Objective: To study antigenicity of HCV NS5 protein and dynamic changes of anti-NS5 in post-transfusion hepatitis C (PT-HC).
Methods: Epitopes of HCV NS5 protein were analyzed by Goldkey Program. NS5 gene fragment was amplified by reverse transcription and polymerize chain reaction (RT-PCR) from sera of PT-HC patients. Sequence analysis was performed, and recombinant strain was constructed. Series sera from PT-HC were detected for anti-NS5, ALT and HCV RNA.
Results: The homology of nucleotide and amino acid with genotype II in the same region was 91.8% and 92.4%, respectively. SDS-PAGE analysis showed an expressing band around 50 kD, the fusion protein represented about 21.4% of total bacterial protein. Western blot result proved the expressing band could specifically react with sera from hepatitis C patients. Detection results of series blood samples from PT-HC showed that the antibody against NS5 appeared relatively late, the positive conversion time was 182.9 +/- 168.5 day. Dynamic changes of anti-NS5 were correlated with serum ALT in most cases. The types of dynamic change of anti-NS5 were passing positive; intermittent positive; persistent positive, and persistent negative in two years.
Conclusion: Antibody against NS5 may reflect the disease activity to some extent. It appears relatively late, and is of no value in early stage diagnosis.