This study has the aim of describing viral mutation profiles in patients diagnosed with chronic hepatitis B receiving antihepadnaviral therapy.

This is a naturalistic cross-sectional study of chronic hepatitis B subjects receiving nucleoside or nucleotide antihepadnaviral therapy.

It is anticipated approximately 800 subjects will be recruited at 20 Australian sites. Data will be collected on the study subjects and analyses performed to describe factors contributing to the emergence of viral mutations in Australian patients with chronic hepatitis B.

Inclusion Criteria:

• Aged 18 years and over
• Provided informed consent
• Diagnosis of chronic hepatitis B (HBsAg documented for at least 6 months)
• Currently prescribed antihepadnaviral therapy (including, but not limited to: lamivudine, adefovir, entecavir, tenofovir or telbivudine) for chronic hepatitis B management
• Been taking current antihepadnaviral therapy for at least 6 months prior to recruitment
• Negative tests for HIV Ab, Hepatitis C Ab and Hepatitis D Ab within the previous 2 years

Exclusion Criteria:

• Known or suspected co-infection with HIV, Hepatitis C or Hepatitis D
• Concomitant immunosuppression / immunomodulatory therapies
• Diagnosis of hepatocellular carcinoma where anticipated life expectancy is less than 6 months
• Current participation in an interventional, blinded, pharmaceutical industry-sponsored clinical trial
• Current Child Pugh class C classification (current Child Pugh score > 9)
• Other known or suspected cause of chronic liver disease
• Any other reason that, in the investigator's opinion, participation in the study would not be in the participant's best interest.

Subjects with a diagnosis of chronic hepatitis B who have been prescribed antihepadnaviral therapy for at least 6 months.