aptamers as accurate and sensitive tools for the diagnostic of viral diseases

Viral infections can cause serious diseases for humans and animals. accurate and sensitive detection of viruses is often crucial for clinical diagnosis and therapy. aptamers are single strand dna or rna molecules that are artificially synthesized by an in vitro technology known as the systematic evolution of ligands by exponential enrichment (selex). similar to antibodies, aptamers bind specifically to their targets, including proteins, carbohydrates, and simple chemical molecules. however, compared with antibody, aptamers are easy to synthesize and modify and can bind to a broad range of targets. thus, aptamers are promising for detecting viruses and treating viral infections. with these advantages in mind, many studies on aptamer-based viral diagnosis and treatments are currently in progress. this study was done to select dna aptamers that can specifically bind to the infectious hematopoietic necrosis virus (ihnv) nucleoprotein (ihnv-np), which is considered as the main target antigen for ihnv detection. also to better detection of ihnv-np, different nanoparticles (aunps, cnt, cnt-aunps) used in order to signal enhancement. to begin this effort, the recombinant virus nucleoprotein was expressed in e. coli host system following optimization of soluble protein expression. the soluble protein obtained by the optimized condition was efficiently purified in high yield and successfully detected by monoclonal antibodies in sandwich elisa and western blotting methods. selection of high-affinity aptamers to the target protein in selex was monitored using enzyme linked oligonucleotide assay (elona) and real-time pcr. between five groups of aptamers were identified, three aptamers sequences with higher binding capacity for ihnv-np were further characterized to determine their binding affinity, specificity and structural stability. the selected aptamers exhibited the dissociation constants blew 100 nm, no cross-reactivity was observed between aptamers and non-specific targets, retained their binding ability over a broad range of temperatures and showed high structural stability following freezing and de-freezing. for signal enhancement in elona test, cnt-aunps showed the best signal compared to two nanoparticles. the results of this experiment showed that combined with nanotechnology, aptamer technology represents an integrated platform providing a sensitive and highly specific tool for viral detection.