Localization of hepatitis B surface antigen epitopes present on variants and specifically recognised by anti‐hepatitis B surface antigen monoclonal antibodies

Abstract

Small hepatitis B surface antigen (HBsAg) is considered to be the best marker for the diagnosis of Hepatitis B virus infection. However, HBsAg variants with mutations within the "a" determinant may be poorly or not detected by diagnostic assays. Three anti-HBsAg monoclonal antibodies (6H6B6, 27E7F10, and 2G2G10), directed against conformational epitopes, were tested for their ability to detect the wild-type HBsAg as well as variant forms and their respective epitopes were localised on the HBsAg sequence by using the phage-displayed peptide library technology. Whereas 6H6B6 did not detect mutations T123N, S143L, D144A and G145R, 27E7F10 binding was affected by mutations P120T and G145R. In contrast, 2G2G10 reacted strongly with all tested variants including variant with the G145R mutation. Part of the 6H6B6 epitope was located in the major hydrophilic region (MHR) at residues 101-105, the 27E7F10 epitope (residues 214-219) was located near the C-terminal end of the antigen and the 2G2G10 epitope at residues 199-208, within the theoretical fourth transmembrane helix. The 2G2G10 epitope localisation brings information about the HBsAg structure and the validity of established topological models. Finally, 2G2G10 is a valuable tool for HBsAg variant detection that is used as capture phase in a new bioMérieux diagnostic assay, which is currently in development.

Modification of Asparagine-Linked Glycan Density for the Design of Hepatitis B Virus Virus-Like Particles with Enhanced Immunogenicity

“…The HBsAgS multiplex panel consists of 19 monoclonal antibodies (MAbs) directed against the N terminus, the external hydrophilic loop region, and C-terminal domain epitopes spanning amino acid residues 99 to 226 of HBsAgS. MAbs 1, 2, 3, and 4 (6H6B6, 27E7F10, F4-7B, and 2G2G10, respectively) were kindly provided by Béa-trice Seignères, bioMérieux (50,51), MAbs 18 and 19 were from XTL Biopharmaceuticals (52), MAbs 5, 6, 7, 8, and 9 (RFHBS 1, 2, 4, 7, and 18, respectively) were kind gifts from Howard Thomas, Imperial College London (53), and MAbs 10-17 were kindly provided by Thomas Leary, Abbott Diagnostics (54). The epitopes are categorized into the following domains: N terminal (MAb 1), loop 1 (MAbs 5, 6, and 10), loop 2 (MAbs 7, 8, 11, 12, 16, 17, and 19), loop 1/2 combinational (MAbs 13, 14, and 15), C terminal (MAbs 2, 3, and 4), and conformational (MAbs 9 and 18).…”

Unusual Naturally Occurring Humoral and Cellular Mutated Epitopes of Hepatitis B Virus in a Chronically Infected Argentine Patient with Anti-HBs Antibodies

“…Moreover, some of the recorded HBs antigen variants may influence the accuracy of the results obtained with currently used diagnostic tests, as reported with previously studied mutants (9,12,13,19,20,30,37), since some of them may prove undetectable, although others may not result in a complete loss of antigenicity (17).…”

An Overview of Hepatitis B Virus Surface Antigen Mutant in the Asia Pacific

“…Single or multiple mutations occurring within the Major Hydrophilic Region (MHR) could lead to a conformational change of this epitope which can affect the antigenicity (Ma and Wang, 2012). Several notable mutations: T/I126S, Q129H, G130N, S143L, D144A, G145A, and G145R (Figure 2), are involved in diagnostic failure, and escape from being neutralised by antibodies induced by available vaccines as well as resulting in a failure of HBIg therapy (Jolivet-Reynaud et al, 2001). On the other hand, mutations outside the ''a'' determinant region are located primarily at positions 120 and 123.…”

“…On the other hand, mutations outside the ''a'' determinant region are located primarily at positions 120 and 123. The Pro at position 120 can mutate to Gly/Thr/Ser/Asn/Gln (Jolivet-Reynaud et al, 2001), and mutation at position 123 gives rise to T123N, which is responsible for both diagnostic and HBIg therapeutic failure (Ly et al, 2006).…”

“…Between 500,000 and 1 million new HCC cases are diagnosed annually, with an age-adjusted annual rate of 14.9 per 100,000 in men, and 5.5 per 100,000 in women (Gomaa et al, 2008;Jolivet-Reynaud et al, 2001). In the highly endemic Asia-Pacific region, HBV infection accounts for 17% of HCC cases in Japan (Lemon et al, 2000), but is associated with up to 80-90% of HCC cases in Singapore and Vietnam (Pokorski and Ohlmer, 2001).…”