Investigation of starry sturgeon Acipencer stellatus in the Black Sea and Sea of Azov for AcIV-E infection

Abstract

Specific sturgeon nucleocytoplasmic large DNA viruses (sNCLDV) infect several species of the Acipenseridae family. sNCLDV have previously been referred to as unclassified members of the family Iridoviridae. They have recently been moved from Iridoviridae to Mimiviridae family. One of these viruses, Acipenser iridovirus-European (AcIV-E), is present in farms across Europe where it has occasionally caused mild to severe losses in sturgeons. In this study, we provide data on AcIV-E search in a susceptible species such as starry sturgeon (Acipencer stellatus) from the Black sea and Sea of Azov. In 2020, starry sturgeons were sampled in Odessa region of the Black Sea and Zaporizhzhia region of the Sea of Azov. None of the sampled fish demonstrated pathological signs of disease and were healthy upon visual observation all individuals. Total DNA was extracted and submitted to a generic PCR targeting different fragments of major capsid protein (MCP) gene of AcIV-E. No virus-specific products were obtained in any starry sturgeon sample from both seas, while the expected products of MCP gene fragments as well as the fragments of beta-actin gene in control reactions were successfully amplified using fish and viral DNA of AcIV-E isolated from Siberian sturgeon in 2018–2019. Although AcIV-E is difficult to identify in asymptomatic wild fish, but it probably can play a role in starry sturgeon pathology across the Black Sea basin. A high risk of virus spread to wild populations is possible since this virus was identified in sturgeon farms upstream the Dnipro river. Therefore, AcIV-E, even in the presence of other pathogens, should be studied in sturgeon hatcheries as well as in possible vectors of disease, but the huge area of inspection could be a challenge.