An ELISA for RNA helicase activity: application as an assay of the NS3 helicase of hepatitis C virus. 
A convenient enzyme-linked immunosorbent assay (ELISA) for RNA helicase activity was developed with principles similar to the standard assay.  The helicase ELISA utilizes a non-radioactive double-stranded substrate with a biotin-labeled template (long) strand hybridized to a digoxigenin (DIG)-labeled release (short) strand.  The template strand binds to the wells of streptavidin-coated microtiter plates (SA-MTP) where the helicase catalyzes the unwinding reaction.  Substrate not unwound retains the DIG-labeled release strand and is detected using anti-DIG coupled to horseradish peroxidase.  Chromogenic detection follows.  Absorbance measurement allows determination of unwinding efficiency of reactions.  To demonstrate effectiveness, the ELISA-based assay was used to study the unwinding activity of the hepatitis C virus (HCV) NS3 helicase.  Using a known inhibitor of NS3 helicase activity and two mutant HCV helicases, the ability of the assay to screen potential anti-helicase drugs and putative helicases is illustrated.  The helicase ELISA is more convenient than the standard helicase assay and is especially suited for the testing of large numbers of samples.