The correlation between hepatitis C core antigen and HCV RNA levels with respect to HIV status, HCV genotype and IFNL4 polymorphism

BACKGROUND: Serum HCV core antigen (HCVcAg) concentrations correlate with HCV RNA levels in HCV monoinfected patients. Data in HCV/HIV co-infected patients are still limited. We aim to compare the use of HCVcAg measurement with respect to HIV status, HCV genotypes, interferon lambda-4 (IFNL4) polymorphism and clinical parameters. MATERIALS AND METHODS: We analyzed an untreated cohort of 104 patients with HCV mono-infection and 85 patients with HCV/HIV co-infection. Serum HCVcAg was measured by a commercial chemiluminescent microparticle immunoassay. The presence of IFNL4 polymorphism ss469415590 was identified by real time PCR. RESULTS: Log HCVcAg levels were significantly correlated with corresponding log HCV RNA levels (r = 0.889, p < 0.001), but not correlated with ALT levels and liver stiffness. The correlation between HCV RNA and HCVcAg was particularly high in co-infected patients and those with high viremia. Mean log HCVcAg concentration was significantly higher in co-infected patients than in monoinfected patients. Patients harboring TT/TT genotype of ss469415590 had significantly higher levels of log HCVcAg than those with non-TT/TT genotype. HCVcAg levels were similar across HCV genotypes. CONCLUSION: HCVcAg concentrations had an excellent correlation with HCV RNA levels, particularly in HCV/HIV co-infected individuals and might be associated with IFNL4 polymorphism. HCVcAg testing could be used as an alternative to HCV RNA assays in resource-limited settings.