Large-scale mining of publicly available RNA-sequencing datasets revealed a previously cryptic clade of plant-associated negative-sense RNA viruses. The analyses assembled 87 complete or near-complete genomes associated with 75 distinct plant hosts, expanding the known diversity of this group by roughly 40-fold relative to prior records. The study combined sequence detection, phylogenetic reconstruction, structural prediction, and host-association analysis to characterize these viruses beyond initial detection.
The authors refer to these agents as lispi-like viruses and emphasize that integrating complementary computational approaches can move viral dark matter from mere detection to evolutionary and functional interpretation.
All assembled genomes share a conserved four-cistron architecture organized in the order 3'-N-P2-P3-L-5'. This consistent layout suggests a shared genomic blueprint across the clade and provides a framework for comparative functional annotation of the encoded proteins.
The conserved gene order supports a cohesive grouping distinct from other negative-sense RNA virus families and guided downstream structural and phylogenetic analyses.
Predicted structures indicate that P1 corresponds to a canonical negative-strand RNA virus nucleocapsid (N) protein fold. Structural models resolve features consistent with RNA binding: conserved RNA-interacting residues and a predicted RNA-packaging configuration were identified.
These observations support P1’s role in genomic RNA encapsidation and formation of ribonucleoprotein complexes, as expected for nucleocapsid proteins in negative-sense RNA viruses.
P2 is notably the most divergent protein across the four cistrons. Structural prediction yields heterogeneous results: a subset of P2 structures resemble the fold of ITPase/HAM1 family proteins, while many P2 sequences remain highly atypical and do not match well-characterized enzymatic folds.
The divergence of P2 suggests potential functional variability between genera or specialized roles that are not conserved across the entire clade. The source does not report experimental validation of P2 activities.
P3 consistently forms a trimeric coiled-coil architecture across predicted structures. This arrangement is reminiscent of a viral fusion-protein stalk, suggesting a role in multimeric protein interactions or virion architecture.
However, P3 lacks the family-wide sequence hallmarks expected for canonical membrane glycoproteins, indicating that it may perform fusion-related or structural roles through a noncanonical mechanism or that additional, unrecognized proteins mediate membrane interactions.
P4 contains a structurally resolved Mononegavirales-type RNA-dependent RNA polymerase (RdRp) core. Structural models reveal invariant catalytic motifs, including the characteristic GDN signature, confirming P4’s identity as the genome-encoded polymerase.
While the polymerase core is conserved, accessory regions flanking the core are substantially more divergent, implying potential genus-specific accessory functions or regulatory differences in replication complexes.
Phylogenetic reconstruction places the lispi-like viruses as a distinct, well-supported monophyletic lineage sister to the predominantly invertebrate-associated Lispiviridae. Based on this placement and combined genomic and structural evidence, the authors propose recognition of this lineage as a new family, Masuviridae, subdivided into 15 tentative genera.
Genus-level clustering corresponds to clear sequence divergence and is accompanied by differences in predicted biology and host association, supporting the taxonomic split at the genus level.
Retrospective screening of public sequencing libraries identified lispi-like virus sequences in 1,536 libraries. These libraries represent 134 plant species across 11 plant families and span 182 geographic locations, indicating a geographically widespread and substantial cryptic virome among plants.
Host-association analyses reveal variation in host range among genera: some genera show strong specialization to particular plant hosts, while others appear to infect a broader set of plant species. The source summary does not provide specific species-level host lists or prevalence metrics beyond the numbers reported above.
The work illustrates how coupling large-scale transcriptomic mining with structural prediction and phylogenetics can transform detection of divergent viral sequences into richer evolutionary and functional hypotheses. The identification of conserved genome architecture, RdRp catalytic motifs, and characteristic structural features supports the placement of these viruses as a deeply divergent lineage of negative-sense RNA viruses adapted to plants.
The study proposes the formal recognition of Masuviridae and delineates 15 tentative genera, but experimental characterization (infectivity, vector relationships, and functional assays of predicted proteins) will be required to validate biological roles and taxonomy. Specific methodological parameters, experimental validations, and per-sequence metadata were not reported in the source summary and therefore are not included here.