Phylogenetic analysis of the infectious pancreatic necrosis virus (IPNV)from Croatian and Bosnian and Herzegovinian farms

The infectious pancreatic necrosis virus (IPNV) appeared in Croatia several years ago, presumably due to insufficient control of trade with Bosnian and Herzegovinian farms. To clarify the trace of the infection, a detailed research of national isolates together with the isolates from the neighbouring Bosnia and Herzegovina is performed and organ pools from nine Croatian and six Bosnian farms were analysed by virus isolation, ELISA and reverse transcription-polymerase chain reaction (RT-PCR). Phylogenetic analysis of the genogroup III IPNV sequences sorted Croatian and Bosnian isolates on the separate clade, together with the Galician isolate 1146. All Croatian, Bosnian and the Galician isolate 1146 shared unique aminoacid exchange on position 513 (Aspartatic acid D→Glutamic acid E). Additionally, all Bosnian, three Croatian (Cro/VA, Cro 18/11 and Cro 3/11) and Galician isolate 1146 shared one unique silent transition on codon 482. Phylogenetically, those isolates form a subclade as a consequence of this substitution. Retrospectively, we confirmed that trade of fish between those farms has happened on several occasions. Sequence and phylogenetic analysis performed in this study help us to determine the origin and genetic relatedness of viruses as well as to trace the viral source and dissemination.