title: Roles of E4orf6 and VA I RNA in adenovirus-mediated stimulation of human parvovirus B19 DNA replication and structural gene expression.
abstract: Despite its very narrow tropism for erythroid progenitor cells, human parvovirus B19 (B19V) has recently been shown to replicate and form infectious progeny virus in 293 cells in the presence of early adenoviral functions provided either by infection with adenovirus type 5 or by addition of the pHelper plasmid encoding the E2a, E4orf6, and VA RNA functions. In the present study we dissected the individual influence of these functions on B19V genome replication and expression of structural proteins VP1 and VP2. We show that, in the presence of the constitutively expressed E1A and E1B, E4orf6 alone is able to promote B19V DNA replication, resulting in a concomitant increase in VP expression levels. The stimulatory effects of E4orf6 require the integrity of the BC box motifs, which target cellular proteins such as p53 and the Mre11 DNA repair complex for proteosomal degradation through formation of an E3 ubiquitin ligase complex with E1B. VA RNA also strongly induces VP expression but, in contrast to E4orf6, in a replication-independent manner. This stimulation could be attributed exclusively to the VA I RNA transcript and does not involve major activating effects at the level of the B19V p6 promoter, but the nucleotide residues required for the well-defined pathway of VA I RNA mediated stimulation of translation through functional inactivation of protein kinase R. These data show that the cellular pathways regulating B19V replication may be very similar to those governing the productive cycle of the helper-dependent parvoviruses, the adeno-associated viruses.
authors.affiliation: Institute of Virology, Campus Benjamin Franklin, Charité–University Medicine Berlin, Berlin, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Winter
authors.forename: Kristina
authors.initials: K
authors.lastname: von Kietzell
authors.forename: Regine
authors.initials: R
authors.lastname: Heilbronn
authors.forename: Tanja
authors.initials: T
authors.lastname: Pozzuto
authors.forename: Henry
authors.initials: H
authors.lastname: Fechner
authors.forename: Stefan
authors.initials: S
authors.lastname: Weger
mesh_terms: D000256:Adenoviridae / Q000235:genetics / Q000378:metabolism*; D017504:Adenovirus E4 Proteins / Q000378:metabolism*; D036022:Capsid Proteins / Q000235:genetics*; D002460:Cell Line; D044842:Cullin Proteins / Q000378:metabolism; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis; D015967:Gene Expression Regulation, Viral; D006801:Humans; D046912:Multiprotein Complexes / Q000378:metabolism; D016732:Parvovirus B19, Human / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D011485:Protein Binding; D012367:RNA, Viral / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D019892:eIF-2 Kinase / Q000378:metabolism
chemical_list: D017504:Adenovirus E4 Proteins; C496871:CUL5 protein, human; D036022:Capsid Proteins; D044842:Cullin Proteins; D004279:DNA, Viral; C553318:E4orf6 protein, adenovirus; D046912:Multiprotein Complexes; D012367:RNA, Viral; C052835:adenovirus associated RNA; D044767:Ubiquitin-Protein Ligases; D019892:eIF-2 Kinase