Study the Process of Tegumentation during Virion Maturation of Epstein-Barr Virus

Mature EBV virion contains 6 capsid proteins, 10 glycoproteins and at least 17 tegument proteins. Viron maturation involves complex interactions between capsids, teguments and glycoproteins, and is regulated in a temporal-spatially manner, but is largely unknown in Epstein-Barr virus (EBV) due to the lack of permissive cell culture system for lytic infection. BGLF2 is present in tegument layer of mature virions. Our previous data suggest BGLF2 is important for final envelopment during viral maturation, by interacting with capsid first, later the interaction between BBLF1 and BGLF2 promotes the recruitment of BGLF2-coated capsids to TGN membrane where viral glycoproteins are enriched and final envelopment occur. Knockdown the expression of BGLF2 reduces the production of mature virions that are released into culture medium. The BGLF2-associated viral proteins were identified from coimmunoprecipiation assay followed by proteomic analysis, they are also the components of purified un-enveloped partial-tegumented caspids, suggesting BGLF2 is an interaction hub that promote assembly of teguments and viral maturation. The process of tegumentation occur in the nuclear at first, nuclear tegumentation promote nuclear egress which release capsids into cytoplasm. In the cytoplasm, more tegument proteins are added onto capsid, some of them, such as BGLF2, promote final envelopment by interaction with tegument protein or viral glycoproteins on the TGN. To understand the process of tegumentation, the capsids in different steps of tegumentation will be purified, and the components will be determined by proteomic analysis. Results from this study will reveal where and which the tegument proteins, including BGLF2, are added onto capsids. The interaction between BGLF2 and associated teguments will be further analyzed. In addition, tegument proteins assembly rely on BGLF2 will be determined by analyzing the virion components isolated from BGLF2-null recombinant EBV. Furthermore, the self-assembled capsid from baculovirus expression system will be used to determine the tegument-capsid interaction and sequential events during tegument assembly. It is likely nuclear-assembled teguments regulate the process of nuclear egress. Preliminary data shown BGLF2 interacts with BFRF1 and BFRF2. The involvement of nuclear-assembled teguments and BGLF2 in the process of nuclear egress will be investigated in this study. The results will provide further information regarding to the maturation process of EBV.

Project ID:PC10901-2314
External Project ID:MOST107-2320-B182-004-MY3