Inclusion Criteria:

• Documented chronic hepatitis B infection (> 6 months) with detectable HBV DNA > 5x100000 copies/ml (PCR-Assay) on two separate occasions
• HBe-Ag positive, anti-HBe negative
• HBs-Ag positive, anti-HBs negative
• a liver biopsy within the last 12 months prior to screening consistent with chronic hepatitis B
• Documented HIV-infection
• CD4-cell count > 200 cells/µl
• Elevated serum ALT > ULN but £ 10X ULN as determined by two abnormal values taken >14 days apart during the six months before the first dose of study drug with at least one of the determinations obtained during the screening period
• Serum-creatinine clearance > 70 ml/min, according to Cockcroft-Gault
• Anorganic phosphate > 0,65 mmol/l (2,0 mg/dl)
• Neutrophils above 1.5 G/l, Hb above 11.5 g/dl (females) or 12.5 g/dl(males), thrombocytes above 90 G/l
• Ability to understand and sign a written consent form

Exclusion Criteria:

• Older than 65 years of age, younger than 18 years of age
• Pregnancy, lactating women
• Concomitant / prior medication / hypersensitivity to study medication
• Prior use of antiretroviral therapy in particular adefovir dipivoxil, tenofovir DF, lamivudine, emtricitabine, or interferon
• Treatment with interleukin 2 or corticosteroids less than 6 months prior to the first dose of study drug or the expectation that such treatment will be needed at any time during the study.
• Currently receiving investigational agents unless approved by the study coordinator
• History of having received any systemic anti-neoplastic (including radiation < 6 months prior to the first dose of study drug or the expectation that such treatment will be needed at any time during the study.
• Patients not receiving HAART (Arm A) must be expected not be in need for antiretroviral therapy for HIV-infection at any time during the study 72 weeks, as judged by the investigator.
• Hypersensitivity to any of the components of the study drugs (tenofovir, emtricitabine, pegylated interferon alfa-2a)

Concurrent liver disease:

• Ongoing hepatitis A, C or Delta infection: positive testing for anti HAV-IgM, HCV-RNA, anti-HDV, HDV-Ag
• Ongoing EBV or CMV infection: positive testing for anti EBV-IgM, CMV-eAg
• Autoimmune hepatitis
• Patients with a value of alpha-fetoprotein >100 ng/mL are excluded, unless stability (less than 10% increase) has been documented over at least the previous 3 months and magnetic resonance tomography of the liver shows no evidence of hepatocellular carcinoma.
• Liver cirrhosis, CHILD-Pugh Score B or C; history or other evidence of bleeding from esophageal varices or other conditions consistent with decompensated liver disease
• History or other evidence of a medical condition associated with chronic liver disease other than HBV (e.g., hemochromatosis, autoimmune hepatitis, metabolic liver diseases including Wilson's and alpha1-antitrypsin deficiency, alcoholic liver disease, toxin exposures, thalassemia).
• Alcohol abuse (> 30g ethanol/d for males, > 20 g ethanol/d for females) or use of other recreational drug substances)
• Serum total bilirubin above twice the upper limit of normal
• ALT > 10 times the upper limit of normal

Neurological / psychiatric disorders:

• History of severe psychiatric conditions(ICD F30 - 33), graded by the consulting psychiatrist, in particular severe depression. Severe psychiatric disease is defined as major depression or psychosis, a period of treatment with an antidepressant medication or tranquilizer at therapeutic doses for depression or psychosis for at least 3 months, a suicidal attempt, hospitalization for psychiatric disease, or a period of disability due to a psychiatric disease.
• History of a severe seizure disorder or current anticonvulsant use.

Cardiovascular disorders:

• History or other evidence of chronic pulmonary disease associated with functional limitation.
• Severe cardiac disease (e.g., NYHA Functional Class III or IV, myocardial infarction within 6 months, ventricular tachyarrhythmias requiring ongoing treatment, unstable angina or other significant cardiovascular diseases).

Immunological disorders:

• Elevated auto-antibody findings
• History of immunologically mediated disease (e.g. inflammatory bowel disease, idiopathic thrombocytopenic purpura, lupus erythematosus, autoimmune hemolytic anemia, scleroderma, severe psoriasis, rheumatoid arthritis).
• Thyroid disease with thyroid function poorly controlled on prescribed medications. Patients with elevated thyroid stimulating hormone or T4 concentrations, with elevation of antibodies to thyroid peroxidase and any clinical manifestations of thyroid disease are excluded.

Other:

• Gastrointestinal malabsorption
• Evidence of an active or suspected cancer or a history of malignancy where the risk of recurrence is ³20% within 2 years. Patients with a lesion suspicious of hepatic malignancy on a screening imaging study will only be eligible if the likelihood of carcinoma is £10% following an appropriate evaluation.
• History of organ transplantation
• History or other evidence of severe retinopathy (e.g. CMV retinitis, macula degeneration) or clinically relevant ophthalmological disorder due to diabetes mellitus or hypertension