DAO 66:181-185 (2005)  -  doi:10.3354/dao066181

Comparison of lethal versus non-lethal sample sources for the detection of infectious salmon anemia virus (ISAV)

C. Giray1,*, H. M. Opitz2, S. MacLean3, D. Bouchard1

1Micro Technologies, 41 Main Street, Richmond, Maine 04357, USA
2Animal Disease Diagnostic Laboratory, University of Maine, Orono, Maine 04469-5735, USA
3USDOC/NOAA/NMFS/NEFSC, 28 Tarzwell Drive, Narragansett, Rhode Island 02882-1199, USA

ABSTRACT: The emergence of infectious salmon anemia virus (ISAV) in Canada and the USA has led to the establishment of ISAV surveillance programs for cultured Atlantic salmon (Salmo salar L.) and wild fish species, including Atlantic salmon. Current testing procedures for ISAV consist of viral culture, reverse-transcription polymerase chain reaction (RT-PCR) and indirect fluorescent antibody testing (IFAT), and require lethal sampling. As the focus of this study, blood was evaluated as a possible non-lethal sample source for ISAV diagnostic screening by viral culture and RT-PCR. Tissue samples (consisting of kidney/spleen for viral culture or kidney only for RT-PCR), blood and, to a lesser extent, mucus were tested from Atlantic salmon survivors of laboratory ISAV infection trials and moribund fish from marine salmon grow-out facilities participating in a USDA-sponsored surveillance program. The trial fish represented a potential carrier population, while the surveillance fish were composed of moribund individuals from ISA clinical sites. Sample sources and diagnostic techniques were compared. Blood compared well to tissue samples for viral culture and produced a greater number of positives than did kidney samples for ISAV detection by RT-PCR. RT-PCR using both kidney and blood samples was determined to be a more sensitive assay than viral isolation. Mucus did not perform well in either assay compared to the other sample sources. Blood appears to be a reliable non-lethal sample source for the detection of ISAV by viral culture and RT-PCR in both moribund and asymptomatic fish.


KEY WORDS: ISAV · Non-lethal sampling · Carrier populations · Blood · RT-PCR · Virus isolation


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