Carp edema virus in Ukraine – The evidence for the furthest east presence of CEV genogroup I in Europe

Abstract

Carp edema virus (CEV) is a poxvirus infecting gills of common carp (Cyprinus carpio) and causes a deadly diseasecalled koi sleepy disease (KSD). Currently thanks to higher vigilance and screening for its presence the virus wasconfirmed to be widespread on the European continent and affects both ornamental koi, farmed and feralcommon carp. Phylogenetic research of CEV is however in its infancy. Until recently due to the lack of availablesequence information, the phylogenetic analysis was limited to a p4a gene. Based on this gene two main cladeswere established. The genogroup I clade is of European origin and can be found in farmed or feral common carpin Europe. However, the eastern border of the geographic range of CEV from genogroup I is not yet established,therefore we decided to obtain samples from clinically affected carp from Ukraine. Furthermore, we used se-quences of the DNA binding viral core protein 8 (VP8) and of the uracil DNA glycosylase (UDGS) to confirm theexistence of the genogroups I and II. The results indicate that CEV is highly prevalent in Ukraine. Phylogeneticanalysis using the p4a gene showed that common carps in Ukraine are infected with CEV genogroup I. The twoadditional genes used for the phylogenetic analysis supported the phylogenetic findings. This confirms thatcommon carps in continental Europe are hosts for CEV from the genogroup I and the geographic range for thisvirus is reaching to the most eastern parts of Ukraine.