Two new viruses, Rhombovirus hippoglossi (Alpharhabdovirinae) and Piscisplanusvirus hippoglossi (Feraresvirinae), present in Atlantic halibut (Hippoglossus hippoglossus) larvae during mortalities in commercial production

The nearly complete genomes of a new paramyxovirus (Piscisplanusvirus hippoglossi, PpH) and a new rhabdovirus (Rhombovirus hippoglossi, RoH) were obtained from Atlantic halibut fry suffering mortalities during start feeding and weaning to dry feed. The genome of the paramyxovirus is 15,159 nucleotides in length and consists of eight putative genes coding for nucleoprotein (N), putative unknown protein (U 1 ), phospho-protein (P), cysteine-rich protein (V), matrix protein (M), fusion protein (F), hemagglutinin-neuraminidase protein (HV), and large polymerase protein (L). The gene junctions have conserved transcription start and stop signal sequences and intergenic regions. Comparisons of the amino acid sequences and phylogenetic analyses using the L protein sequence show that PpH represents a putative new genus within sub-family Feraresvirinae. The genome of the rhabdovirus is 11,140 nucleotides long and consists of the canonical N-P-M-G-L proteins found in other rhabdovirus, in addition to a putative ORF encoding an unknown protein (U1). The transcription termination and the start sequences are conserved in the genome and separated by four nucleotide intergenic sequences. Based on analyses of amino acid sequences RoH belongs within Alpharhabdovirinae constituting a putative new genus, Rhombovirus. This is the first description of a paramyxovirus and a rhabdovirus obtained from Atlantic halibut ( Hippoglossus hippoglossus ). The rhabdovirus (RoH) is associated with liver pathology while it has not been possible to identify any pathology associated with the paramyxovirus. Both viruses are present in start-feeding larvae and larvae during weaning to dry feed in tanks with mortalities.