BACKGROUNDTo study the antibody against hepatitis C virus first envelope (HCV-E1) protein in the sera from patients with HCV and to evaluate the application of HCV-E1 antigen in detection of HCV antibody.

METHODSPurified E1 engineering protein was used as antigen to develop an ELISA for detecting E1 antibody in 80 national reference sera, 821 blood donors' sera and l20 sera from clinical patients with hepatitis.

RESULTSAnti-HCV E1 was positive in 70% (28/40) and negative in 100% (40/40) of 80 national reference sera, and 1.9% (16/821) was positive in blood of the sera donors' and 68% (492/720) positive in sera of patients with hepatitis. Most anti-HCV E1 positive sera were positive for core, NS 3 and NS 5A, but only a few sera were positive for E1 antigen. Of the sera from 218 clinical patients, 813 blood donors and 848 normal people that were anti-HCV negative tested by commercial anti HCV ELISA kit, 1.4%, 1.1% and 0.9% were anti-HCV E1 positive, respectively. Investigation of seroconversion on three patients showed that anti-E1 was first detectable.

CONCLUSIONSDetection of anti-HCV E1 by engineered E1 protein is sensitive and specific. The prevalence and early presence of E1 antibody in HCV infected patients reflect the active status of the disease to a certain extent. Detection of the antibody is useful in clinical diagnosis.