Genotyping and molecular characterization of the infectious pancreatic necrosis virus isolates detected in some Iranian trout farms

Infectious pancreatic necrosis is caused by IPNV virus that represented by various strains with different virulence linked to some motifs of the VP2 capsid. In this study (2018-2019), we screened some suspected Iranian trout farms for IPNV, and the genotype and virulence motifs of the positive samples were characterized. The causative agents of two outbreaks in trout farms of Kermanshah and Hamedan provinces in Iran were diagnosed as IPNV by RT-PCR assay. Phylogenetic analysis of VP2 gene revealed the detected IPNV isolates belonged to the Genotype 5 (Sp serotype) with close identity (> 99%) with European, Turkish, as well as previously reported Iranian isolates. Characterization of VP2 from both outbreaks has also shown the detected isolates have proline and threonine at amino acid residues 217 and 221, respectively, which are associated with low pathogenicity. In conclusion, the IPNV isolates from some Iranian trout farms (Kermanshah and Hamedan provinces) are of Sp serotype (Genotype 5) that despite P217T221 motif show moderate virulence, and may have originated from Europe via eyed eggs.