Hepatitis B causes
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Hepatitis B |
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Hepatitis B causes On the Web |
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American Roentgen Ray Society Images of Hepatitis B causes |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor In Chief: Cafer Zorkun, M.D., Ph.D. [2]
Cause
Structure of Virus
Virions consist of an outer lipid envelope and an icosahedral nucleocapsid core composed of protein. The nucleocapsid encloses the viral DNA and a DNA polymerase that has reverse transcriptase activity. The outer envelope contains embedded proteins which are involved in viral binding of, and release into, susceptible cells. Virion shape is generally spherical with a diameter of 40 - 48 nanometers (nm), but pleomorphic forms exist, including filamentous and spherical bodies lacking a core. These "subviral" particles are not infectious.
The DNA genome is not segmented but rather partially double-stranded, containing a long and short segment which overlap approximately 240 nucleotides to form an open circle. The longer strand is 3020-3320 nucleotides long, and the shorter is 1700-2800 nucleotides long.[1] The virus can be divided into four major serotypes (adr, adw, ayr, ayw) based on antigenic epitopes present on its envelope proteins, and into eight genotypes (A-H) according to overall nucleotide sequence variation of the genome. Different genotypes have distinct geographic distributions. For example, genotypes B and C are prevalent in China and neighboring countries.
References
- ↑ Hepadnaviridae characteristics - ICTVdB