epsilonretroviruses

Epsilonretroviruses are a genus of the Retroviridae family, within the subfamily Orthoretrovirinae. Members infect fish, particularly teleosts, and are studied mainly in veterinary virology and fish health monitoring. The best described member is Walleye dermal sarcoma virus (WDSV), which has been associated with seasonal dermal sarcomas in the walleye (Sander vitreus) of North America.

Like other retroviruses, epsilonretroviruses are enveloped, positive-sense single-stranded RNA viruses that reverse-transcribe their genome into DNA and integrate it into the host genome as a provirus during replication. Genomes encode the standard retroviral genes gag, pol, and env, flanked by long terminal repeats that regulate transcription; additional regulatory sequences are present in some species.

Host range is primarily aquatic vertebrates, with disease manifestations described mainly in wild or cultured fish populations. In walleye, WDSV infection is linked to cutaneous sarcomas that appear on the skin and may influence animal health and population dynamics; the disease is of interest to fish health management and aquaculture.

Taxonomy and evolution: Epsilonretroviruses form a distinct lineage within Orthoretrovirinae, separated from other retroviral groups in phylogenetic analyses. They are considered a separate genus within Retroviridae, with multiple species identified primarily in fish.

Transmission and diagnosis: Transmission is thought to be horizontal through contact or water in aquatic environments; detection relies on molecular assays, histopathology, and research-oriented serology. Pathogenesis and ecology are not as well characterized as for some other retroviral genera.