Abstract
Translation is a sine qua non process for life as we know it. Translation factors (TFs) and tRNAs are rare among viruses but are commonly found in giant viruses of the class Megaviricetes. In this study, we explored the diversity and distribution of tRNAs in giant viruses that were isolated and replicated in amoebae (phylum Amoebozoa), and investigated the evolutionary history of TFs to gain insights into their origins in these viruses. We analyzed the genomes of 77 isolated giant viruses, 52 of which contained at least 1 tRNA. In most of these viruses, tRNA sequences are dispersed throughout the genome, except in Tupanviruses and Yasmineviruses, where most tRNAs are clustered in specific genomic islands. The tRNAs in giant viruses often contain introns, with 73.1% of the genomes exhibiting at least one intronic region in these genes. Codon usage bias (CUB) analysis of various giant viruses revealed at least two distinct patterns of codon preferences among closely related viruses. We did not observe a clear correlation between the presence of tRNAs and CUB in giant viruses. Due to the limited size of these genes, we could not confidently investigate their phylogenetic relationships. However, phylogenetic analysis of TFs found in giant viruses often position these viruses as sister groups or embedded between different eukaryotic taxa with high statistical support. Overall, our findings reinforce the complexity of key components of the translation apparatus in different members of Nucleocytoviricota isolated from different regions of Earth.