ViralEpiBase: a manually curated repository of epitranscriptomic modification sites across viral RNA genomes and virus-encoded transcripts

Post-transcriptional chemical modifications of RNA, collectively termed the epitranscriptome, have emerged as critical regulatory layers governing viral replication, pathogenicity, and host-virus interactions. Despite the rapid accumulation of experimental data on viral RNA modifications, no dedicated, freely accessible resource existed for systematically cataloguing these sites across diverse viral species. Here we present ViralEpiBase, a manually curated database of epitranscriptomic modification sites identified in viral RNA genomes and virus-encoded transcripts at single-nucleotide resolution. ViralEpiBase currently integrates seven chemically distinct RNA modification types: N6-methyladenosine (m6A), N1-methyladenosine (m1A), pseudouridine ({Psi}), 5-methylcytosine (m5C), 2'-O-methylation (2'OMe), inosine and N4-acetylcytidine (ac4C); across 12 viral species encompassing both DNA and RNA viruses of clinical and biological significance. Each entry is linked to its primary literature source or deposited dataset and is retrievable by modification type, genomic coordinates, or viral taxonomy. The database is freely accessible through an intuitive web interface and is updated continuously as new experimental evidence becomes available. ViralEpiBase thus provides the first unified platform dedicated exclusively to viral epitranscriptomics and is designed to facilitate mechanistic investigation of RNA modification functions in viral biology.