Hiding in plain sight: genomic characterization of a novel nackednavirus and evidence of diverse adomaviruses in a hyperpigmented lesion of a largemouth bass (micropterus salmoides)

Authors: RAINES, CLAYTON - Us Geological Survey (USGS); ODENKIRK, JOHN - Virginia Department Wildlife Resources; ISEL, MICHAEL - Virginia Department Wildlife Resources; MAZIK, PATRICIA - Us Geological Survey (USGS); BIGGS, MORGAN - Us Geological Survey (USGS); Iwanowicz, Luke

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2025
Publication Date: 8/28/2025
Citation: Raines, C.D., Odenkirk, J., Isel, M., Mazik, P., Biggs, M., Iwanowicz, L.R. 2025. Hiding in plain sight: genomic characterization of a novel nackednavirus and evidence of diverse adomaviruses in a hyperpigmented lesion of a largemouth bass (micropterus salmoides). Viruses. 17(9). Article 1173. https://doi.org/10.3390/v17091173.
DOI: https://doi.org/10.3390/v17091173

Interpretive Summary: Largemouth bass are the most important warmwater game fishes in the United States. They are also part of a growing aquaculture industry. Despite the significant socioeconomic importance of this species, our understanding of viral diseases is limited. Here we identify novel viruses associated with a skin disease in largemouth bass. While the significance of these viruses is largely unknown, establishing an understanding of host-based microbial ecology informs subsequent biosecurity and disease management efforts.

Technical Abstract: Due to their popularity as a sportfish and as an aquaculture species, primary and secondary pathogens of largemouth bass (LMB; Micropterus salmoides) are better known in this species than other non-model fish species.well-studied. While numerous bacterial pathogens of bass have been described, there is a paucity of viral research in this species. At present the only described viruses associated with largemouth bass are largemouth bass reovirus (LMBRV), Micropterus salmoides reovirus (MeReV) the iridovirus, largemouth bass virus (LMBV), Micropterus salmoides rhabdovirus (MSRV), and the recently identified Micropterus salmoides adomavirus (MsA-1). The causal relationship between the reoviruses and clinical disease is ambiguous, which is typical of this family of orphan viruses. LMBV was first discovered in 1991 and has been routinely ascribed as the causative pathogen in LMB mortalities. It has also been demonstrated to be a pathogen of other black basses including smallmouth bass (SMB; Micropterus dolomieu). More recently, MSRV was also identified as a primary pathogen of LMB, and at present, only LMBV and MSRV are considered in cases of LMB mortality events. However, this likely reflects the black-box containing the universe of uncharacterized viruses of this host rather than an indication of a scarcity of primary pathogens. Advances in discovery and diagnostic capabilities using “next generation sequencing”, coupled with de novo assembly approaches, have augmented surveillance efforts, and subsequently lead to the discovery of numerous novel viruses. Here we present evidence of three novel viruses from a single skin sample collected from a melanistic lesion of a LMB with blotchy bass syndrome from Little Hunting Creek, VA. These viruses represent two novel groups of viruses known as adomaviruses and nackednaviruses. Both are markedly understudied and of unknown significance to fish health. This work highlights that the diversity of viruses associated with LMB is poorly understood. Application of such de novo sequencing methods presents an opportunity to explore a new frontier of host-pathogen relationships and microbes associated with changing environments.