[Establishment of a new combined enzyme immunoassay for detection of HBV preS1 and core antigens and the consistency with HBV DNA test].
In this study, a new combined enzyme immunoassay(NRAg ELISA) for detection of HBV PreS1 and core antigens which was highly consistent with serum HBV DNA test was established. The serial serum dilution test indicated that the average sensitivity of the assay was 10(3.2) genome copies/mL (95% CI: 10(2.2-4.2) genome copies/mL), which was notably higher than the test performed on Pre S1 or core antigen alone. The test with sera from 994 blood donors whose HBsAg were negative demonstrated that the specificity of this assay was 99.7% (95% CI: 99.1%-99.9%). 271 serum samples from chronic hepatitis patients were also examined and the result showed that the total consistent rate between NRAg ELISA and HBV DNA was 96.3% (95% CI: 93.3%-98.2%). The NRAg ELISA S/CO(signal/cutoff) was closely correlated with HBV genome copies (R = 0.9158, n=231). Furthermore,by using this assay,we found a patient whose HBsAg was negative but HBV DNA was positive. Sequencing result showed that HBV genome from this patient had a point mutation in the "a"epitope of S gene. Our results indicate that HBV NRAg ELISA has a high relativity with HBV DNA test, and can effectively detect the mutation of HBsAg,it is expected to be a potent tool for screening HBsAg mutant and is a convenient method for substituting HBV DNA test.