Silavirus: a novel noda-like RNA virus discovered in Sydney Harbour marine sediment

Silavirus is a novel, previously-uncharacterized noda-like RNA virus discovered by mining public metatranscriptomic sequencing data with the VIRION pipeline. It was recovered from marine sediment in Port Jackson (Sydney Harbour), Australia (NCBI SRA SRR11786697, BioProject PRJNA630851) — a microbial-ecology dataset in which the virus had never been assembled or identified. Its RNA-dependent RNA polymerase (RdRp) carries the catalytic GDD motif and is strongly divergent from all major databases: 49.6% to the nearest named RdRp (palmDB), 66.0% to the nearest GenBank nr protein (Ripobryn virus), and 56.1% to the nearest sequence in the Serratus catalog of RdRps detected across all public SRA. A maximum-likelihood phylogeny places it on a deep, distinct branch within the noda-like clade. Scope (honest framing): this is a genuine, database-confirmed novel RNA virus lineage, defined — as is standard in environmental RNA-virome studies — by its divergent RdRp (recovered as a partial polymerase, 1,858 nt / 448 aa). The coding-complete genome is not yet recoverable from available public data. This is a candidate-discovery data deposit, not a peer-reviewed publication or a formally ratified ICTV species.