Selection and versatile application of virus-specific aptamers

Although the significance of molecular diagnostics in routine plant virus detection is rapidly growing, the preferred methods are still antibody-based enzyme immunoassays. In the past decade, aptamers have been demonstrated to be viable alternatives of antibodies in many applications. We set out to select apple stem pitting virus (ASPV)-specific aptamers and to apply them as antibody substitutes in various immunoassay methods. The applied systematic evolution of ligands by exponential enrichment (SELEX) procedure resulted in highly discriminative aptamers selectively binding to the target virus coat protein even in complex protein matrixes. We developed protocols for exploitation of aptamers in diverse plant virus diagnosis methods, such as dot and Western blot analyses and enzyme-linked oligonucleotide assay (ELONA). Our selected aptamers proved to be superior to the available antibody in all aspects. In contrast to the antibody, the aptamers decorate both native and denaturated proteins, and ELONA produces higher signal intensity than traditional enzyme-linked immunosorbent assay (ELISA) with virus-infected plant extract. Summarily, our results present the selection and practical utilization of first plant virus-specific aptamers. Most important, the first application of ELONA for virus detection is demonstrated, which proposes a novel, more flexible, and cost-effective means of virus diagnostics.