1. Introduction Treatment of hepatitis B virus (HBV) infection aims to: suppress HBV replication prevent progression of liver fibrosis prevent cirrhosis prevent hepatic decompensation reduce hepatocellular carcinoma (HCC) risk reduce liver-related mortality prevent mother-to-child transmission where indicated control HBV-related extrahepatic disease achieve durable immune control ideally achieve HBsAg loss, the closest currently available endpoint to a functional cure The cen

1. Introduction HBV drug resistance is the ability of hepatitis B virus (HBV) variants carrying specific genetic substitutions to replicate despite exposure to an antiviral drug at concentrations that would normally suppress susceptible virus. It is primarily a consequence of: the high replication rate of HBV the error-prone nature of the viral polymerase/reverse transcriptase selection pressure exerted by antiviral therapy inadequate suppression of viral replication Drug res

1. Introduction HBV viral load refers to the quantity of hepatitis B virus (HBV) DNA present in a patient's blood, usually measured in serum or plasma. It is one of the most important quantitative parameters in the evaluation and management of chronic hepatitis B. The standard method is: Quantitative nucleic acid amplification testing (NAAT), usually real-time PCR. HBV viral load is generally reported as: IU/mL — International Units per millilitre It provides a direct measure

1. Introduction Diagnosis of hepatitis B virus (HBV) infection requires integration of: Clinical findings HBV serology HBV DNA testing Liver biochemistry Assessment of hepatic fibrosis Imaging Risk assessment No single test answers every clinical question. The fundamental diagnostic markers are: HBsAg Indicates current HBV infection. Anti-HBc Indicates natural exposure to HBV. Anti-HBs Indicates immunity. HBeAg / anti-HBe Provide information about viral replication and immune

1. Introduction Hepatitis B virus (HBV) is a small, partially double-stranded DNA virus that replicates through an RNA intermediate using a viral reverse transcriptase. Although HBV is a DNA virus, its replication strategy makes it highly prone to genetic variation. The viral polymerase: lacks effective proofreading activity generates replication errors produces genetically diverse viral populations Therefore, HBV exists within an infected individual as a quasispecies rather

1. Definition The window period of hepatitis B virus (HBV) infection is the relatively short interval during the evolution of acute HBV infection when: HBsAg has disappeared, but anti-HBs has not yet become detectable, so conventional HBsAg and anti-HBs testing may both be negative. During this period, the most useful serological marker is: IgM anti-HBc Therefore, the classic window-period pattern is: HBsAg − / anti-HBs − / IgM anti-HBc + This is one of the most important ser

1. Definition The term HBV carrier state traditionally refers to a person who has persistent hepatitis B surface antigen (HBsAg) in the blood but has little or no active liver inflammation. Historically, such patients were called: "Inactive HBV carriers" or "inactive HBsAg carriers." However, the term carrier can be misleading because HBV infection remains biologically active at some level and can reactivate. Modern terminology therefore prefers: HBeAg-negative chronic HBV in

1. Definition Chronic hepatitis B virus (HBV) infection is persistent HBV infection characterized classically by HBsAg positivity for ≥6 months, with or without detectable HBV DNA, HBeAg, or clinical liver disease. Chronic HBV infection is not synonymous with chronic hepatitis. A person may have: Persistent HBsAg with minimal liver inflammation High HBV DNA with normal ALT Low HBV DNA with normal ALT Active chronic hepatitis with fluctuating ALT and HBV DNA Advanced fibrosis

Introduction Acute hepatitis B is a newly acquired infection with hepatitis B virus (HBV), characterized by a period of viral replication followed by an immune response that may result in clinical hepatitis and, in most immunocompetent adults, eventual viral clearance. The clinical spectrum is extremely broad: asymptomatic infection → mild hepatitis → symptomatic acute hepatitis → severe hepatitis → fulminant acute liver failure The most important determinant of outcome is th

Introduction Hepatitis B virus (HBV) serology is often considered difficult because multiple antigens, antibodies and molecular markers appear and disappear at different stages of infection. The key to interpretation is not to interpret one marker in isolation. Instead, interpret the complete pattern using: HBsAg anti-HBs total anti-HBc IgM anti-HBc HBeAg anti-HBe HBV DNA ALT clinical history previous vaccination/infection history duration of HBsAg positivity The central diag

Introduction Hepatitis B virus (HBV) infection produces a characteristic pattern of viral antigens, antibodies and nucleic-acid markers that change over the course of infection. Correct interpretation of these markers allows us to determine: Whether HBV infection is present Whether infection is acute or chronic Whether infection has resolved Whether the patient is immune because of vaccination Whether viral replication is occurring Whether a patient is in the HBeAg-positive o

Introduction Hepatitis B virus (HBV) infection produces a remarkably broad spectrum of disease—from asymptomatic infection and self-limited acute hepatitis to fulminant hepatitis, chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC). The most important principle in understanding HBV pathogenesis is: HBV is largely non-cytopathic; most hepatocellular injury is caused by the host immune response against HBV-infected hepatocytes rather than by direct viral destruction

Introduction Hepatitis B virus (HBV) has one of the most unusual replication strategies among human DNA viruses. HBV contains a small, approximately 3.2-kb partially double-stranded circular DNA genome, but unlike conventional DNA viruses, it replicates through an RNA intermediate and reverse transcription. The mature virion contains relaxed circular DNA (rcDNA), which enters the hepatocyte nucleus and is repaired to form covalently closed circular DNA (cccDNA). cccDNA then a

Introduction Hepatitis B virus (HBV) possesses one of the smallest known genomes among human DNA viruses, yet it encodes a highly sophisticated replication system. The HBV genome is approximately: 3.2 kb (≈3,200 nucleotides) It is: Circular Partially double-stranded Highly compact Rich in overlapping open reading frames (ORFs) Associated with a terminally protein-linked viral DNA strand Replicated through an RNA intermediate The mature viral genome inside the Dane particle is

Introduction Hepatitis B virus (HBV) is a small, enveloped, hepatotropic DNA virus belonging to the family Hepadnaviridae and genus Orthohepadnavirus. Despite having a genome of only approximately 3.2 kb, HBV has a highly organized structure and an exceptionally compact genetic architecture. Its structure is closely linked to its unique replication strategy, hepatocyte tropism, persistence, immune escape, and clinical manifestations. The infectious HBV virion is called the: D

Introduction Hepatitis B virus (HBV) is an enveloped, hepatotropic, partially double-stranded DNA virus belonging to the family Hepadnaviridae. HBV is one of the most important human viral pathogens because infection may produce: Acute hepatitis Fulminant hepatitis Chronic hepatitis An inactive infection state Cirrhosis Hepatic decompensation Hepatocellular carcinoma (HCC) Extrahepatic manifestations Unlike many other DNA viruses, HBV replicates through an RNA intermediate an