The presence of translation-related proteins has long been seen as a critical distinction between viruses and cellular life, the discovery of giant viruses has challenged this standard. We prove that the potential eukaryotic translation initiation factor 4A (eIF4A, Mb0671) encoded by the Megavirus baoshan (M. baoshan), a member of the Mimiviridae family, possesses ATPase activity and RNA-binding capacity. Mb0671 is important for viral adaptation to the host, localizes to the cytoplasm, and is found in mature virions. Proteomics reveals that Mb0671 can manipulate host protein synthesis, compared to wild-type cells, the cellular proteins that are significantly upregulated in A. castellaniia cells overexpressing Mb0671 are significantly enriched in the spliceosome, biosynthesis of amino acids, ribosome biogenesis in eukaryotes, SNARE interactions in vesicular transport, DNA replication, autophagy and mTOR signaling pathway. Proteomics also revealed Mb0671 plays an important role in RNA processing and transport, gene expression regulation in host cells. Proteomics reveals that overexpression of Mb0671 significantly affects the synthesis of viral proteins. Indirect interactions between Mb0671 and the host's eIF4A, along with other interactions primarily with ribosomal and translation-related proteins, suggest that Mb0671 may form a complex with host translation proteins to perform translation functions. Our findings indicate that the virus-encoded translation factor Mb0671 plays an important role in viral protein synthesis, suggesting that these unusual viruses may possess a special translation mechanism in which Mb0671 could play a key role.