Molecular Virology and Life Cycle
The hepatitis B virus is a prevalent human infection with no cure at present. It is a significant cause of global morbidity and mortality and has achieved its persistence in humans via its complex life cycle and ability to use its few protein products in
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		    Molecular Virology and Life Cycle Darren J. Wong and Stephen A. Locarnini
 
 Abstract
 
 The hepatitis B virus is a prevalent human infection with no cure at present. It is a significant cause of global morbidity and mortality and has achieved its persistence in humans via its complex life cycle and ability to use its few protein products in a multifunctional manner to subvert and evade immune detection and clearance. These aspects of the virus are discussed in detail, as are the development of clinically important mutations in the viral genome that develop as a result of host immune selection, as well as those selected by the introduction of antiviral therapy or vaccination. Keywords
 
 Hepatitis B • Molecular Virology • Lifecycle • Antiviral Resistance
 
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 Classification
 
 The hepatitis B virus (HBV) is the most well-known member of the virus family  Hepadnaviridae. The species in this family are split amongst two genera— Avihepadnavirus and Orthohepadnavirus—with human HBV belonging to the latter. HBV has been further classified into ten genotypes, A to J, which are based D.J. Wong Department of Gastroenterology, St. Vincent’s Hospital, Melbourne, Fitzroy, VIC 3065, Australia e-mail: [email protected] S.A. Locarnini (*) Department of Molecular Research and Development, Victorian Infectious Diseases Reference Laboratory, Melbourne, VIC 3000, Australia e-mail: [email protected] © Springer Nature Singapore Pte Ltd. 2018 J.-H. Kao, D.-S. Chen (eds.), Hepatitis B Virus and Liver Disease, https://doi.org/10.1007/978-981-10-4843-2_1
 
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 D.J. Wong and S.A. Locarnini
 
 on whole-genome nucleotide diversity of at least 8% (Norder et al. 1994; Stuyver et  al. 2000; Kann and Gerlich 2005; Tatematsu et  al. 2009; Olinger et  al. 2008). There is distinct geographical variation amongst these genotypes (Table 1.1). Table 1.1  Overview of the ten genotypes of HBV. Adapted from Locarnini et al. (2013). Note that genotype J has yet to be verified, as only one case has been isolated Genome length (nt) 3221
 
 Frequency of mutationa PC BCP Uncommon Common
 
 3215
 
 Common
 
 Uncommon
 
 3215
 
 Common
 
 Common
 
 3182
 
 Common
 
 Common
 
 3212
 
 NK
 
 NK
 
 3215
 
 Uncommon
 
 NK
 
 G
 
 3248
 
 Very common
 
 NK
 
 H
 
 3215
 
 NK
 
 NK
 
 I J
 
 3215 3182
 
 – –
 
 – –
 
 Genotype A
 
 Subtype A1 A2
 
 B
 
 B1 B2 B3 B4 C1 C2 C3 C4
 
 C
 
 D
 
 C5 D1 D2 D3 D4
 
 E F
 
 F1 F2 F3 F4
 
 Global distribution Africa, Asia Northern Europe, North America Japan Rest of Asia Indonesia, China Vietnam, Cambodia Far East Far East Polynesia Australian indigenous population Philippines Europe, Middle East, Egypt, India, Asia Europe, Japan Europe, Asia, South Africa, USA Australia, Japan, Papua New Guinea Sub-Saharan Africa, UK, France Central and South America, Bolivia Brazil, Venezuela, Nicaragua Venezuela, Panama, Columbia Argentina, Bolivia, France USA, Germany, Japan, France USA, Japan, Nicaragua Vietnam, Cambodia Japan
 
 Modified from Locarnini et al. (2013) a PC, precore mutations such as G1896A; BCP, basal core promoter mutations such as A1762T, G1764A; very common (most isolates); common (up to		
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