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TEM micrograph showing Hepatitis B virus virions
TEM micrograph showing Hepatitis B virus virions
Virus classification e
(unranked): Virus
Realm: Riboviria
Kingdom: Pararnavirae
Phylum: Artverviricota
Class: Revtraviricetes
Order: Blubervirales
Family: Hepadnaviridae
Genus: Orthohepadnavirus

See text

Orthohepadnavirus is a genus of viruses, in the family Hepadnaviridae.[1] Humans and other mammals serve as natural hosts. There are 12 species in this genus.[1] Diseases associated with this genus include: hepatitis, hepatocellular carcinoma (chronic infections), and cirrhosis.[1][2]


The genus contains the following species:[3]


Viruses in the genus Orthohepadnavirus are enveloped, with spherical geometries, and T=4 symmetry. The diameter is around 42 nm. Genomes are circular, around 3.2kb in length. The genome codes for 7 proteins.[1][2]

Genus Structure Symmetry Capsid Genomic arrangement Genomic segmentation
Orthohepadnavirus Icosahedral T=4 Non-enveloped Circular Monopartite

Life cycle

HBV replication

Viral replication is nucleo-cytoplasmic. Replication follows the dsDNA(RT) replication model. DNA-templated transcription, specifically dsDNA(RT) transcription, with some alternative splicing mechanism is the method of transcription.[1][2]

Translation takes place by leaky scanning. The virus exits the host cell by budding, and nuclear pore export. Human and mammals serve as the natural host. Transmission routes are sexual, blood, and contact.[1][2]

Genus Host details Tissue tropism Entry details Release details Replication site Assembly site Transmission
Orthohepadnavirus Humans; mammals Hepatocytes Cell receptor endocytosis Budding Nucleus Cytoplasm Vertical: parental; sex; blood


  1. 1.0 1.1 1.2 1.3 1.4 1.5 "ICTV Report Hepadnaviridae". Archived from the original on 8 February 2021. Retrieved 13 February 2023.
  2. 2.0 2.1 2.2 2.3 "Viral Zone". ExPASy. Archived from the original on 18 June 2015. Retrieved 15 June 2015.
  3. "Virus Taxonomy: 2020 Release". International Committee on Taxonomy of Viruses (ICTV). March 2021. Archived from the original on 20 March 2020. Retrieved 21 May 2021.

External links