Abstract: Objective To compare the colloidal gold method with nucleic acid test （NAT） using ELISA positive HCV samples so as to observe the practical significance of the three methods in the safety ensurance of clinical blood transfusion. Methods The samples of blood donors were found to be positive for HCV by two ELISA methods and the results were analyzed by means of NAT and colloidal gold method. Results The NAT positive rate was 37% in 45 cases of anti- HCV positive sera,and the rate of colloid gold test was 77.8%%. No NAT positive samples were found in those with average value of S/CO below 10.0 when examined by two ELISA reagents whereas the frequencies of positive NAT was 70.8% and 62.9% in those with the average value of S/CO over 10.0.The Colloidal gold method revealed the positive rates of 46.1% and 40% respectively in those whith the value of S/CO between 1.0 and 5.0. The positive rates of colloidal gold method reached 75% in the samples of S/CO values between 5.0 and 10.0 and 95.8% in those of S/CO over 10.0. Conclusion The positive rates of NAT and Colloidal gold method are elevated with increase of S/CO value tested by ELISAs. The NAT is irreplaceable for conventional ELISAs but combination of ELISAs with NAT might improve the detection of HCV RNAs.

Key words: Positive anti-HCV, Nucleic acid test, Colloidal gold test, Correlation study