Latency of Epstein-Barr virus is stabilized by antisense-mediated control of the viral immediate-early gene BZLF-1

J Med Virol. 1999 Dec;59(4):512-9. doi: 10.1002/(sici)1096-9071(199912)59:4<512::aid-jmv15>3.0.co;2-b.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • B-Lymphocytes
  • Cell Line
  • DNA-Binding Proteins / genetics*
  • Epstein-Barr Virus Nuclear Antigens / genetics
  • Gene Expression Regulation, Viral*
  • Herpesvirus 4, Human / genetics*
  • Herpesvirus 4, Human / physiology
  • Plasmids / genetics
  • RNA Splicing
  • RNA, Antisense / physiology*
  • RNA, Viral / physiology*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Trans-Activators / genetics*
  • Transcription, Genetic
  • Viral Proteins / genetics*
  • Virus Latency / genetics*
  • Virus Replication

Substances

  • BZLF1 protein, Herpesvirus 4, Human
  • DNA-Binding Proteins
  • Epstein-Barr Virus Nuclear Antigens
  • RNA, Antisense
  • RNA, Viral
  • Trans-Activators
  • Viral Proteins