Epstein-Barr virus genome packaging factors accumulate in BMRF1-cores within viral replication compartments

PLoS One. 2019 Sep 13;14(9):e0222519. doi: 10.1371/journal.pone.0222519. eCollection 2019.

Abstract

Productive replication of Epstein-Barr virus (EBV) during the lytic cycle occurs in discrete sites within nuclei, termed replication compartments. We previously proposed that replication compartments consist of two subnuclear domains: "ongoing replication foci" and "BMRF1-cores". Viral genome replication takes place in ongoing replication foci, which are enriched with viral replication proteins, such as BALF5 and BALF2. Amplified DNA and BMRF1 protein accumulate in BMRF1-cores, which are surrounded by ongoing replication foci. We here determined the locations of procapsid and genome-packaging proteins of EBV via three-dimensional (3D) surface reconstruction and correlative fluorescence microscopy-electron microscopy (FM-EM). The results revealed that viral factors required for DNA packaging, such as BGLF1, BVRF1, and BFLF1 proteins, are located in the innermost subdomains of the BMRF1-cores. In contrast, capsid structural proteins, such as BBRF1, BORF1, BDLF1, and BVRF2, were found both outside and inside the BMRF1-cores. Based on these observations, we propose a model in which viral procapsids are assembled outside the BMRF1-cores and subsequently migrate therein, where viral DNA encapsidation occurs. To our knowledge, this is the first report describing capsid assembly sites in relation to EBV replication compartments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Viral / genetics*
  • Cell Line
  • Cell Nucleus / genetics
  • DNA Replication / genetics
  • DNA, Viral / genetics
  • DNA-Binding Proteins / genetics
  • Genome, Viral / genetics*
  • Herpesvirus 4, Human / genetics*
  • Humans
  • Viral Proteins / genetics
  • Virus Replication / genetics*

Substances

  • Antigens, Viral
  • DNA, Viral
  • DNA-Binding Proteins
  • Epstein-Barr virus early antigen diffuse component
  • Viral Proteins

Grants and funding

This work was supported by grants-in-aid for scientific research from the Ministry of Education, Science, Sports, Culture and Technology of Japan (12J04062, 17J06368, 18K17362 to A. S., 24659213 to T.T., 19K07580 to T. M.), and Japan Agency for Medical Research, Development (Japanese Initiative for Progress of Research on Infectious Disease for Global Epidemic, JP17fm0208016 to T.M.), and the Takeda Science Foundation (to T.M.). The funders had no role in the study.