First Detection of Dangerous Fish Pathogen Cyprinid Herpesvirus 2 (CyHV-2) in Russia

Since the beginning of the 21st century, the multiple cases of mass mortalities in populations of fish of Carassius auratus complex (Cyprinidae) have been noted from different regions of European part of Russia; however, the causes of those mortalities remained unexplained. We focused on mortality in a population of C. auratus complex in Kiovo Lake in the upper part of the Volga River basin. The presence of the emergent fish pathogen cyprinid herpesvirus 2 (CyHV-2) was confirmed by PCR in gill filament and muscle tissues of dead C. auratus complex individuals, but not in living conspecifics without clinical signs of diseases. This is the first detection of CyHV-2 in Russia. We encourage urgent investigations of possible links between the detected pathogen and mortality events in populations of C. auratus complex within Russia. Perspectives of using of CyHV-2 as a tool for biocontrol of C. auratus complex, one of the Top-100 invasive species in Russia, are discussed.