Serology
All people with HIV infection should be screened for HBV infection. Hepatitis B surface antigen (HBsAg) is the classic marker indicative of chronic infection. Although the detection of HBsAg is usually sufficiently sensitive to establish the presence of chronic HBV infection in the normal host, individuals may occasionally be negative for HBsAg, but still have active HBV replication, a phenomenon known as occult infection.4 It is recommended that all people with HIV infection should be tested with a panel of three serological tests to identify their serostatus: HBsAg, antibodies to HBV core antigen (anti-HBc) and antibodies to HBV surface antigen (anti-HBs). Patients found to be HBsAg positive should also have their e-antigen (HBeAg) status evaluated. People who are HBeAg positive usually have active replication, but some people who are negative for HBeAg and positive for anti-HBe may also have active replication and active liver disease. The failure to synthesise HBeAg is due to the presence of mutations in the precore or core promoter regions. All people who are negative for all markers should be offered vaccination.
HBV DNA
If a person is HBsAg positive or has isolated anti-HBc (without HBsAg or anti-HBs) as their only marker of infection, he or she should be evaluated for active HBV replication using a sensitive assay for HBV DNA (also known as HBV viral load). The level of HBV DNA determines whether patients are at risk for transmission, progressive disease, liver cancer and immune reconstitution flares of hepatitis. HBV DNA should ideally be quantified by nucleic acid amplification assays, usually sensitive real time polymerase chain reaction (PCR).
In chronic HBV infection, robust evidence indicates that the HBV DNA level is strongly associated with the development of the two major clinical complications; cirrhosis and hepatocellular carcinoma.5,6