SIGNIFICANCE OF ANTI-E2 IN THE DIAGNOSIS OF HCV INFECTION IN PATIENTSON MAINTENANCE HEMODIALYSIS - ANTI-E2 IS FREQUENTLY DETECTED AMONG ANTI-HCV ANTIBODY-NEGATIVE PATIENTS

A routine screening test used in the diagnosis of hepatitis C virus (H CV) infection is the anti-HCV antibody (anti-HCV) test containing core , NS3, NS4, and NS5 antigens of HCV. When HCV infection occurs in immu nocompromised hosts, antibody formation against core, NS3, or NS4 anti gens may be weak in the presence of HCV viremia and cannot be detected by routine anti-HCV tests. This study proposed that in immunocompromi sed hosts such as patients with chronic renal failure (whose capacity to form antibodies is diminished), antibody formation against the E2 r egion would be preserved, because the E2/NS1 region of HCV is strongly immunogenic. The aim of this study is to evaluate the significance of anti-E2 in the diagnosis of HCV infection among patients on maintenan ce hemodialysis who are anti-HCV-negative, using a conventional third- generation enzyme immunoassay (EIA) kit. The E2/NS1 gene of HCV encodi ng the amino acid sequence 388-664 was molecularly cloned into a vecto r containing an SV 40 promotor and was expressed in Chinese Hamster ov ary cells. Using this E2 protein, the anti-E2 test was performed by EI A on 100 patients on maintenance hemodialysis, and on 50 patients with chronic hepatitis C who were anti-HCV-positive, to evaluate the antig enecity of the E2 protein. Of the 100 hemodialysis patients, 15 (15.0% ) tested anti-HCV-positive using a third generation anti-HCV ELISA kit . Of the 85 patients who tested negative for anti-HCV, nine (10.6%) we re anti-E2-positive and six (66.7%) of these anti-E2 positive patients showed HCV RNA viremia by HCV reverse transcription-polymerase chain reaction. Fourty-two (84.0%) of 50 patients with chronic hepatitis C w ere anti-E2-positive. As a control group, we tested for anti-E2 among 30 blood donors who were anti-HCV-negative, and also among 85 patients with hepatocellular carcinoma who were anti-HCV-negative, but in both groups, none (0%) was anti-E2-positive. In conclusion, these data sug gest that the E2 protein of HCV should be included in a diagnostic ant i-HCV kit for the detection of HCV infection in immunocompromised pati ents.