Diagnostic utility of hepatitis C virus core antigen in hemodialysis patients.

BACKGROUND: Patients undergoing hemodialysis are at high risk for Hepatitis C virus infection. Anti-HCV antibody detection is widely used for screening this infection but is not sensitive for window period detection. An ELISA to detect the HCV Core Antigen has recently become available.

OBJECTIVES: To investigate the utility of the HCV core Antigen ELISA in the detection of HCV infection in hemodialysis patients and to compare with 3rd generation ELISA validated by real-time PCR.

METHODS: Two hundred fifty hemodialysis patients were included in the study. Anti-HCV antibodies and Total HCVcAg was determined by third generation ELISA kits. HCV RNA was determined using Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) and sensitivity of the two assays was confirmed by estimating viral load using real-time PCR.

RESULTS: Forty-three out of 250 (17.2%) patients were positive for anti-HCV antibodies and HCVcAg. 13/250 (5.2%) were positive for HCVcAg but anti-HCV negative, which is statistically significant (P<0.05). All 13 were confirmed viremic by in-house nested RT-PCR leading to specificity of 100%. Viral load of 49,258+/-28,682 copies/mL were detected in HCVcAg positive cases in comparison to 239,383+/-107,805 copies/mL in the only anti-HCV positive group (P<0.001). False negative cases for HCVcAg assay accounted for 2/250 (0.8%) in which the viral load was 306+/-461 copies/mL which was significantly lower in comparison to HCVcAg positive group (P<0.001, t-test=9.982).

CONCLUSIONS: Total HCVcAg ELISA is an accurate serological marker for early identification of HCV infection, than is possible by currently used serological assay. It will be useful for patients undergoing hemodialysis who have a longer window period due to immunosuppressed state. It is both a cost-effective and a less labor-intensive alternative to PCR, enhancing its clinical utility.