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 obtained
   prior 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 with
   any nucleoside or nucleotide analogue) OR treatment-experienced participants (defined
   as 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 at
   least 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 hepatitis
   D virus.

   - Evidence of hepatocellular carcinoma .

   - Any history of, or current evidence of, clinical hepatic decompensation.

   - Abnormal hematological and biochemical parameters, including aspartate
   aminotransferase (AST) > 10 x ULN.

   - Received solid organ or bone marrow transplant.

   - History of malignancy within the past 5 years, with the exception of specific cancers
   that are cured by surgical resection; individuals under evaluation for possible
   malignancy are not eligible.

   - Currently receiving therapy with immunomodulators (eg, corticosteroids),
   investigational agents, nephrotoxic agents, or agents capable of modifying renal
   excretion.

   - Individuals receiving ongoing therapy with drugs not to be used with tenofovir
   alafenamide or tenofovir disoproxil fumarate or individuals with a known
   hypersensitivity to study drugs, metabolites, or formulation excipients.

   - Current alcohol or substance abuse judged by the investigator to potentially interfere
   with participant compliance.

   - Any other clinical condition or prior therapy that, in the opinion of the
   Investigator, would make the participant unsuitable for the study or unable to comply
   with dosing requirements.

Note: Other protocol defined Inclusion/Exclusion criteria may apply.