A Study of ARC-521 Injection in Normal Adult Volunteers and Patients With Chronic Hepatitis B (CHB)

0.9% normal saline

Approximately two hours prior to ARC-521 or placebo administration, participants will be pre-treated with an oral antihistamine, selected by the investigator from the list of approved antihistamines that is available in that country. Approved antihistamines are: diphenhydramine 50 mg by mouth (PO), chlorpheniramine 8 mg PO, or hydroxyzine 50 mg PO.

Approximately two hours prior to ARC-521 or placebo administration, participants will be pre-treated with acetaminophen (500 - 1000 mg PO, per local strength availability).

Participants take entecavir OR tenofovir daily throughout the study.

Participants take entecavir OR tenofovir daily throughout the study.