Molecular detection of a novel cyprinid herpesvirus in roach (Rutilus rutilus) and asp (Leuciscus aspius) showing typical signs of carp pox disease

Abstract

In the early spring of 2018, in Lake Balaton (Hungary), a roach (Rutilus rutilus) and an asp (Leuciscus aspius) were found in an fish trap at the outlet of the river Sió showing typical signs of the so-called carp pox disease, such as foci of epidermal hyperplasia on the head and the whole body surface, including the fins. Molecular tests revealed the presence of the DNA of an unknown fish herpesvirus. Three genes encoding the DNA-dependent DNA polymerase, major capsid protein and ATPase subunit of terminase were amplified and sequenced from the alloherpesviral genome. The gene sequences of the viruses obtained from the two different fish species shared 94.4% nucleotide sequence identity (98.1% amino acid sequence identity), suggesting that they belong to the same virus species. Phylogenetic analysis based on the DNA polymerase (and the concatenated sequences of the amplified genes, as well) implied that the detected virus belongs to the genus Cyprinivirus within the family Alloherpesviridae. The sequences of the novel alloherpesvirus diverge from those of the five cyprinivirus species described previously, so it putatively represents the sixth virus species in the genus.

Partial genetic characterisation of a novel alloherpesvirus detected by PCR in a farmed wels catfish (Silurus glanis)

“…This is an interesting fact, especially considering that another virus from the same host (AciHV-1) occupies a long, solitary branch in the phylogeny tree reconstructions, so that its genus affiliation has not yet been determined (Kurobe et al, 2008). The genus Cyprinivirus encompasses a number of herpes-like viruses of the common carp (Cyprinus carpio) along with other HVs, discovered in closely, or in a couple of cases in more distantly, related fishes (Davison et al, 2013;Borzák et al, 2020;Sellyei et al, 2020). Cyprinid HV-1 (CyHV-1) is the aetiological agent of the so-called carp pox disease, frequently seen among farmed carp.…”