An Improved Multiplex IC-RT-PCR Assay Distinguishes Nine Strains of Potato virus Y.

A multiplex reverse-transcription polymerase chain reaction (RT-PCR) assay was previously developed to identify a group of Potato virus Y (PVY) isolates with unusual recombinant structures (e.g., PVY and SYR-III) and to differentiate them from other PVY strains. In the present study, the efficiency of this multiplex RT-PCR assay was validated and extended considerably to include five additional strains and strain groups not tested before. To make the multiplex RT-PCR assay more applicable and suitable for routine virus testing and typing, it was modified by replacing the conventional RNA extraction step with the immunocapture (IC) procedure. The results obtained using well-characterized reference isolates revealed, for the first time, that this multiplex RT-PCR assay is an accurate and robust method to identify and differentiate the nine PVY strains reported to date, including PVY (both PVY and PVY-O5), PVY, PVY, PVY, PVY, PVY, PVY-NE11, PVY, and PVY, which is not possible by any of the previously reported RT-PCR procedures. This would make the IC-RT-PCR procedure presented here a method of choice to identify PVY strains and assess the strain composition of PVY in a given area. The IC-RT-PCR protocol was successfully applied to typing PVY isolates in potato leaf tissue collected in the field.