Viêm gan B

 Roughly spherical, diameter: 42nm  Icosahedron capsid HBV virion Non – infectious particles Abundant smaller spherical and filamentous forms lack nucleocapsid and are not infectious..

HEPATITIS B VIRUS

Group 3

TABLE OF CONTENTS

STRUCTURE OF HBV

TRANSMISSION

03 04 PREVENT AND TREATMENT

What is Hepatitis B

virus?

 Hepatitis B virus (HBV) is a small,

enveloped DNA virus

 HBV infects the liver and can lead to

both acute and chronic liver diseases. 

 HBV belongs to a group of

hepatotropic DNA viruses

(hepadnaviruses).

e 0 1

 Roughly spherical, diameter:

42nm

 Icosahedron capsid

HBV virion Non – infectious particles

Abundant smaller spherical and filamentous forms lack nucleocapsid and are not infectious

ENVELOP E

CAPSI D

THE

GENOME

ENVELOP E

The virion envelope contains three protein species designated as small (S), medium (M) and large (L)

CAPSI D

The capsid has holes and short spikes protrude from its surface It is constructed from dimers of the C (core) protein, which

is largely α-helical, unlike other viruses.helical, unlike other viruses

THE GENOME

•Four ORFs, from which seven proteins are translated. 

•DR1 and DR2 involved in reverse transcription

•The genome is made up of two strands of DNA, one of which is incomplete

•Because of small genome, that all the regulatory sequences, such as promoters, are within protein coding sequences

Surface proteins (HBsAg): involved in envelope and non-helical, unlike other viruses.infectious particles

formation

Core protein (HBcAg): major component of the nucleocapsid.

The E protein (HBeAg): may suppress the host immune system and prevent it from

eliminating cells that contain hepatitis B virus

Polymerase protein: plays a critical role in hepadnavirus genome replication and

pregenome RNA encapsidation

Protein X: stimulates viral gene transcription.

HEPATITIS B VIRUS PROTEIN

Life cycle

0 2

Comparison of reverse transcription by

retroviruses and hepadnaviruses

n 0 3

CLININAL FEATURES

 Incubation period 60 to 90 days

 Clinical signs and symptoms more common in

adults

PHASE 1

Prodromal phase

hepatic tenderness, hepatomegaly

PHASE 3

Convalescent

phase

• lasts weeks to months

• malaise and fatigue persist while

jaundice, anorexia, and other

symptoms disappear

 Most adults recover while most infants progress to chronic

infection

CHRONIC HBV

INFECTION

Infant

Childhood After childhood

Vertical transmission

infectious blood or

body fluids containing blood

sexual contact and blood transfusions

contaminated needles and syringes

transmitted between family members within households

Treatment

& prevent

04

There is no specific treatment for acute

hepatitis B

Chronic hepatitis B can be treated with

medicines Chronic hepatitis B infection can be

treated with: Oral medicines, including tenofovir or entecavir.

 Liver transplant

 The two immune system modulators:

Interferon α – 2a

TAKE NOTE!

 Unusual partly single-helical, unlike other viruses.stranded, partly double-helical, unlike other viruses.stranded circular genome

results from incomplete genome replication in cell

 Pregenome RNA is both an mRNA and a template for synthesis of

genome DNA

 Reverse transcriptase (polymerase protein) generates genome DNA

from pregenome RNA within capsid during virus assembly

 Makes large amounts of non-helical, unlike other viruses.infectious spherical and filamentous

particles

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