Subtypes of Australia antigen and hepatitis-B virus

Bouvier, George L. Le

doi:10.1001/jama.222.8.928

Cited by 45 publications

(10 citation statements)

References 15 publications

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“…Mutations affecting the antigenic characteristics of the virus have given rise to four major serotypes ( adw, adr, ayw, ayr ) (Le Bouvier et al, 1972, Norder et al, 1992a). Part of the S protein is the immunological “a” determinant, which is conserved in all the serotypes and is the target of vaccine-elicited antibodies.…”

Section: Hbv Serotypes and Genotypesmentioning

confidence: 99%

Antiviral therapies: Focus on hepatitis B reverse transcriptase

Michailidis

Kirby

Hachiya

et al. 2012

The International Journal of Biochemistry & Cell Biology

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Hepatitis B virus (HBV) is the etiologic agent of mankind’s most serious liver disease. While the availability of a vaccine has reduced the number of new HBV infections, the vaccine does not benefit the approximately 350 million people already chronically infected by the virus. Most of the drugs approved by the FDA for the treatment of hepatitis B target the reverse transcriptase (RT or P gene product) and are nucleoside RT inhibitors (NRTIs) that suppress viral replication. However, prolonged monotherapies directed against a single target result in the emergence of viral resistance. HBV genotypic differences affect NRTI resistance, and because the reading frames of the S (surface antigen) and P genes partially overlap, genomic differences that affect the surface of the virus may also alter the viral polymerase sequence, function and drug susceptibility. The scope of this review is to assess the effects of HBV genotypic variation on the development of drug resistance to NRTIs. Some RT residues that vary among different genotypes are in the vicinity of residues that mutate and give rise to NRTI resistance. Interactions between these amino acids can help explain the effect of HBV genotype on the development of NRTI resistance during antiviral therapies, and might help in the design of improved therapeutic strategies.

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Section: Hbv Serotypes and Genotypesmentioning

confidence: 99%

Antiviral therapies: Focus on hepatitis B reverse transcriptase

Michailidis

Kirby

Hachiya

et al. 2012

The International Journal of Biochemistry & Cell Biology

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“…T raditionally, hepatitis B virus (HBV) is classified into 4 subtypes or serotypes (adr, adw, ayr, and ayw) based on antigenic determinants of the hepatitis B surface antigen. 1 These subtypes can be further classified into 9 serotypes (ayw1, ayw2, ayw3, ayw4, ayr, adw2, adw4, adrqϩ, and adrqϪ). 2 Epidemiologic studies found that the prevalence of these serotypes varies in different parts of the world.…”

mentioning

confidence: 99%

Clinical significance of hepatitis B virus genotypes

2002

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See Article in HEPATOLOGY 2002;35:922-929 T raditionally, hepatitis B virus (HBV) is classified into 4 subtypes or serotypes (adr, adw, ayr, and ayw) based on antigenic determinants of the hepatitis B surface antigen. 1 These subtypes can be further classified into 9 serotypes (ayw1, ayw2, ayw3, ayw4, ayr, adw2, adw4, adrqϩ, and adrqϪ). 2 Epidemiologic studies found that the prevalence of these serotypes varies in different parts of the world. In addition, antibody to the common determinant, "a," confers protection against all serotypes. To date, there has been very little data on the clinical significance of HBV serotypes.Advances in molecular biology techniques revealed significant diversities in sequences of HBV isolates, accounting for the allelic differences among the 4 major HBV serotypes. Based on an intergroup divergence of 8% or more in the complete nucleotide sequence, HBV can be classified into 7 genotypes A-G. [3][4][5] However, genotyping can be accomplished based on a partial sequence of the HBV genome such as the pre-S or S gene. Several methods have been used for HBV genotyping including direct sequencing, restriction fragment length polymorphism, line probe assay, and enzyme-linked immunoassay.Contrary to hepatitis C virus genotyping, HBV genotyping is a research tool that is only beginning to gain popularity among researchers in hepatitis B. Whether HBV genotyping will constitute part of the clinical evaluation of hepatitis B patients depends on the availability of simple and inexpensive tests and the relevance of the information gained. Currently, restriction fragment length polymorphism is the most commonly used method for HBV genotyping. A line probe assay similar to that used for hepatitis C virus genotyping is also available. These assays can be easily applied in clinical diagnostic laboratories. The key issue is, does knowledge of the HBV genotype help in patient management? The specific questions include, (1) Is there a correlation between HBV genotype and HBV replication, activity of liver disease, clinical outcome, and treatment response? (2) What is the predominant HBV genotype in each country? Is the geographical distribution of HBV genotypes related to the endemicity of HBV infection? (3) Is there a correlation between HBV genotype and risk of progression to chronic infection? (4) Does infection with one HBV genotype confer protection against infection with other HBV genotypes?Answers to some of the questions raised are beginning to emerge but many of the answers are based on a few studies in selected patient populations. Current information on the geographical distribution of HBV genotypes is summarized in Table 1. However, existing information is incomplete. As an example, earlier studies suggested that HBV genotype A is predominant in the United States. A recent study indicated that HBV genotype G is also prevalent because it was present in 11 of 82 patients from the state of Georgia. 5 However, in an ongoing study involving 17 liver centers across the United States, we found...

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“…The subtypes of HBsAg, which are geographically distributed, all contain the 'a' determinant and are defined using appropriate antisera (mAbs are also available). There are two pairs of mutually exclusive subtype determinants, d and y [15] and w and r [16]. There are nine subtypes (because there are subsubtypic determinants), but four (adw, ayw, adr, ayr), are the major ones.…”

Section: The Surface Gene Of Hbv and Subtypesmentioning

confidence: 99%

Mechanism of emergence of hepatitis B virus escape variants: approaches to prevention

1998

Journal of Viral Hepatitis

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Subtypes of Australia antigen and hepatitis-B virus

Cited by 45 publications

References 15 publications

Antiviral therapies: Focus on hepatitis B reverse transcriptase

Antiviral therapies: Focus on hepatitis B reverse transcriptase

Clinical significance of hepatitis B virus genotypes

Mechanism of emergence of hepatitis B virus escape variants: approaches to prevention

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