Latency of Epstein-Barr virus is stabilized by antisense-mediated control of the viral immediate-early gene BZLF-1.
The ability of the Epstein-Barr virus (EBV) to avoid lytic replication and to establish a latent infection in B-lymphocytes is fundamental for its lifelong persistence and the pathogenesis of various EBV-associated diseases. The viral immediate-early gene BZLF-1 plays a key role for the induction of lytic replication and its activity is strictly regulated on different levels of gene expression. Recently, it was demonstrated that BZLF-1 is also controlled by a posttranscriptional mechanism. Transient synthesis of a mutated competitor RNA saturated this mechanism and caused both expression of the BZLF-1 protein and the induction of lytic viral replication. Using short overlapping fragments of the competitor, it is shown that this control acts on the unspliced primary transcript. RT-PCR demonstrated unspliced BZLF-1 RNA in latently infected B-lymphocytes in the absence of BZLF-1 protein. Due to the complementarity of the gene BZLF-1 and the latency-associated gene EBNA-1 on the opposite strand of the genome, we propose an antisense-mediated mechanism. RNase protection assays demonstrated transcripts in antisense orientation to the BZLF-1 transcript during latency, which comprise a comparable constellation to other herpesviruses. A combined RNAse protection/RT-PCR assay detected the double-stranded hybrid RNA, consisting of the unspliced BZLF-1 transcript and a noncoding intron of the EBNA-1 gene. Binding of BZLF-1 transcripts is suggested to be an important backup control mechanism in addition to transcriptional regulation, stabilizing latency and preventing inappropriate lytic viral replication in vivo.
Prang
N
N
Labor für Molekulare Onkologie, Munich, Germany.
Wolf
H
H
Schwarzmann
F
F
D001402:B-Lymphocytes; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics*; D019309:Epstein-Barr Virus Nuclear Antigens / Q000235:genetics; D015967:Gene Expression Regulation, Viral; D004854:Herpesvirus 4, Human / Q000235:genetics* / Q000502:physiology; D010957:Plasmids / Q000235:genetics; D012326:RNA Splicing; D016372:RNA, Antisense / Q000502:physiology*; D012367:RNA, Viral / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics*; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics*; D017735:Virus Latency / Q000235:genetics*; D014779:Virus Replication
C063676:BZLF1 protein, Herpesvirus 4, Human; D004268:DNA-Binding Proteins; D019309:Epstein-Barr Virus Nuclear Antigens; D016372:RNA, Antisense; D012367:RNA, Viral; D015534:Trans-Activators; D014764:Viral Proteins