Abstract
Infectious salmon anaemia virus (ISAV) is the cause of an important waterborne disease of farmed Atlantic salmon. Detection of virus in water samples may constitute an alternative method to sacrificing fish for surveillance of fish populations for the presence of ISA-virus. We aimed to evaluate different membrane filters and buffers for concentration and recovery of ISAV in seawater, prior to molecular detection. One litre each of artificial and natural seawater was spiked with ISAV, followed by concentration with different filters and subsequent elution with different buffers. The negatively charged MF hydrophilic membrane filter, combined with NucliSENS® lysis buffer, presented the highest ISAV recovery percentages with 12.5 ± 1.3% by RT-qPCR and 31.7 ± 10.7% by RT-ddPCR. For the positively charged 1 MDS Zeta Plus® Virosorb® membrane filter, combined with NucliSENS® lysis buffer, the ISAV recovery percentages were 3.4 ± 0.1% by RT-qPCR and 10.8 ± 14.2% by RT-ddPCR. The limits of quantification (LOQ) were estimated to be 2.2 x 103 ISAV copies/L of natural seawater for both RT-qPCR and RT-ddPCR. The ISAV concentration method was more efficient in natural seawater.
Highlights
Infectious salmon anaemia virus (ISAV) is a negative sense single-stranded RNA virus that belongs to the family Orthomyxoviridae, genus Isavirus [1,2,3,4]
The same filters, buffers and concentration procedures described previously [21] were used to concentrate ISAV from 1L of artificial seawater or natural seawater spiked with ISAV
This study investigated the use of different filters and buffers for concentration and detection of ISAV in seawater, using qPCR assays
Summary
Infectious salmon anaemia virus (ISAV) is a negative sense single-stranded RNA virus that belongs to the family Orthomyxoviridae, genus Isavirus [1,2,3,4]. ISAV is the causative agent of infectious salmon anaemia (ISA), which is arguably one of the most important waterborne viral disease of farmed Atlantic salmon [5,6,7,8]. The mechanisms of ISAV transmission are not fully understood; the majority of ISA disease outbreaks occur in the seawater production phase, and shedding of virus from the mucus and faeces of infected fish into seawater has been suggested as a major source of spread [6]. ISA disease outbreaks caused by horizontal transfer of the virulent virus have been reported in several studies, indicating possibilities of virus spread between farms [10,11,12,13]. Routine surveillance of seawater for the presence of ISAV can be a vital supplement to current
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