Giant DNA viruses encode a hallmark translation initiation complex of eukaryotic life

This research investigates how giant DNA viruses, specifically Acanthamoeba polyphaga mimivirus (APMV), have evolved their own translation-initiation machinery to hijack host protein synthesis. Scientists discovered that the viral protein R255 is a structural version of the eukaryotic factor eIF4G, which forms a unique vIF4F complex to regulate the production of late-stage viral proteins. Unlike typical eukaryotic systems, the viral component vIF4E has adapted to specifically recognize a unique 2′-O-methylated adenosine modification at the start of viral mRNA. This specialized mechanism allows the virus to maintain high levels of replication even when the host cell is under environmental stress, such as starvation or temperature shifts, which would normally shut down translation. By encoding these evolutionary innovations, giant viruses bypass standard cellular controls to ensure their own fitness and survival in diverse conditions. Therefore, these findings suggest that viruses play a significant role in the molecular evolution of the fundamental processes of life.