"Fishing" salmon viruses
Viruses are of notorious reputation because of their ability to change continuously in order to adjust to their environment. Through this process their survival and multiplication are secured and their pathogens can spread undisturbed. The challenging research field of emerging viral diseases and their causal agents has attracted researchers' attention. Specifically, salmon pancreas disease (SPD), first identified in farmed fish as an infection from the corresponding virus (SPDV), drew the interest of a European network partners. The research performed revealed that SPDV is very similar to the causal virus of sleeping disease (SDV) that occurs in farmed trout. In fact, SPDV and SDV were shown to have evolved from the same virus species, the alphaviruses. Hence, they were both registered with the name salmonid alphavirus (SAV). Members of the alphavirus genus are encountered in mammals and serve as eukaryotic expression vectors in molecular biology. The network partners directed their efforts towards investigating SAV with the aim to derive new knowledge about pathogenesis and virus pathogenicity. Their ultimate aim was to produce quantitative or semi-quantitative estimates of virus RNA in experimental and clinical samples. For this purpose, they employed the real time reverse transcriptase polymerase chain reaction (RT-PCR) technique to develop a novel RT-PCR test with increased sensitivity to detect SAV RNA. The new test was further optimised and validated using standard cell-cultured or serum infected samples. The results showed that its detection capacity was improved compared to the conventional methods quantifying the virus titre as equal to, or less than 1.5 TCID 50 (50% tissue culture infective dose). The test was also evaluated in the heart tissue samples with good results. Further collaboration is sought to make the most of the new test's potential for accurate diagnosis of diseases with SAV as causal agent.
