In addition to playing roles of antibody surrogates in diagnostics, aptamers, a unique classof nucleic acid ligands, also exhibit great niches in therapeutics through exerting regulatory function on the target molecule. However, the ordinary in vitro selection method SELEX does not guarantee obtaining a �functional� aptamer for therapeutics. Here, we present a specially designed approach called epitope-specific SELEX (ES-SELEX) for direct screening functional aptamers and use this approach to obtain the aptamers capable of blocking recombinant influenza (A/New Caledonia/20/99) hemagglutinin (HA)'s function. The ES-SELEX starts with five rounds of ordinary (protein-specific) SELEX against the entire HA and then follows four additional rounds of epitope-specific selection, in which antagnoistic aptamers are evolved through fetuin competition on the sialic acid receptor-binding epitope of HA (Fig. 1(a)). After the selection process, we choose five aptamer candidates based on the structural stability and find four of them showing complete or partial antagonistic functionality against HA (Fig. 1(b)). A further study shows that aptamer 536 can inhibit HA function at a low picomole dose (6.25 pmol). The above results demonstrate that the concept of ES-SELEX is promising for directscreening functional aptamers for therapeutics.Figure 1 (a) ES-SELEX against the sialic acid receptor-binding epitope of HA. (b) Hemagglutination inhibition assay with the selected aptamers.

Direct screening of functional aptamers capable of influenza hemagglutination inhibition by epitope-specific SELEX

246th National Meeting (2013)

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