Development of a widely applicable positive control strategy to support detection of infectious salmon anaemia virus (ISAV) using Taqman real-time PCR

Real-time PCR assays are being increasingly applied to the detection of fish pathogens due to their sensitivity, specificity and potential for high throughput sample processing. Such assays allow for the ready and efficient inclusion of appropriate quality controls which are fundamental to scientific integrity and to satisfying the demands of diagnostic test accreditation. In this article, we report development of a universal positive control strategy for real-time PCR assays, which has been used to support and improve a previously published method for detection of infectious salmon anaemia virus (ISAV). The strategy employed uses an RNA mimic template, which is based on the ISAV segment 8 target sequence but includes an artificial universal positive control sequence. Inclusion of this sequence, which is targeted by a second specific probe carrying a different fluorophore to the primary assay, allows for convenient screening of all real-time PCR reactions for the presence of contaminating positive control material. The development of readily distinguishable artificial positive control material offers distinct advantages to real-time PCR assays over using control material derived from clinical material.