Frequency of isolated hepatitis B core antibody in HIV-hepatitis C virus co-infected individuals.

Association between isolated hepatitis B core antibody (anti-HBc) and hepatitis C virus (HCV) infection has been noted in HIV-infected individuals. This study describes the frequency of isolated anti-HBc and its possible value for the detection of HBV-DNA in HIV-infected patients with or without HCV co-infection. Ninety-two HIV-infected patients were enrolled in the study. Hepatitis B surface antigen (HBs Ag), anti-HBs, anti-HBc, anti-HCV, HIV viral load and CD4 count were tested in all subjects. Then we compared 63 subjects with HIV-HCV co-infection with 29 subjects with HIV infection alone regarding isolated anti-HBc (HBs Ag negative, anti-HBs negative and anti-HBc positive). The presence of HBV-DNA was determined by real-time polymerase chain reaction in serum samples of patients with isolated anti-HBc. Of 63 anti-HCV-positive patients, 18 subjects (28.6%, 95% [confidence interval] CI: 22.6-34.6%), and of 29 anti-HCV-negative patients, five subjects (17.2%, 95% CI: 11.5-22.9%) had isolated anti-HBc. HBV-DNA was detectable in three of 18 anti-HCV-positive patients (16.7%, 95% CI: 9.7-23.7%) and none of the anti-HCV-negative patients with isolated anti-HBc. Our study showed that individuals co-infected with HIV and HCV were more likely to have isolated anti-HBc than subjects with HIV alone. This investigation also demonstrates that the presence of isolated anti-HBc in HIV-HCV-infected individuals may reflect occult HBV infection in these patients.