This is an ancillary to the NIDDK-sponsored Hepatitis B Research Network (HBRN) Study Cohort Study NCT01263587. This study will examine the balance between immune regulatory and effector responses in hepatitis B-infected participants enrolled in the HBRN study (NCT01263587).

Aim 1: The clinical and virological status of chronic Hepatitis B (HBV) infection is defined by distinct patterns of immune effector and regulatory responses: The investigators propose that one or more immune regulatory are induced during chronic hepatitis B that define the extent of immune tolerance vs. activation with associated disease activity and viremia. Towards this end, the immune effector and regulatory responses relative to serum HBV DNA, alanine aminotransferase (ALT), Hepatitis B e antigen (HBeAg), Hepatitis B surface antigen (HBsAg) and liver histology will be examined in a cross-sectional manner in patients with chronic HBV and control groups.

Aim 2: Clinical hepatitis flares during chronic hepatitis B reflect altered balance between immune regulatory and effector responses.

Inclusion Criteria:

• Providing informed consent for this ancillary study.

Exclusion Criteria:

• Children under 18 years of age, participants with anemia
• Hgb<10 or Hct<30, congestive heart failure or chronic lung disease requiring oxygen, active coronary artery disease with unstable angina, sepsis or renal failure, other significant medical conditions, autoimmune disease or immunosuppression.

The study population will be recruited from multi-site clinical centers in the United States and Canada including primary care hospitals and community centers that have enrolled into the HBRN cohort study (NCT01263587).