Architecture of replication compartments formed during Epstein-Barr virus lytic replication

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Epstein-Barr virus (EBV) productive DNA replication is essential for its lytic cycle.
• Replication occurs in specific nuclear sites known as replication compartments.
• Understanding the architecture of these compartments is key to deciphering viral replication mechanisms.

Purpose of the Study:

• To comprehensively analyze the architectural organization of EBV replication compartments during lytic infection.
• To investigate the distribution and function of key viral proteins within these compartments.
• To compare the structure of viral replication factories with cellular DNA replication factories.

Main Methods:

• Immunofluorescence microscopy to visualize protein distribution.
• Analysis of protein association with replicating viral DNA.
• Inhibition of viral DNA replication using phosphonoacetic acid.
• Biochemical fractionation to assess the stability of replication factories.

Main Results:

• BZLF1 binding proteins localized to replicating EBV genomes within compartments.
• BMRF1 polymerase processivity factor distributed homogeneously and bound newly synthesized viral DNA.
• BALF5 polymerase, BALF2, and BBLF2/3 proteins localized as distinct dots within compartments, forming replication factories.
• Viral replication factories were solubilized by DNase I, unlike cellular factories.

Conclusions:

• BMRF1 functions at replication forks and broadly on newly replicated EBV DNA.
• Distinct protein dots represent viral replication factories, differing from cellular factories.
• EBV lytic DNA replication factories are simpler and more relaxed in structure compared to cellular ones.