Full length NS5A gene of the hepatitis C virus was amplified by PCR using plasmid pBAC25 containing HCV nonstructural gene as template. The amplified fragment (about 1.34 kb) was cloned into plasmid pQE32, and the recombinant plasmid pQENS5A was expressed in JM109 strain. The NS5A protein was purified by NiSO 4 metal chelating resin, and characterized by Western blot. Its antigenecity was determined by ELISA. The positive detection rate of anti NS5A was 75% (69/92) in ninety two clinic sera. The positive rate of anti NS5A was 82.5% (33/40) in fourty positive standand sera, and the negative rate of anti NS5A was 100% (40/40) in fourty negative standand sera. The results showed that the Full length NS5A proteinn had the higher sensitivity and specificity in the detection of HCV antibody in sera, we suggested that NS5A protein was a useful antigen for blood screening.
