Improved detection of grapevine leafroll-associated virus 1 by magnetic capture hybridisation RT-PCR on a conserved region of viral RNA

Summary. We report the development of a sensitive diagnostic method for the detection of the grapevine leafroll-associated virus 1 (GLRaV-1). We have considered the current shortcoming in detection of GLRaV-1 to be linked to two factors, sequence variation in the viral RNA and low template concentration. Sequence information available allowed the selection of optimal target sequences for detection by RT-PCR, having high copy number and low levels of sequence variation. This was combined with the use of magnetic capture hybridisation to allow the removal of RT-PCR inhibitors and the addition of 100-fold excess template RNA to a single RT-PCR. The reproducibility of the technique was confirmed using field samples.