Ana Avello´n* and Jose´ M. EchevarriaHepatitis Laboratory, Diagnostic Microbiology Service, National Centre of Microbiology,Instituto de Salud Carlos III, Majadahonda, Madrid, SpainThe prevalence in the population of hepatitisB virus (HBV) surface antigen (HBsAg) variantsthat may impair diagnosis, or allow the virus toescape vaccine-induced immunity or passiveimmunoglobulin therapy is unknown. A genomefragment encoding HBsAg amino acids 112–212was ampliﬁed and sequenced from the sera of272 unselected DNA-positive, HBV-chronic car-riers from Spain. The genotype and the HBsAgsubtype were predicted from the sequences.Analysis of amino-acid positions 112–157revealed single or multiple substitutions in 39%of the carriers studied. Mutations were notdetected for residues 121, 135, 137, 139, 140,141, 142, 146, 147, 148, 149, 151, 152, 153, 155,156, and 157. Substitutions reported previouslyto be in association with failures of diagnostictests or with vaccine or immunoglobulin therapyescape were found in 12.5%, 6.6%, and 9.2%of carriers, respectively. Met133Thr (2.2%);Gln129His, Met133Ile, Phe/Tyr134Asn (1.8%);Phe/Tyr134Leu,Gly145Ala(1.5%),andPro120Thr(1.1%) were the most frequent. Other substitu-tions, including Gly145Arg (0.4%), were found ata frequency of less than 1%. Samples containingHBV mutants were tested with three commercialassays for HBsAg screening. Almost all themutants reacted to the upper cut-off values ofthe assays, but six samples with weak reactivitywithoneormoreofthemethodswerealsofound.Thus, HBV mutants with a potential impact onclinical and public health issues are moderatelyfrequent among chronic carriers from Spain,although their inﬂuence on the performance ofdiagnostic tests seems to be slight. J. Med.Virol. 78:24–36, 2006.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/jmv.20516

Frequency of hepatitis B virus 'a' determinant variants in unselected Spanish chronic carriers.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-0691.2008.02053.x

Molecular epidemiology of hepatitis B virus in Iran

Hepatitis B virus (HBV) can be classified into nine immunological subtypes or eight genotypes The most prevalent genotypes in Asia are genotypes B and C HBV is transmitted parenteraly and can produce either asymptomatic or symptomatic disease Although the consequences of acute hepatitis B can be severe, serious sequelae are associated with chronic infections HBV seroprevalence ranges from intermediate (2%-7%) to high (≥8%) levels in Asia Several strategies for the control and prevention of HBV infection have been found to be efficacious They include vaccination and the administration of HBIG, interferon-a and nucleoside/nucleotide analogues However, these procedures also apply selective pressures on HBV in infected individuals leading to the generation and accumulation of mutations in the S gene Most of these mutations occur in the major hydrophilic region (MHR) of the S gene These mutations create public health concerns as they can be responsible for reactivation of hepatitis B and occult hepatitis B infection The inability to detect occult infections means that these individuals may become blood donors This suggests that new strategies for donor evaluation and selection may need to be developed to protect the blood supply

Hepatitis B virus S gene escape mutants.

Prevalence of HBsAg mutants and impact of hepatitis B infant immunisation in four Pacific Island countries.

We report and characterize a novel mutant of the hepatitis B virus surface antigen (HBsAg). The mutant was isolated from a symptomatic patient who was found to be persistently positive for both HBsAg and anti-hepatitis B surface antibody (anti-HBs) and a long-lasting anti-HBc (core) IgM. Due to the unusual immune serological profile, polymerase chain reaction and sequencing were performed and revealed a genotype D mutant HBV (LBN). Aligned with known HBsAg sequences from GenBank, the LBN variant matched to consensus subtype ayw2 and revealed five mutation positions. Interestingly, none of the mutations was found within the group-specific "a" determinant region (124-147) and, specifically, two of the five mutations, T118K and P120Q, were located only a few amino acids adjacent to the 124-147 region. Using a panel of six monoclonal antibodies and vaccine raised human neutralizing antibodies, the recombinant wild-type HBsAg and the novel variant LBN HBsAg were investigated for their immunological reactivity. Vaccine raised human anti-HBs showed less reactivity to the variant LBN HBsAg than to wild-type HBsAg in enzyme immune assays. Furthermore, our observations demonstrate the influence of adjacent residues on the group-specific "a" determinant structural configuration; this resulted in severe antigenic changes of the immunodominant region as well as in the subtype serology. The importance of the variant LBN lies in the observation that mutations close to the "a" determinant can change the immunodominant region structure and therefore alter the group specific determinant antigenicity even though no mutations are present within this region. Hence, the classical definition of the "a" determinant cluster may need to be extended to cover a broader region to include the requirement of adjacent amino acids to support its conformation. In conclusion, by understanding the HBsAg major immunodominant region structure and by using a combination of antibodies with specificity covering all key mutation locations, maximal anti-HBs-based protection, and highly sensitive diagnostic assays can be achieved.

Characterization of a novel hepatitis B virus mutant: demonstration of mutation-induced hepatitis B virus surface antigen group specific "a" determinant conformation change and its application in diagnostic assays.

Perinatal transmission of and infection with hepatitis B (HBV) in early childhood are observed in a small proportion of the offspring of hepatitis B surface antigen (HBsAg)-positive mothers who are vaccinated against HBV immediately after giving birth. The children may be infected by wild-type HBV or by variants with amino acid substitutions in the "a" determinant of HBsAg, particularly at position 145 and, rarely, at positions 120, 126, 129, 131, 141, and 144. Four hundred and forty-six newborn infants of HBsAg-positive mothers in the northeastern part of the Czech Republic received combined active and passive immunisation against HBV. Only one child became an HBsAg carrier. This followed a mild, acute HBV illness in the beginning of the second year of his life. HBV DNA encoding the "a" determinant and surrounding region of HBsAg was sequenced after amplification from the plasma of the child and his mother. The child was infected with variants of HBsAg with substitutions at residues 137 and 139. The virus of the mother had changes at residues 120 and 121. HBV from both child and mother had an unusual substitution at residue 118 and seemed to be of the ayw subdeterminant. J. Med. Virol. 67:11-14, 2000. (C) 2000 Wiley-Liss, Inc.

Unusual hepatitis B surface antigen variation in a child immunised against hepatitis B.

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Unusual hepatitis B surface antigen variation in a child immunised against hepatitis B.