Hepatitis B Virus

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Amjad Khan Afridi
Hepatitis B Virus
Contents
Generalconcept
Definitionsof hepatitis
HepatitisB virus
Whatis hepatitis
Reservoir
Causativeagentand its structure
Decoypartial
Symptoms,mode of transmission and RF
Replication
Epidemiology
Preventionsstatistics
Epidemiology Notes
Madam Saira

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Amjad Khan Afridi
General Concepts
Hepatitis = 'inflammation of the liver'.
six medically important viruses are commonly described as “hepatitis viruses”:
HAV,HBV,HCV,HDV,HEV,HGV.
Definitions for Hepatitis
 Acute: Short term and/or severe.
 Chronic: Lingering or lasting - may or may not be severe
 Fulminant: Developing quickly and lasting a short time, high mortality rate.
 Cirrhosis: Hardening: may be the result of infection or toxins (e.g. alcohol)
 Jaundice: Yellowing of the skin, eyes,etc due to raised levels of bilirubin in the blood due to
liver damage.
 Hepatocellular carcinoma： is closely associated with hepatitis B, and at least in some regions
of the world with hepatitis C virus.

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Amjad Khan Afridi
Hepatits B
What is Hepatits B?
Hepatitis B is serious disease caused by a virus that infect the liver.
Can cause lifelong infection, cirrhosis (liver scarring), liver cancer,liver failure and death Hepatitis B.
Reservoir ofhepatitis B virus
 Humansare the reservoir.
Causative agent and its structure
 Causative agent is Hep B virus
 Family: Hepadnaviridae
 Hepa: for liver
 Dna: for Deoxyribonucleic acid
 Virion (aka Dane particle):
 Outer lipid envelope
 Icosahedralnucleocapsid core composed of protein
 Outer envelope proteins:
 Binding & entry into susceptible cells
 Size: small, 42 nm in diameterStructure
HBV Structure

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Amjad Khan Afridi
Decoy particles
 HBsAg-containing particles are released into the serum of infected people and outnumber the
actual virions.
 Spherical or filamentous
 They are immunogenic and were processed into the first commercial vaccine against HBV.
GENOME

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Amjad Khan Afridi
HBV Replication
 Reverse transcription: one of the mRNAs is replicated with a reverse transcriptase making the
DNA that will eventually be the core of the progeny virion
 RNA intermediate: HBV replicates through an RNA intermediate and produces and release
antigenic decoy particles.
 Integration: Some DNA integrates into host genome causing carrier state .
Global Patterns of Chronic HBV Infection
 High (>8%): 45% of global population
 lifetime risk of infection >60%
 early childhood infections common
 Intermediate (2%-7%):43% of global population
 lifetime risk of infection 20%-60%
 infections occur in all age groups
 Low (<2%): 12% of global population
 lifetime risk of infection <20%
 most infections occur in adult risk groups

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Amjad Khan Afridi
Symptoms
 Nausea
 Loss of appetite
 Vomiting
 Fatigue
 Fever
 Dark urine
 Pale stool
 Jaundice
 Stomach pain
 Side pain
 A person may have all, some or none of these
HBV Modes of Transmission
 Parenteral- IV drug abusers, health workers are at increased risk.
 Sexual - sex workers and homosexuals are particular at risk.
 Perinatal(Vertical) - mother(HBeAg+) →infant.
High-risk groups for HBV infection
 Injection drug users
 Sex partners of those with Hep B
 Sex with more than one partner
 Men who have sex with men
 Living with someone with chronic Hep B
 Contact with blood
 Transfusions, travel, dialysis

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Amjad Khan Afridi
Pathogenesis & Immunity
 Virus enters hepatocytes via blood
 Immune response (cytotoxic T cell) to viral antigens expressed on hepatocyte cell surface
responsible for clinical syndrome
 5 % become chronic carriers (HBsAg> 6 months)
 Higher rate of hepatocellular ca in chronic carriers, especially those who are “e” antigen positive
 Hepatitis B surface antibody likely confers lifelong immunity (IgG anti-HBs)
 Hepatitis B e Ab indicates low transmissibility
Clinical Features

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Amjad Khan Afridi
Statistics on HBV:
 Most healthy adults (90%) who are infected will recover and develop protective antibodies
against future hepatitis B infections
 90% of infants and up to 50% of young children infected with hepatitis B will develop chronic
infections.
Hepatitis B In the World
 2 billion people have been infected (1 out of 3 people).
 400 million people are chronically infected.
 10-30 million will become infected each year.
 An estimated 1 million people die each year from hepatitis B and its complications.
 Approximately 2 people die each minute from hepatitis B.
Hepatitis B In the United States
 12 million Americans have been infected (1 out of 20 people).
 More than one million people are chronically infected .
 Up to 100,000 new people will become infected each year.
 5,000 people will die each year from hepatitis B and its complications.
 Approximately 1 health care worker dies each day from hepatitis B.
Hepatitis B in China
 1.3 billion people
 the world's largest population of hepatitis B patients, with nearly half a million people dieing of
the liver disease every year
 120 million Chinese have tested positive for hepatitis B, which has become a severe public health
problem in the country
Epidemiology
 350,000,000 carriers worldwide
 120,000,000 carriers in China
- the carrier rate can exceed 10%
- 15 to 25% of chronically infected patients will die from chronic liver disease
 500,000 deaths/year in China
 982,297 liver disease in China 2005
 50% of children born to mothers with chronic HBV in the US are Asian American

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Amjad Khan Afridi
Current Treatment Options
 Interferon alfa (Intron A) Response rate is 30 to 40%.
 Lamivudine (Epivir HBV) (relapse ,drug resistance)
 Adefovir dipivoxil (Hepsera)
Prevention
 Vaccination
- highlyeffectiverecombinantvaccines
 HepatitisBImmunoglobulin(HBIG)
- exposedwithin48hours of the incident/neonateswhose mothersare HBsAgand
HBeAgpositive.
 Othermeasures
- screeningof blooddonors,bloodandbodyfluidprecautions.
PreparedBy Amjad Khan Afridi
Date : 22 May, 2016