Morphology of Hepatitis B virus | HBV

Описание: Hepatitis B virus is a small, enveloped DNA virus belonging to the family Hepadnaviridae. It shows pleomorphic forms in blood.

1. Size and Shape

The complete infectious particle is called the Dane particle

It is spherical and measures about 42 nm in diameter.

2. Structure of Dane Particle

The Dane particle has two main components:

A. Outer Envelope

Made of lipid bilayer derived from host cell membrane

Contains Hepatitis B surface antigen (HBsAg)

Envelope helps in attachment and entry into hepatocytes.

B. Inner Core (Nucleocapsid)

Icosahedral core of about 27 nm

Composed of Hepatitis B core antigen (HBcAg)

Inside core contains:

Partially double-stranded circular DNA

DNA polymerase enzyme (reverse transcriptase activity)

3. Viral Antigens

HBV contains three important antigens:

HBsAg – surface antigen (envelope)

HBcAg – core antigen (nucleocapsid)

HBeAg – secreted antigen (marker of high infectivity)

4. Pleomorphic Particles in Blood

In infected serum, HBV is seen in three forms:

Dane particles (42 nm) – complete infectious virus

Spherical particles (22 nm) – excess HBsAg, non-infectious

Filamentous/tubular forms (22 nm diameter) – non-infectious, made of HBsAg

These extra particles are produced in large amounts and help the virus evade immune response.