Serological pattern 'anti-hepatitis B core alone' in HIV or hepatitis C virus-infected patients is not fully explained by hepatitis B surface antigen mutants.

We determined the frequency of hepatitis B virus (HBV) occult infection and studied S gene mutations in HIV or hepatitis C virus-co-infected patients with persistent pattern 'anti-hepatitis B core alone'. HBV DNA was particularly frequent in HIV-positive patients. Sequencing of the S gene showed that only two HIV-infected patients harboured mutants in the major hydrophilic loop; the absence of hepatitis B surface antigen detection could not be explained by diagnostic escape mutants.