A New Lineage of Perch Rhabdovirus Associated with Mortalities of Farmed Perch

Nearly complete genome sequence of a Perhabdovirus isolated on European perch (Perca fluviatilis)

We report a nearly full-length genome of a Perhabdovirus isolated in 2022 on perch on a French farm. This virus is genetically related to virus 20/43, which was associated with an outbreak of perch on a farm in France in 2019. Both viruses represent a specific lineage of perch rhabdovirus.

Further spread of perch rhabdovirus on European percid farms

Variants of perch rhabdovirus (PRV) circulate across European percid farms via the fish trade. To trace their circulation, they are usually isolated by cell culture and subsequently identified genetically by sequencing partial or complete genes. Here, a newly developed nested PCR-based method was used to amplify and sequence the complete N and P genes directly from clinical samples obtained during an outbreak on a farm as well as from four batches of fish sampled from two other farms in another country. In an attempt to trace the origin of the five detected viruses, their N and P sequences were concatenated and compared with related viruses. One virus found in pike-perch was highly related to a virus isolated in 2016 in Belgium. Two other viruses detected on a single farm were distinct from one another, with one being almost identical to another virus isolated in 2016 in Belgium and the other being more closely related to a subgroup with different origins, France and Belgium. Two other viruses found in perch from a third farm were identical and were more related to a subgroup of viruses isolated in France. Identifying variants by a direct PCR approach will help to prevent further dissemination in farms.