**4.21 DNA aptamers**

Aptamers emerged as a good alternative to antibodies as affinity reagents. Recently, ssDNA aptamers that specifically bind with the recombinant VP2 (rVP2) protein of CPV-2 with affinity in the nanomolar range have been reported. The ssDNA aptamers specific to CPV-2 (rVP-2) were selected by the Systematic evolution of ligands through exponential enrichment (SELEX) method and their target binding was assessed by dot blot and enzyme-linked oligonucleotide assay (ELONA). Aptamers with high binding affinity and specificity against rVP-2 could be employed in diagnostics for rapid detection of CPV-2 [73].
