Characterisation of the putative nucleoprotein gene of infectious salmon anaemia virus (ISAV)

A gene encoding the putative nucleoprotein (NP) of infectious salmon anaemia virus (ISAV), a commercially important salmonid Orthomyxovirus, has been identified. cDNA obtained from a subtractive cDNA library bound specifically to RNA extracted from ISAV-infected SHK-1 cell cultures. The 5′ and 3′ ends of the gene were amplified using RACE PCR and a full length open reading frame (ORF) of 1851 nt identified encoding a predicted protein of 616 amino acids. No significant homology of this sequence with any other orthomyxovirus nucleoprotein was identifiable using BLAST or FASTA-based database searches. The ISAV-protein was however identified as a nucleoprotein based on its characteristic amino-acid composition. Furthermore the conserved sequence 5′ GCAAAGA 3′ was identified preceding the ORF, as has been identified in all other ISAV-genes characterised to date.