Study to Compare Tenofovir Alafenamide (TAF) Versus Tenofovir Disoproxil Fumarate (TDF) in Participants With Chronic Hepatitis B Infection Who Are Positive for Hepatitis B e Antigen

Key Inclusion Criteria:

• Ability to understand and sign a written informed consent form, which must be obtainedprior to initiation of study procedures.
• Adult males and non-pregnant, non-lactating females.
• Documented evidence of chronic HBV infection.
• HBeAg-positive, chronic hepatitis B with all of the following:
• HBeAg-positive at screening.
• Screening HBV DNA ≥ 2 x 10^4 IU/mL
• Screening serum alanine aminotransferase (ALT) level > 60 U/L (males) or > 38 U/L (females) and ≤ 10 x the upper limit of the normal range (ULN).
• Treatment-naive participants (defined as < 12 weeks of oral antiviral treatment withany nucleoside or nucleotide analogue) OR treatment-experienced participants (definedas participants meeting all entry criteria [including HBV DNA and serum ALT criteria]and with ≥ 12 weeks of previous treatment with any nucleoside or nucleotide analogue).
• Previous treatment with interferon (pegylated or non-pegylated) must have ended atleast 6 months prior to the baseline visit.
• Adequate renal function.
• Normal electrocardiogram (ECG).

Key Exclusion Criteria:

• Females who are breastfeeding.
• Males and females of reproductive potential who are unwilling to use an "effective",protocol specified method(s) of contraception during the study.
• Co-infection with hepatitis C virus, human immunodeficiency virus (HIV), or hepatitisD virus.
• Evidence of hepatocellular carcinoma .
• Any history of, or current evidence of, clinical hepatic decompensation.
• Abnormal hematological and biochemical parameters, including aspartateaminotransferase (AST) > 10 x ULN.
• Received solid organ or bone marrow transplant.
• History of malignancy within the past 5 years, with the exception of specific cancersthat are cured by surgical resection; individuals under evaluation for possiblemalignancy are not eligible.
• Currently receiving therapy with immunomodulators (eg, corticosteroids),investigational agents, nephrotoxic agents, or agents capable of modifying renalexcretion.
• Individuals receiving ongoing therapy with drugs not to be used with tenofoviralafenamide or tenofovir disoproxil fumarate or individuals with a knownhypersensitivity to study drugs, metabolites, or formulation excipients.
• Current alcohol or substance abuse judged by the investigator to potentially interferewith participant compliance.
• Any other clinical condition or prior therapy that, in the opinion of theInvestigator, would make the participant unsuitable for the study or unable to complywith dosing requirements. Note: Other protocol defined Inclusion/Exclusion criteria may apply.