytotoxicity.
authors.affiliation: Department of Microbiology, School of Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Department of Microbiology, School of Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ohta
authors.affiliation: Department of Microbiology, School of Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Goto
authors.affiliation: Department of Microbiology, School of Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan.
authors.forename: Machiko
authors.initials: M
authors.lastname: Nishio
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics*; D001483:Base Sequence; D045744:Cell Line, Tumor; D002678:Chimera / Q000235:genetics*; D016679:Genome, Viral / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D010223:Parainfluenza Virus 2, Human / Q000235:genetics* / Q000254:growth & development; D045402:Parainfluenza Virus 5 / Q000235:genetics* / Q000254:growth & development; D018184:Paramyxoviridae Infections / Q000821:virology; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D012093:Replicon / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics; D014779:Virus Replication / Q000235:genetics
chemical_list: D020121:5' Untranslated Regions; D012367:RNA, Viral; D012324:RNA-Dependent RNA Polymerase