The first instance of HPR-deleted ISAV detection in eviscerated, fresh salmon at a Chinese entry-exit port

Abstract

Infectious salmon anemia virus (ISAV) is a serious epidemic in fish that is characterized by severe anemia and variable hemorrhaging, and is one of the most important pathogens that China tests for in imported salmon and salmon products. The Sichuan Entry-Exit Inspection and Quarantine Bureau (SCCIQ) tested a total of 79 batches of salmonid products from Norway for ISAV during 2015, using the TaqMan RT-qPCR targeting segment 7 and conventional RT-PCR with segment 6 HPR (highly polymorphic region) primers, and by virus isolation attempts using Atlantic salmon kidney (ASK) cell line monolayers. Only one batch of eviscerated, fresh salmon (imported random sample 2015CD0652) was shown to be suspected positive for HPR-deleted ISAV. The sequence from the conventional PCR product was analyzed by phylogenetic alignment, and the results show that 2015CD0652 has a 51bp deletion in the HPR, and a close relationship with ISAV9 and 9/93 HPR 3 isolates from Norway; however, the virus isolation attempts on the sample were negative. This is the first published report of the detection of HPR-deleted ISAV sequences in salmon flesh rather than salmon viscera in a Chinese entry-exit port, which suggests the need for heightened vigilance regarding imported fresh salmon.