New ranavirus lineage tied to severe disease in Great Barrier Reef wrasses

A newly published Frontiers in Veterinary Science study reports the discovery of a novel ranavirus isolate, dubbed Macropharyngodon choati ranavirus, in captive ornamental Choat’s wrasses collected from the Great Barrier Reef. Investigators from the University of Sydney and Cairns Marine linked unexplained mortalities to this virus after finding acute tubulointerstitial kidney necrosis on histopathology, cytopathic effects in bluegill fry cell culture, PCR-positive tissues, and very high viral transcript abundance, especially in spleen samples. Phylogenetic analysis placed the virus within Ranavirus micropterus1, but in a distinct wrasse-associated lineage, making this the first reported evidence of Ranavirus micropterus1 disease in Australian reef fishes. (frontiersin.org)

Why it matters: For veterinary professionals working in aquatic, zoo, wildlife, or ornamental settings, the report expands the known host and geographic range of a ranavirus group already associated with significant disease events in fish. The authors argue that wild wrasses may be natural hosts and note that related viruses have likely moved through both aquaculture and the ornamental fish trade. That matters because ranaviruses can spread through water and contact, persist in aquatic environments, and have no specific treatment or vaccine, which raises the stakes for quarantine, diagnostics, necropsy workups, and pathogen surveillance in imported or wild-caught marine ornamentals. WOAH notes that ranaviruses are an important concern across fish, amphibian, and reptile populations, and Cornell Wildlife Health Lab emphasizes that biosecurity is central because environmental persistence can support ongoing transmission. (frontiersin.org)

What to watch: Expect follow-up work on prevalence in wild Great Barrier Reef fishes, transmission pathways, and whether surveillance or trade-health screening protocols for ornamental marine species begin to change in response to this finding. (frontiersin.org)