This non-interventional clinical study will be conducted to prospectively collect serial plasma samples from subjects with chronic HBV infection who are initiating antiviral therapy. These samples will be used to estimate clinical utility endpoints for the Aptima HBV Quant assay, which is used as an aid in the management of HBV-infected patients undergoing HBV antiviral therapy.

Inclusion Criteria:

• The subject is chronically infected with HBV.The subject is treatment naïve and is initiating HBV antiviral therapy with either entecavir or tenofovir as indicated in the FDA approved label
• The subject will be considered treatment naïve if he/she had <12 weeks of oral antiviral therapy with any nucleoside or nucleotide therapy
• The subject is at least 18 years of age at the time of enrollment
• Adequate medical records are available for collection of protocol-defined demographics, baseline patient characteristics, medical history, virology and specific laboratory results, and other information to verify enrollment criteria
• The subject and/or legally authorized representative is willing and able to provide consent prior to providing a specimen(s)

Exclusion Criteria:

• Subject is in one of the following patient populations:

  • Acute HBV infection
  • Patients who are HBV immune tolerant
  • Human immunodeficiency virus (HIV) and/or hepatitis C virus (HCV) co-infection
  • Solid organ or bone marrow transplant recipients
  • Renal failure or dialysis
  • Evidence or history of hepatic decompensation
  • Evidence or history of hepatocellular carcinoma

• Underlying liver disease other than HBV

• Receiving chemotherapy, immunosuppressive agents

• Subject is unsuitable for study participation based on the Investigator's decision (eg, unlikely to comply with study visit schedule, significant medical complication)

• Participating in another investigational study that the Investigator believes might interfere with the subject's participation in this study

Treatment naïve men and women ≥18 years of age with chronic HBV infection initiating entecavir or tenofovir treatment.