Objective      To screen ssDNA oligonucleotide aptamers targeting human cytomegalovirus (HCMV) PP65 antigen with high affinity and specificity.       Methods      The systematic evolution of ligands by exponential enrichment (SELEX) method was used for screening specific aptamers targeting HCMV PP65 antigen. The affinity of the aptamers was detected by ELISA and their secondary structures were predicted by the DNAMAN software. Then

the sequence with the highest affinity to PP65 was used as the capture aptamer to establish a sandwich assay based on magnetic bead-aptamer-antigen-fluorescence labeled monoclonal antibodies for detecting PP65 antigen.       Results      A total of 6 aptamers with high affinity and specificity to PP65 molecule were obtained by 8 cycles of SELEX.       Conclusion      A good foundation for developing aptamer-based HCMV PP65 antigen detection method has been established.