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Anderson M, Mangogola T, Phinius BB, Mpebe G, Aimakhu CO, Choga WT, Phakedi B, Bhebhe LN, Ditshwanelo D, Baruti K, Mpofu-Dobo L, Othusitse L, Ratsoma T, Gaolathe T, Makhema J, Shapiro R, Lockman S, Moyo S, Gaseitsiwe S. Hepatitis B Virus Prevalence among HIV-Uninfected People Living in Rural and Peri-Urban Areas in Botswana. Microorganisms 2024; 12:1207. [PMID: 38930589 PMCID: PMC11205512 DOI: 10.3390/microorganisms12061207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 06/10/2024] [Accepted: 06/12/2024] [Indexed: 06/28/2024] Open
Abstract
(1) Background: we determined the prevalence of the hepatitis B virus (HBV) amongst people without human immunodeficiency virus (HIV) in rural and peri-urban areas in Botswana. (2) Methods: We screened for the hepatitis B surface antigen (HBsAg) from archived plasma samples of people without HIV (n = 2135) randomly selected from the Botswana Combination Prevention Program (BCPP) (2013-2018). We sequenced 415 bp of the surface region using BigDye sequencing chemistry. (3) Results: The median age of participants was 31 (IQR: 24-46) and 64% (1360/2135) were female. HBV prevalence was 4.0% (86/2135) [95% CI: 3.3-4.9]) and ranged between 0-9.2%. Older participants (>35 years) had increased odds of HBV positivity (OR: 1.94; 95% CI: [1.32-2.86]; p = 0.001). Thirteen samples were sequenced and seven (53.8%) were genotype A, three (23.1%) were genotype D and genotype E each. Clinically significant mutations were identified in the surface region, but no classic drug resistance mutations were identified. (4) Conclusions: We report an HBV prevalence of 4.0% (95% CI 3.3-4.9) among people without HIV in rural and peri-urban communities in Botswana with varying rates in different communities. A comprehensive national HBV program is required in Botswana to guide HBV prevention, testing and management.
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Affiliation(s)
- Motswedi Anderson
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Africa Health Research Institute, Durban 4013, South Africa
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Thabo Mangogola
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Pan-African University (Life and Earth Sciences Institute), University of Ibadan, Ibadan 200132, Nigeria;
| | - Bonolo B. Phinius
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- School of Allied Health Professions, Faculty of Health Sciences, University of Botswana, Private Bag UB 0022, Gaborone, Botswana
| | - Gorata Mpebe
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Department of Biological Sciences, Faculty of Science, University of Botswana, Private Bag UB 0022, Gaborone, Botswana
| | - Christopher O. Aimakhu
- Pan-African University (Life and Earth Sciences Institute), University of Ibadan, Ibadan 200132, Nigeria;
| | - Wonderful T. Choga
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- School of Allied Health Professions, Faculty of Health Sciences, University of Botswana, Private Bag UB 0022, Gaborone, Botswana
| | - Basetsana Phakedi
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
| | - Lynnette N. Bhebhe
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
| | - Doreen Ditshwanelo
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
| | - Kabo Baruti
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Department of Biological Sciences, Faculty of Science, University of Botswana, Private Bag UB 0022, Gaborone, Botswana
| | - Linda Mpofu-Dobo
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Department of Biological Sciences and Biotechnology, Faculty of Sciences, Botswana International University of Science and Technology, Private Bag 16, Palapye, Botswana
| | - Lebogang Othusitse
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
| | - Tsholofelo Ratsoma
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Department of Biological Sciences, Faculty of Science, University of Botswana, Private Bag UB 0022, Gaborone, Botswana
| | - Tendani Gaolathe
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Faculty of Medicine, University of Botswana, Private Bag UB 0022, Gaborone, Botswana
| | - Joseph Makhema
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Roger Shapiro
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Shahin Lockman
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
- Division of Infectious Diseases, Brigham and Women’s Hospital, Boston, MA 02115, USA
| | - Sikhulile Moyo
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
- Division of Medical Virology, Faculty of Medicine and Health Sciences, University of Stellenbosch, Stellenbosch, Private Bag X1, Matieland 7602, South Africa
- School of Health Systems and Public Health, University of Pretoria, Private Bag X20, Pretoria 0028, South Africa
| | - Simani Gaseitsiwe
- Botswana Harvard Health Partnership, Private Bag BO320, Gaborone, Botswana; (M.A.); (T.M.); (B.B.P.); (G.M.); (W.T.C.); (B.P.); (L.N.B.); (D.D.); (K.B.); (L.M.-D.); (L.O.); (T.R.); (T.G.); (J.M.); (R.S.); (S.L.); (S.M.)
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
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Expression Level of Small Envelope Protein in Addition to Sequence Divergence inside Its Major Hydrophilic Region Contributes to More Efficient Surface Antigen Secretion by Hepatitis B Virus Subgenotype D2 than Subgenotype A2. Viruses 2020; 12:v12090967. [PMID: 32882910 PMCID: PMC7552069 DOI: 10.3390/v12090967] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 08/28/2020] [Accepted: 08/30/2020] [Indexed: 02/08/2023] Open
Abstract
Hepatitis B surface antigen (HBsAg) promotes persistent hepatitis B virus (HBV) infection. It primarily corresponds to small (S) envelope protein secreted as subviral particles. We previously found that genotype D clones expressed less S protein than genotype A clones but showed higher extracellular/intracellular ratio of HBsAg suggesting more efficient secretion. The current study aimed to characterize the underlying mechanism(s) by comparing a subgenotype A2 clone (geno5.4) with a subgenotype D2 clone (geno1.2). Five types of full-length or subgenomic constructs were transfected to Huh7 cells at different dosage. HBsAg was quantified by enzyme linked immunosorbent assay while envelope proteins were detected by Western blot. We found that ratio of extracellular/intracellular HBsAg decreased at increasing amounts of DNA transfected. Conflicting findings from two types of subgenomic construct confirmed stronger secretion inhibitory effect of the genotype D-derived large envelope protein. Chimeric constructs followed by site-directed mutagenesis revealed geno1.2 specific V118/T127 and F161/A168 in the S protein as promoting and inhibitory of HBsAg secretion, respectively. In conclusion, more efficient HBsAg secretion by subgenotype D2 than subgenotype A2 is attributed to lower level of S protein expression in addition to V118 and T127 in S protein, although its F161 and A168 sequences rather reduce HBsAg secretion.
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Wang Q, Michailidis E, Yu Y, Wang Z, Hurley AM, Oren DA, Mayer CT, Gazumyan A, Liu Z, Zhou Y, Schoofs T, Yao KH, Nieke JP, Wu J, Jiang Q, Zou C, Kabbani M, Quirk C, Oliveira T, Chhosphel K, Zhang Q, Schneider WM, Jahan C, Ying T, Horowitz J, Caskey M, Jankovic M, Robbiani DF, Wen Y, de Jong YP, Rice CM, Nussenzweig MC. A Combination of Human Broadly Neutralizing Antibodies against Hepatitis B Virus HBsAg with Distinct Epitopes Suppresses Escape Mutations. Cell Host Microbe 2020; 28:335-349.e6. [PMID: 32504577 DOI: 10.1016/j.chom.2020.05.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Revised: 03/09/2020] [Accepted: 05/08/2020] [Indexed: 02/08/2023]
Abstract
Although there is no effective cure for chronic hepatitis B virus (HBV) infection, antibodies are protective and correlate with recovery from infection. To examine the human antibody response to HBV, we screened 124 vaccinated and 20 infected, spontaneously recovered individuals. The selected individuals produced shared clones of broadly neutralizing antibodies (bNAbs) that targeted 3 non-overlapping epitopes on the HBV S antigen (HBsAg). Single bNAbs protected humanized mice against infection but selected for resistance mutations in mice with prior established infection. In contrast, infection was controlled by a combination of bNAbs targeting non-overlapping epitopes with complementary sensitivity to mutations that commonly emerge during human infection. The co-crystal structure of one of the bNAbs with an HBsAg peptide epitope revealed a stabilized hairpin loop. This structure, which contains residues frequently mutated in clinical immune escape variants, provides a molecular explanation for why immunotherapy for HBV infection may require combinations of complementary bNAbs.
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Affiliation(s)
- Qiao Wang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China.
| | - Eleftherios Michailidis
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Yingpu Yu
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Zijun Wang
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Arlene M Hurley
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Deena A Oren
- Structural Biology Resource Center, The Rockefeller University, New York, NY 10065, USA
| | - Christian T Mayer
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Anna Gazumyan
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Zhenmi Liu
- West China School of Public Health, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yunjiao Zhou
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Till Schoofs
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Kai-Hui Yao
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Jan P Nieke
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Jianbo Wu
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Qingling Jiang
- West China School of Public Health, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Chenhui Zou
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA; Division of Gastroenterology and Hepatology, Weill Cornell Medicine, New York, NY 10065, USA
| | - Mohanmmad Kabbani
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Corrine Quirk
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Thiago Oliveira
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Kalsang Chhosphel
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Qianqian Zhang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - William M Schneider
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Cyprien Jahan
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Tianlei Ying
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Jill Horowitz
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Marina Caskey
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Mila Jankovic
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Davide F Robbiani
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA
| | - Yumei Wen
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Ype P de Jong
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA; Division of Gastroenterology and Hepatology, Weill Cornell Medicine, New York, NY 10065, USA.
| | - Charles M Rice
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065, USA
| | - Michel C Nussenzweig
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA
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Khalili S, Rasaee MJ, Mousavi SL, Amani J, Jahangiri A, Borna H. In silico Prediction and in vitro Verification of a Novel Multi-Epitope Antigen for HBV Detection. MOLECULAR GENETICS MICROBIOLOGY AND VIROLOGY 2018. [DOI: 10.3103/s0891416817040097] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Gao Y, Zhang TY, Yuan Q, Xia NS. Antibody-mediated immunotherapy against chronic hepatitis B virus infection. Hum Vaccin Immunother 2017; 13:1768-1773. [PMID: 28521640 DOI: 10.1080/21645515.2017.1319021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The currently available drugs to treat hepatitis B virus (HBV) infection include interferons and nucleos(t)ide analogs, which can only induce disease remission and are inefficient for the functional cure of patients with chronic HBV infection (CHB). Since high titers of circulating hepatitis B surface antigen (HBsAg) may be essential to exhaust the host anti-HBV immune response and they cannot be significantly reduced by current drugs, new antiviral strategies aiming to suppress serum hepatitis B surface antigen (HBsAg) could help restore virus-specific immune responses and promote the eradication of the virus. As an alternative strategy, immunotherapy with HBsAg-specific antibodies has shown some direct HBsAg suppression effects in several preclinical and clinical trial studies. However, most described previously HBsAg-specific antibodies only had very short-term HBsAg suppression effects in CHB patients and animal models mimicking persistent HBV infection. More-potent antibodies with long-lasting HBsAg clearance effects are required for the development of the clinical application of antibody-mediated immunotherapy for CHB treatment. Our recent study described a novel mAb E6F6 that targets a unique epitope on HBsAg. It could durably suppress the levels of HBsAg and HBV DNA via Fcγ receptor-dependent phagocytosis in vivo. In this commentary, we summarize the current research progress, including the therapeutic roles and mechanisms of antibody-mediated HBV clearance as well as the epitope-determined therapeutic potency of the antibody. These insights may provide some clues and guidance to facilitate the development of therapeutic antibodies against persistent viral infection.
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Affiliation(s)
- Ying Gao
- a State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics , School of Public Health, Xiamen University , Xiamen , China.,b National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Life Science , Xiamen University , Xiamen , China
| | - Tian-Ying Zhang
- a State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics , School of Public Health, Xiamen University , Xiamen , China.,b National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Life Science , Xiamen University , Xiamen , China
| | - Quan Yuan
- a State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics , School of Public Health, Xiamen University , Xiamen , China.,b National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Life Science , Xiamen University , Xiamen , China
| | - Ning-Shao Xia
- a State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics , School of Public Health, Xiamen University , Xiamen , China.,b National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Life Science , Xiamen University , Xiamen , China
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De A, Roy S, Sukla S, Ansari A, Biswas S. Occult Hepatitis B Virus Infections (Often with Human Herpesvirus 7 Co-Infection) Detected in Pityriasis rosea Patients: A Pilot Study. Indian J Dermatol 2017; 62:598-605. [PMID: 29263533 PMCID: PMC5724307 DOI: 10.4103/ijd.ijd_235_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Background The etiopathogenesis of Pityriasis rosea (PR), a papulo-squamous skin disease, remains elusive and hypothesized to be caused primarily by human herpesvirus (HHV) 6 or 7 or immune dysfunction. Aims The recent increasing incidences of hepatitis B virus (HBV) infections, including asymptomatic occult HBV infections (OBIs), in a densely populated city in India, prompted us to investigate whether PR patients (from varied socioeconomic and immune status) harbor the underlying HBV infections. These cases were also investigated for HHV 6 and 7 infections. Materials and Methods DNA from ethylenediaminetetraacetic acid blood samples from PR-diagnosed individuals (n = 13; mostly young adults) and healthy controls (n = 11) were subjected to virus gene-specific polymerase chain reactions (PCRs) for HBV and HHV 6 and 7. PCR products of expected length, when observed, were sequenced (bidirectional) using overlapping primers. Sequences were identified by NCBI BLAST and analyzed by multiple sequence alignment and phylogenetic studies. The blood samples were tested for HBsAg by EIA. Results In 5/13 PR samples, only HBV DNA (4/5 being HBsAg negative) was detected, providing first-time evidence that PR may be manifested in asymptomatic HBV carriers. 6/13 cases were HHV 7 (not HHV 6) DNA positive, providing confirmatory molecular genetic evidence for the first time of PR association with HHV 7 from India. Surprisingly, 5/6 HHV 7-positive PR cases were also HBV positive. Overall, 10/13 PR samples showed evidence of HBV infection. 8/13 were OBI, harboring at least one OBI-signature S protein mutation. All healthy controls were HBsAg EIA and PCR negative. Conclusions 77% of PR patients presented the evidence of underlying HBV infection (genotype D2), suggestive of horizontal HBV transmission. This warrants for mass HBV vaccination. PR patients should be tested for underlying virus infections for appropriate therapy and management.
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Affiliation(s)
- Abhishek De
- Department of Dermatology, Calcutta National Medical College and Hospital, Kolkata, West Bengal, India
| | - Subrata Roy
- Infectious Diseases & Immunology Division, CSIR Indian Institute of Chemical Biology, Kolkata, West Bengal, India
| | - Soumi Sukla
- Infectious Diseases & Immunology Division, CSIR Indian Institute of Chemical Biology, Kolkata, West Bengal, India
| | - Asad Ansari
- Department of Dermatology, Calcutta National Medical College and Hospital, Kolkata, West Bengal, India
| | - Subhajit Biswas
- Infectious Diseases & Immunology Division, CSIR Indian Institute of Chemical Biology, Kolkata, West Bengal, India
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Chaouch H, Taffon S, Villano U, Equestre M, Bruni R, Belhadj M, Hannachi N, Aouni M, Letaief A, Ciccaglione AR. Naturally Occurring Surface Antigen Variants of Hepatitis B Virus in Tunisian Patients. Intervirology 2016; 59:36-47. [PMID: 27544241 DOI: 10.1159/000445894] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 04/02/2016] [Indexed: 11/19/2022] Open
Abstract
In Tunisia, the prevalence of naturally occurring surface (S) gene variants of hepatitis B virus (HBV) has not been determined. In the present study, the prevalence of these variants was examined in terms of the clinical and viral state in a series of 99 Tunisian patients with HBV infection. The S genes were amplified and directly sequenced. Genotype D was predominant (98%), 40.4% isolates belonged to subgenotypes D7 and 1 to subgenotype D2. The most common subtype was ayw2 (95.9%). In total, 60.6% of the studied strains harbored S mutations. Several novel mutation patterns were detected. Interestingly, the presence of S mutations was significantly correlated with the D7 subgenotype, low HBV DNA and advancing age (≥35 years), and tended to be higher in liver cirrhosis than in chronic infection. The global prevalence of the major hydrophilic region variants was 12.1%, with substitution S143L/T as the most frequent (4%). Only 33.9% of S substitutions produced amino acid changes in the polymerase gene. In conclusion, a high prevalence of naturally occurring HBsAg variants was observed among Tunisian HBV carriers. Natural viral variability in a geographical region and duration of infection are among the major factors associated with the occurrence of S mutations.
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Affiliation(s)
- Houda Chaouch
- Department of Infectious Diseases, Viral Hepatitis Research Unit (UR12SP35), University Hospital Farhat Hached, Sousse, Tunisia
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Kucinskaite-Kodze I, Pleckaityte M, Bremer CM, Seiz PL, Zilnyte M, Bulavaite A, Mickiene G, Zvirblis G, Sasnauskas K, Glebe D, Zvirbliene A. New broadly reactive neutralizing antibodies against hepatitis B virus surface antigen. Virus Res 2016; 211:209-21. [DOI: 10.1016/j.virusres.2015.10.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 10/28/2015] [Accepted: 10/28/2015] [Indexed: 12/20/2022]
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9
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Ultradeep Sequencing for Detection of Quasispecies Variants in the Major Hydrophilic Region of Hepatitis B Virus in Indonesian Patients. J Clin Microbiol 2015. [PMID: 26202119 DOI: 10.1128/jcm.00602-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Quasispecies of hepatitis B virus (HBV) with variations in the major hydrophilic region (MHR) of the HBV surface antigen (HBsAg) can evolve during infection, allowing HBV to evade neutralizing antibodies. These escape variants may contribute to chronic infections. In this study, we looked for MHR variants in HBV quasispecies using ultradeep sequencing and evaluated the relationship between these variants and clinical manifestations in infected patients. We enrolled 30 Indonesian patients with hepatitis B infection (11 with chronic hepatitis and 19 with advanced liver disease). The most common subgenotype/subtype of HBV was B3/adw (97%). The HBsAg titer was lower in patients with advanced liver disease than that in patients with chronic hepatitis. The MHR variants were grouped based on the percentage of the viral population affected: major, ≥20% of the total population; intermediate, 5% to <20%; and minor, 1% to <5%. The rates of MHR variation that were present in the major and intermediate viral population were significantly greater in patients with advanced liver disease than those in chronic patients. The most frequent MHR variants related to immune evasion in the major and intermediate populations were P120Q/T, T123A, P127T, Q129H/R, M133L/T, and G145R. The major population of MHR variants causing impaired of HBsAg secretion (e.g., G119R, Q129R, T140I, and G145R) was detected only in advanced liver disease patients. This is the first study to use ultradeep sequencing for the detection of MHR variants of HBV quasispecies in Indonesian patients. We found that a greater number of MHR variations was related to disease severity and reduced likelihood of HBsAg titer.
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10
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Luongo M, Critelli R, Grottola A, Gitto S, Bernabucci V, Bevini M, Vecchi C, Montagnani G, Villa E. Acute hepatitis B caused by a vaccine-escape HBV strain in vaccinated subject: sequence analysis and therapeutic strategy. J Clin Virol 2014; 62:89-91. [PMID: 25542480 DOI: 10.1016/j.jcv.2014.11.029] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 11/18/2014] [Accepted: 11/23/2014] [Indexed: 12/22/2022]
Abstract
HBV vaccine contains the 'a' determinant region, the major immune-target of antibodies (anti-HBs). Failure of immunization may be caused by vaccine-induced or spontaneous 'a' determinant surface gene mutants. Here, we evaluate the possible lack of protection by HBV vaccine, describing the case of an acute hepatitis B diagnosed in a 55-year-old Caucasian male unpaid blood donor, vaccinated against HBV. Sequencing data for preS-S region revealed multiple point mutations. Of all the substitutions found, Q129H, located in the "a" determinant region of HBsAg, can alter antigenicity, leading to mutants. This mutant may cause vaccine failure especially when associated with high viremia of infecting source.
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Affiliation(s)
- Monica Luongo
- Gastroenterology Unit, Department of Internal Medicine, Italy
| | - Rosina Critelli
- Gastroenterology Unit, Department of Internal Medicine, Italy
| | - Antonella Grottola
- Microbiology and Virology Service, Department of Diagnostic and Laboratory Services and Legal Medicine, Italy
| | - Stefano Gitto
- Gastroenterology Unit, Department of Internal Medicine, Italy
| | | | - Mirco Bevini
- Blood Transfusion Center, Department of Oncology, Hematology and Respiratory Diseases, University of Modena and Reggio Emilia, Azienda Ospedaliero-Universitaria Policlinico, Modena, Italy
| | - Chiara Vecchi
- Blood Transfusion Center, Department of Oncology, Hematology and Respiratory Diseases, University of Modena and Reggio Emilia, Azienda Ospedaliero-Universitaria Policlinico, Modena, Italy
| | - Giuliano Montagnani
- Blood Transfusion Center, Department of Oncology, Hematology and Respiratory Diseases, University of Modena and Reggio Emilia, Azienda Ospedaliero-Universitaria Policlinico, Modena, Italy
| | - Erica Villa
- Gastroenterology Unit, Department of Internal Medicine, Italy.
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11
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Chenari M, Norouzi M, Ghalichi L, Rezaee A, Yari A, Alavian SM, Jazayeri SM. Characterization of overt and occult hepatitis B virus infection among HTLV-1 positive healthy carriers in the Northeast of Iran; AN HTLV-I endemic area. J Med Virol 2014; 86:1861-7. [PMID: 25132488 DOI: 10.1002/jmv.24046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2014] [Indexed: 12/23/2022]
Abstract
To date, no studies have provided data on hepatitis B virus (HBV) prevalence among asymptomatic, healthy human T-lymphotropic virus (HTLV-I) positive carriers. This sero- and molecular epidemiology study was performed on patients in the Northeast of Iran, which is an endemic area for HTLV-I infection. A total of 109 sera were collected from HTLV-I positive healthy carriers who were admitted to Ghaem Hospital, Mashhad City. All were tested for HBV serology and subsequently, real time PCR was carried out on the samples, regardless of the results of the serology. Standard PCR and direct sequencing were applied on positive samples. All cases were negative for HBsAg, Anti-HBc, and anti-HBs were positive in 34 (31.1%), and 35 (32%) individuals, respectively. There were 19 (17.4%) cases that were positive only for anti-HBs, and they had already received HBV vaccine. 16 (15%) were positive for both anti-HBs and anti-HBc, indicating a past-resolved HBV infection. 18 (16.5%) were isolated as anti-HBc, and 56 (51.3%) were negative for all HBV serological markers. Only one subject (0.9%) had detectable HBV DNA (2153 copy/ml), and assigned as being an occult HBV infection. The low prevalence of HBsAg, despite the high percentage of anti-HBc positive cases, might be related to the suppression effect of HTLV-I on surface protein expression. The low prevalence of HBV infection among HTLV-I positive healthy carriers from an endemic region, indicates that the epidemiology of HTLV-I and HBV coinfection is related to the endemicity of HBV in that region, rather than HTLV-I endemicity.
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Affiliation(s)
- Maryam Chenari
- Hepatitis B Molecular Laboratory, Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
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12
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Golsaz Shirazi F, Mohammadi H, Amiri MM, Singethan K, Xia Y, Bayat AA, Bahadori M, Rabbani H, Jeddi-Tehrani M, Protzer U, Shokri F. Monoclonal antibodies to various epitopes of hepatitis B surface antigen inhibit hepatitis B virus infection. J Gastroenterol Hepatol 2014; 29:1083-91. [PMID: 24325676 DOI: 10.1111/jgh.12483] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/13/2013] [Indexed: 12/29/2022]
Abstract
BACKGROUND AND AIM Antibodies against the "a" determinant of hepatitis B surface antigen (HBsAg) are able to neutralize circulating hepatitis B virus (HBV) particles and prevent HBV infection. It has been proposed that a single amino acid exchange may allow the virus to escape the immune response. We used a set of monoclonal antibodies (MAbs) to investigate whether a single mutation may account for virus escape from humoral immunity. METHODS Nine murine HBsAg-specific MAbs were raised. Reactivity of all antibodies with 14 recombinant mutants of HBsAg was assessed by ELISA. HBV infection of HepaRG cells was used to evaluate viral neutralization capacity of MAbs in vitro. RESULTS All MAbs were able to inhibit the establishment of HBV infection in a dose-dependent fashion, but recognition of HBsAg variants varied. The MAbs were classified into three subgroups based on their pattern of reactivity to the HBsAg variants. Accordingly, three MAbs showed weak reactivity (< 40%) to variants with mutations within the first loop of "a" determinant, five MAbs displayed negligible binding to variants with mutations within the second loop, and one MAb lost its binding to variants having mutations in both loops of the "a" determinant. CONCLUSIONS Our results indicate that antibodies against different epitopes of the "a" determinant of HBsAg are able to neutralize HBV. It seems that mutations within a single or a limited number of amino acids within this determinant can hardly result in viral escape. These results have important implications for the development of antibody-based therapies against HBV.
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Affiliation(s)
- Forough Golsaz Shirazi
- Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
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13
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Tuteja A, Siddiqui AB, Madan K, Goyal R, Shalimar, Sreenivas V, Kaur N, Panda SK, Narayanasamy K, Subodh S, Acharya SK. Mutation profiling of the hepatitis B virus strains circulating in North Indian population. PLoS One 2014; 9:e91150. [PMID: 24637457 PMCID: PMC3956465 DOI: 10.1371/journal.pone.0091150] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 02/07/2014] [Indexed: 12/11/2022] Open
Abstract
AIMS The aim of this study was to investigate the genomic mutations in the circulating Hepatitis B virus strains causing infection in the Indian population. Further, we wanted to analyze the biological significance of these mutations in HBV mediated disease. METHODS 222 HBsAg positive patients were enrolled in the study. The genotype and mutation profile was determined for the infecting HBV isolate by sequencing overlapping fragments. These sequences were analyzed by using different tools and compared with previously available HBV sequence information. Mutation Frequency Index (MFI) for the Genes and Diagnosis group was also calculated. RESULTS HBV Genotype D was found in 55% (n = 121) of the patient group and genotype A was found in 30% (n = 66) of samples. The majority (52%) of the HBV-infected individuals in the present study were HBeAg-negative in all the age groups studied. Spontaneous drug associated mutations implicated in resistance to antiviral therapy were also identified in about quarter of our patients, which is of therapeutic concern. The MFI approach used in the study indicated that Core peptide was the most conserved region in both genotypes and Surface peptide had highest mutation frequency. Few mutations in X gene (T36A and G50R) showed high frequency of association with HCC. A rare recombinant strain of HBV genotype A and D was also identified in the patient group. CONCLUSIONS HBV genotype D was found out to be most prevalent. More than half of the patients studied had HBeAg negative disease. Core region was found to be most conserved. Drug Associated mutations were detected in 22% of the patient group and T36A and G50R mutations in X gene were found to be associated with HCC.
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Affiliation(s)
- Amit Tuteja
- Institute of Molecular Medicine, New Delhi, India
- Amity Institute of Biotechnology, Amity University, Noida, India
| | | | - Kaushal Madan
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - Rohit Goyal
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | - Shalimar
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
| | | | - Navkiran Kaur
- Amity Institute of Biotechnology, Amity University, Noida, India
| | - Subrat K. Panda
- Department of Pathology, All India Institute of Medical Sciences, New Delhi, India
| | | | - Swati Subodh
- Institute of Molecular Medicine, New Delhi, India
- Open Source Drug Discovery Unit, Council of Scientific & Industrial Research, New Delhi, India
| | - Subrat K. Acharya
- Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi, India
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14
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Chudy M, Scheiblauer H, Hanschmann KM, Kress J, Nick S, Wend U, Schüttler C, Nübling CM, Gerlich WH. Performance of hepatitis B surface antigen tests with the first WHO international hepatitis B virus genotype reference panel. J Clin Virol 2013; 58:47-53. [PMID: 23829967 DOI: 10.1016/j.jcv.2013.06.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/23/2013] [Accepted: 06/09/2013] [Indexed: 12/16/2022]
Abstract
BACKGROUND Standardization of hepatitis B surface antigen (HBsAg) tests is indispensable for consistent quality and comparability. Ideally, the assays should detect all known hepatitis B virus (HBV) genotypes equally well. OBJECTIVE Development of an HBV genotype reference panel for HBsAg assays representing the most prevalent HBV subgenotypes to address commutability and traceability of the heat-inactivated 2nd WHO International Standard (IS) for HBsAg in relation to native HBsAg and to HBV genotypes. STUDY DESIGN An HBV panel of 15 non-inactivated lyophilized specimens representing the subgenotypes A1, A2, B1, B2, C2, D1-D3, E, F2, and H was evaluated in parallel to the IS by 15 laboratories using 19 different HBsAg tests and tree unitages. The virus content of the samples was reduced by ultracentrifugation and dilution to <2×10(4) IU HBV DNA/mL. RESULTS Twenty-two qualitative and 6 quantitative data sets were evaluated. Overall, the results demonstrated consistent detection of HBV genotypes by the majority of tests with a mean potency variability relative to the IS of 36%. Some assays showed significant genotype-dependent differences in analytical sensitivity. Some tests were more sensitive with the IS, others less. On average, one IU HBsAg corresponded to 0.88±0.20 ng HBsAg protein. CONCLUSIONS The panel was accepted by the WHO as the "1st International Reference Panel for HBV genotypes for HBsAg-based assays". The panel is a helpful complementation to the IS to validate HBV genotype specific analytical test sensitivities.
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Affiliation(s)
- M Chudy
- Section of Molecular Virology, Paul-Ehrlich-Institut, Langen, Germany.
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15
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Khedive A, Norouzi M, Ramezani F, Karimzadeh H, Alavian SM, Malekzadeh R, Montazeri G, Nejatizadeh A, Ziaee M, Abedi F, Ataei B, Yaran M, Sayad B, Somi MH, Sarizadeh G, Sanei-Moghaddam I, Mansour-Ghanaei F, Rafatpanah H, Pourhosseingholi MA, Keyvani H, Kalantari E, Saberifiroozi M, Judaki MA, Ghamari S, Daram M, Mahabadi M, Fazeli Z, Goodarzi Z, Poortahmasebi V, Jazayeri SM. Hepatitis B virus surface protein mutations clustered mainly in CTL immune epitopes in chronic carriers: results of an Iranian nationwide study. J Viral Hepat 2013; 20:494-501. [PMID: 23730843 DOI: 10.1111/jvh.12045] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 11/27/2012] [Indexed: 12/14/2022]
Abstract
Mutations within the coding region of hepatitis B surface antigen (HBsAg) have been found naturally in chronic carriers. To characterize the mutations of HBsAg from Iranian chronic carriers who were vaccine and/or medication naive. The surface genes from 360 patients were amplified and directly sequenced. The distribution of amino acid substitutions was classified according to different immune epitopes of the surface protein. All isolates belonged to genotype D. 222 (61.6%) of 360 patients contained at least one amino acid substitution. 404 (74.5%) of 542 amino acid changes occurred in different immune epitopes of HBsAg, of which 112 (27.7%) in 32 residues of B-cell epitopes (62 in the 'a' determinant); 111 (27.4%) in 32 residues of T helper; and 197 (48.7%) in 32 residues inside cytotoxic T lymphocyte (CTL) epitopes. One Th (186-197) and two CTL (28-51 and 206-215) epitopes were found to be hotspot motifs for the occurrence of 213 (52.7%) substitutions. 20 stop codons were identified in different epitopes. There was a significant association between amino acid substitutions and anti-HBe seropositivity; however, the correlation between such changes with viral load and ALT levels was not significant. In chronic hepatitis B virus(HBV) carriers, positive selection in particular outside the 'a' determinant appeared to exert influence on the surface proteins. These changes could be immune escape mutations naturally occurring due to the host immune surveillance especially at the T-cell level.
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Affiliation(s)
- A Khedive
- Hepatitis B Molecular Laboratory, Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
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16
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Ijaz S, Szypulska R, Andrews N, Tedder RS. Investigating the impact of hepatitis B virus surface gene polymorphism on antigenicity using ex vivo phenotyping. J Gen Virol 2012; 93:2473-2479. [DOI: 10.1099/vir.0.044305-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The hepatitis B virus (HBV) surface antigen (HBsAg) is a complex protein, and understanding accurately the impact of amino acid changes on the antigenicity of the immunodominant a determinant must take this complexity into consideration. Epitope mapping with four mAbs was used to phenotype HBsAg directly from patients’ sera to investigate the effect of mutations in their native genetic backbone. The expected mAb reactivity was established initially for samples harbouring ‘wild-type’ HBsAg sequences across genotypes A–E. The alteration of HBsAg antigenicity, defined by mAb epitope loss, was demonstrated in a number of samples with sequence-inferred amino acid changes. Individual mutations within the mapped epitopes to which the mAbs were directed usually affected their binding. However, the loss of more than one epitope was observed as the number of mutations within a sequence increased. Conversely, not all mutations occurring in the a determinant altered the HBsAg conformation. The genotype backbone, the specific amino acid substitution and amino acid changes occurring outside the major antigenic region appeared to be important in determining expression of the predicted epitope loss. These data clearly demonstrate that sequence-based methods alone may not accurately define HBsAg phenotype. This phenotyping methodology allows for the rapid and accurate identification of antigenically altered viruses and will greatly enhance current HBV surveillance, research and diagnostic activities. The data generated can be used to inform on public health issues relating to prevalence, transmission and impact of HBsAg mutants in HBV-infected populations.
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Affiliation(s)
- Samreen Ijaz
- Blood Borne Virus Unit, Virus Reference Department, Microbiology Services-Colindale, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, UK
| | - Renata Szypulska
- Blood Borne Virus Unit, Virus Reference Department, Microbiology Services-Colindale, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, UK
| | - Nick Andrews
- Statistics, Modelling and Economics Department, Health Protection Services-Colindale, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, UK
| | - Richard S. Tedder
- Division of Infection and Immunity, University College London, Gower Street, London WC1E 6BT, UK
- Transfusion Microbiology, NHS Blood and Transplant, Colindale Avenue, London NW9 5BG, UK
- Blood Borne Virus Unit, Virus Reference Department, Microbiology Services-Colindale, Health Protection Agency, 61 Colindale Avenue, London NW9 5EQ, UK
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17
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18
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Alavian SM, Carman WF, Jazayeri SM. HBsAg variants: diagnostic-escape and diagnostic dilemma. J Clin Virol 2012; 57:201-8. [PMID: 22789139 DOI: 10.1016/j.jcv.2012.04.027] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 01/23/2012] [Accepted: 04/18/2012] [Indexed: 12/11/2022]
Abstract
A wide variety of commercial assays is available for the detection of hepatitis B surface antigen (HBsAg). Clearly, the sensitivity of an assay to detect a variant is dependent on the anti-HBs usage. Thus, it is not surprising that there are examples of variants that cannot be detected by all assays. Data from Europe, Asia and Africa about HBsAg variants which are not recognized by either monoclonal or polyclonal antibodies specific for wild-type group 'a' determinant, but positive by DNA polymerase chain reaction (PCR) in chronic patients and from vaccinated children are increasing. This would impose a challenge for public health issues of hepatitis B virus. In this review we tried to summarize the discrepancies between results of HBsAg assays and to explain some rationales for these inconsistencies.
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Affiliation(s)
- Seyed Moayed Alavian
- Baqiyatallah University of Medical Sciences, Baqiyatallah Research Centre for Gastroenterology and Liver Disease, Tehran, Iran
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Abstract
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.
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Affiliation(s)
- Michael A Purdy
- Division of Viral Hepatitis, MS-A33, Centers for Disease Control and Prevention, 1600 Clifton Rd NE, Atlanta, GA 30329, USA
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20
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Neumann AU, Phillips S, Levine I, Ijaz S, Dahari H, Eren R, Dagan S, Naoumov NV. Novel mechanism of antibodies to hepatitis B virus in blocking viral particle release from cells. Hepatology 2010; 52:875-85. [PMID: 20593455 PMCID: PMC3086357 DOI: 10.1002/hep.23778] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
UNLABELLED Antibodies are thought to exert antiviral activities by blocking viral entry into cells and/or accelerating viral clearance from circulation. In particular, antibodies to hepatitis B virus (HBV) surface antigen (HBsAg) confer protection, by binding circulating virus. Here, we used mathematical modeling to gain information about viral dynamics during and after single or multiple infusions of a combination of two human monoclonal anti-HBs (HepeX-B) antibodies in patients with chronic hepatitis B. The antibody HBV-17 recognizes a conformational epitope, whereas antibody HBV-19 recognizes a linear epitope on the HBsAg. The kinetic profiles of the decline of serum HBV DNA and HBsAg revealed partial blocking of virion release from infected cells as a new antiviral mechanism, in addition to acceleration of HBV clearance from the circulation. We then replicated this approach in vitro, using cells secreting HBsAg, and compared the prediction of the mathematical modeling obtained from the in vivo kinetics. In vitro, HepeX-B treatment of HBsAg-producing cells showed cellular uptake of antibodies, resulting in intracellular accumulation of viral particles. Blocking of HBsAg secretion also continued after HepeX-B was removed from the cell culture supernatants. CONCLUSION These results identify a novel antiviral mechanism of antibodies to HBsAg (anti-HBs) involving prolonged blocking of the HBV and HBsAg subviral particles release from infected cells. This may have implications in designing new therapies for patients with chronic HBV infection and may also be relevant in other viral infections.
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Affiliation(s)
- Avidan U. Neumann
- Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Sandra Phillips
- Institute of Hepatology, University College London, United Kingdom
| | - Idit Levine
- Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Samreen Ijaz
- Hepatitis Laboratory, Health Protection Agency, Colindale, United Kingdom
| | - Harel Dahari
- Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel,Department of Medicine, Section of Hepatology, University of Illinois at Chicago, Chicago, IL USA
| | - Rachel Eren
- XTL Biopharmaceuticals Ltd., Kiryat Weizmann Science Park, Rehovot, Israel
| | - Shlomo Dagan
- XTL Biopharmaceuticals Ltd., Kiryat Weizmann Science Park, Rehovot, Israel
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Scheiblauer H, El-Nageh M, Diaz S, Nick S, Zeichhardt H, Grunert HP, Prince A. Performance evaluation of 70 hepatitis B virus (HBV) surface antigen (HBsAg) assays from around the world by a geographically diverse panel with an array of HBV genotypes and HBsAg subtypes. Vox Sang 2009; 98:403-14. [PMID: 20412171 PMCID: PMC2860763 DOI: 10.1111/j.1423-0410.2009.01272.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND AND OBJECTIVES This study was conducted by the International Consortium for Blood Safety (ICBS) to identify high-quality test kits for detection of hepatitis B virus (HBV) surface antigen (HBsAg) for the benefit of developing countries. MATERIALS AND METHODS The 70 HBsAg test kits from around the world were evaluated comparatively for their clinical sensitivity, analytical sensitivity, sensitivity to HBV genotypes and HBsAg subtypes, and specificity using 394 (146 clinical, 48 analytical and 200 negative) ICBS Master Panel members of diverse geographical origin comprising the major HBV genotypes A-F and the HBsAg subtypes adw2,4, adr and ayw1-4. RESULTS Seventeen HBsAg enzyme immunoassay (EIA) kits had high analytical sensitivity <0.13 IU/ml, showed 100% diagnostic sensitivity, and were even sensitive for the various HBV variants tested. An additional six test kits had high sensitivity (<0.13 IU/ml) but missed HBsAg mutants and/or showed reduced sensitivity to certain HBV genotypes. Twenty HBsAg EIA kits were in the sensitivity range of 0.13-1 IU/ml. The other eight EIAs and the 19 rapid assays had analytical sensitivities of 1 to >4 IU/ml. These assays were falsely negative for 1-4 clinical samples and 17 of these test kits showed genotype dependent sensitivity reduction. Analytical sensitivities for HBsAg of >1 IU/ml significantly reduce the length of the HBsAg positive period which renders them less reliable for detecting HBsAg in asymptomatic HBV infections. Reduced sensitivity for HBsAg with genetic diversity of HBV occurred with genotypes/subtypes D/ayw3, E/ayw4, F/adw4 and by S gene mutants. Specificity of the HBsAg assays was >or=99.5% in 57 test kits and 96.4-99.0% in the remaining test kits. CONCLUSION Diagnostic efficacy of the evaluated HBsAg test kits differed substantially. Laboratories should therefore be aware of the analytical sensitivity for HBsAg and check for the relevant HBV variants circulating in the relevant population.
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22
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Scheiblauer H, El-Nageh M, Diaz S, Nick S, Zeichhardt H, Grunert HP, Prince A. Performance evaluation of 70 hepatitis B virus (HBV) surface antigen (HBsAg) assays from around the world by a geographically diverse panel with an array of HBV genotypes and HBsAg subtypes. Vox Sang 2009. [PMID: 20412171 DOI: 10.1111/j.1423-0410.2009.01272] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND OBJECTIVES This study was conducted by the International Consortium for Blood Safety (ICBS) to identify high-quality test kits for detection of hepatitis B virus (HBV) surface antigen (HBsAg) for the benefit of developing countries. MATERIALS AND METHODS The 70 HBsAg test kits from around the world were evaluated comparatively for their clinical sensitivity, analytical sensitivity, sensitivity to HBV genotypes and HBsAg subtypes, and specificity using 394 (146 clinical, 48 analytical and 200 negative) ICBS Master Panel members of diverse geographical origin comprising the major HBV genotypes A-F and the HBsAg subtypes adw2,4, adr and ayw1-4. RESULTS Seventeen HBsAg enzyme immunoassay (EIA) kits had high analytical sensitivity <0.13 IU/ml, showed 100% diagnostic sensitivity, and were even sensitive for the various HBV variants tested. An additional six test kits had high sensitivity (<0.13 IU/ml) but missed HBsAg mutants and/or showed reduced sensitivity to certain HBV genotypes. Twenty HBsAg EIA kits were in the sensitivity range of 0.13-1 IU/ml. The other eight EIAs and the 19 rapid assays had analytical sensitivities of 1 to >4 IU/ml. These assays were falsely negative for 1-4 clinical samples and 17 of these test kits showed genotype dependent sensitivity reduction. Analytical sensitivities for HBsAg of >1 IU/ml significantly reduce the length of the HBsAg positive period which renders them less reliable for detecting HBsAg in asymptomatic HBV infections. Reduced sensitivity for HBsAg with genetic diversity of HBV occurred with genotypes/subtypes D/ayw3, E/ayw4, F/adw4 and by S gene mutants. Specificity of the HBsAg assays was >or=99.5% in 57 test kits and 96.4-99.0% in the remaining test kits. CONCLUSION Diagnostic efficacy of the evaluated HBsAg test kits differed substantially. Laboratories should therefore be aware of the analytical sensitivity for HBsAg and check for the relevant HBV variants circulating in the relevant population.
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Beale MA, Ijaz S, Tedder RS. The genetic backbone modulates the phenotype of hepatitis B surface antigen mutants. J Gen Virol 2009; 91:68-73. [PMID: 19759242 DOI: 10.1099/vir.0.013078-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Hepatitis B virus (HBV) vaccine and diagnostic escape mutants are a growing concern. The principle target of detection, hepatitis B surface antigen (HBsAg), encoded by S, is completely overlapped by the reverse transcriptase encoding P. With the increased incidence of nucleos(t)ide analogue resistance altering P, the concurrent impact on S must be assessed. HBV DNA from 59 HBsAg-positive plasma samples was sequenced across the polymerase/surface region and the amino acid sequence of HBsAg was inferred. ELISAs were formatted containing individually bound monoclonal antibodies directed against three discrete epitopes on HBsAg. Similar point mutations occurring in different genotypes were shown to influence epitope conformation differently, indicating that the genetic backbone is a major factor in predicting phenotype. C-terminal changes associated with antiviral resistance were found to modulate epitope profiles of HBsAg. Treatment options which may promote drug resistance should be avoided to both protect antiviral treatment and prevent facilitation of vaccine and diagnostic escape mutants.
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Affiliation(s)
- Mathew A Beale
- Blood Borne Virus Unit, Virus Reference Department, Centre for Infections, Health Protection Agency, London, UK
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Sloan RD, Ijaz S, Moore PL, Harrison TJ, Teo CG, Tedder RS. Antiviral Resistance Mutations Potentiate hepatitis B virus Immune Evasion through Disruption of its Surface Antigen a Determinant. Antivir Ther 2008. [DOI: 10.1177/135965350801300313] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background The hepatitis B virus (HBV) pol gene overlaps the S gene encoding surface antigen (HBsAg). It has been reported previously that drug-induced changes in HBsAg alter its binding to sera from humans immunized against HBV. We investigate here the changes to specific epitopes in the a determinant (the major target of neutralizing antibody) caused by a number of drug-resistant mutations. Methods Recombinant HBsAgs, produced by transfection of Chinese hamster ovary cells with S gene plasmids into which lamivudine, adefovir and entecavir resistance and common antibody-escape mutations had been introduced, were probed with monoclonal antibodies to epitopes in the first and second loops of the a determinant. Results The mutations rtF166L/sF158Y (lamivudine-associated, compensatory) and rtI169T/sF161L (entecavir-associated, primary) acting alone, and the mutations rtV173L/sE164D (lamivudine-associated, compensatory) and rtSilent/sD144E (antibody escape-associated) each when combined with rtM204V/sI195M (lamivudine-associated, primary) led to decreases in antibody reactivity to epitopes in the first or second loop, or in both loops. The rtM204V/ sI195M+rtV173L/sE164D mutations yielded an epitope–antibody profile similar to the rtR153Q/sG145R vaccine escape mutant. The rtM204V/sI195M mutation combined with the rtF166L/sF158Y or rtR153Q/sG145R mutation restored reactivity to second-loop epitopes previously abrogated by single mutations. Conclusions Mutations associated with resistance to nucleos(t)ide analogue therapy, singly or in combination with each other or antibody escape-associated mutations, alter HBsAg immunoreactivity through concomitant amino acid substitutions at codons within and downstream of the a determinant. The findings have implications for understanding the native structure of HBsAg, optimizing treatment of chronic hepatitis B and evaluating the success of immunization programmes.
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Affiliation(s)
- Richard D Sloan
- Virus Reference Division, Centre for Infections, Health Protection Agency, London, UK
- Department of Infection, University College London, London, UK
- Present address: McGill AIDS Centre, Lady Davis Institute, Montreal, Canada
| | - Samreen Ijaz
- Virus Reference Division, Centre for Infections, Health Protection Agency, London, UK
| | - Penny L Moore
- Department of Medicine, University College London, London, UK
- Present address: National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Tim J Harrison
- Present address: McGill AIDS Centre, Lady Davis Institute, Montreal, Canada
| | - Chong-Gee Teo
- Virus Reference Division, Centre for Infections, Health Protection Agency, London, UK
- Present address: Division of Viral Hepatitis, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Richard S Tedder
- Virus Reference Division, Centre for Infections, Health Protection Agency, London, UK
- Department of Infection, University College London, London, UK
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Shin YW, Ryoo KH, Hong KW, Chang KH, Choi JS, So M, Kim PK, Park JY, Bong KT, Kim SH. Human monoclonal antibody against Hepatitis B virus surface antigen (HBsAg). Antiviral Res 2007; 75:113-20. [PMID: 17343928 DOI: 10.1016/j.antiviral.2007.01.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 01/09/2007] [Accepted: 01/09/2007] [Indexed: 11/19/2022]
Abstract
Hepatitis B virus (HBV) is one of the main pathogens responsible for hepatitis and hepatocellular carcinoma. Human plasma-derived Hepatitis B immune globulin (HBIG) is being used for prophylactic and liver transplantation currently. However, it may be necessary to replace a HBIG with a recombinant one because of limited availability of human plasma with high anti-HBsAg antibody titer and possible contamination of human pathogens. A Chinese hamster ovary (CHO) cell line, HB-C7A, was established which produces a fully human IgG1 that binds HBsAg. The HB-C7A exhibits approximately 2600 units/mg of antibody. The affinity (K(a)) of HB-C7A is 1.1 x 10(8) M(-1) by Biacore analysis and estimated 6.7-fold higher than that of Hepabig (a plasma-derived HBIG from Green Cross Corp., Yongin, Korea) by competition ELISA. The HB-C7A recognizes the conformational "a" determinant of HBsAg and binds HBV particle more efficiently than the Hepabig. The HB-C7A binds to HBV-infected human liver tissue but does not bind to normal human tissues. This HB-C7A has several advantages compared to plasma-derived Hepabig such as activity, safety and availability.
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Affiliation(s)
- Yong-Won Shin
- Antibody Engineering Laboratory, Research Center, Green Cross Corporation, 341 Bojeong-Dong, Giheung-Gu, Yongin City, Gyunggi-Do 446-799, Republic of Korea
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26
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Gibb R, Nimmo GR, O'Loughlin P, Lowe P, Drummond D. Detection of HBsAg mutants in a population with a low prevalence of hepatitis B virus infection. J Med Virol 2007; 79:351-5. [PMID: 17311336 DOI: 10.1002/jmv.20823] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Two independent studies were conducted to evaluate performance of two HBsAg immunoassay products performed on the Abbott ARCHITECT and Bayer ADVIA Centaur immunoassay analyzers. One was a retrospective study of 484 stored samples and the second was a prospective study of 349 samples from random population. In the process of the evaluation, a number of discordant samples from HBsAg-positive patients were found which led to the discovery of a number of HBsAg mutants in the general Australian population. Following viral DNA sequencing, these were identified as HBsAg escape mutants. Whilst the existence of HBsAg mutants has been well documented in various regions of the world, this is surprising in an area of low endemicity and demonstrates the necessity of an HBsAg assay to detect mutants reliably in a diagnostic situation where HBsAg is used as the only marker to detect an HBV infection. These studies demonstrate the ability of the Abbott ARCHITECT and AxSYM HBsAg immunoassays to detect these HBsAg mutations which were not detected by the Bayer ADVIA Centaur.
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Affiliation(s)
- Robert Gibb
- Queensland Health Pathology Service, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia.
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27
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Abstract
HBsAg screening is carried out routinely to detect hepatitis B virus (HBV) infection. The immunoassays used employ capture antibodies often having specificity for epitopes present on the antigenic (a) determinant of the HBsAg. Loss of detection may occur due to mutations within and/or outside of the a determinant that affect conformational epitope recognition or HBsAg secretion or expression. Most of the mutations associated with immune escape occur within the second loop of the a determinant. In order to detect these HBsAg mutants, antibodies to subdominant regions within the a determinant or outside of the HBsAg may be required, and this has been the focus of many recent studies. Any changes to immunoassay formulations should also address the possible effect of HBV genotypic polymorphisms on assay specificity and sensitivity. HBsAg mutants may also be identified through nucleic acid detection of HBV in serum. Various molecular analysis methods have been developed to provide specific and sensitive detection of HBsAg mutants, including sequencing, limiting dilution cloning PCR (LDC-PCR), gap ligase chain reaction (gLCR), and real time PCR. Sequencing the HBsAg coding region provides specific information on the nucleotide sequence; however, it is relatively insensitive for the detection of minority quasispecies. Other nucleic acid methods offer greater sensitivity for the detection of point mutations. To improve immunoassays, further research will be required to increase detection sensitivity and specificity. Ultimately, a better understanding of the structure of antibody-bound HBsAg will help identify the immunological targets required for the accurate detection of HBsAg in blood.
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Affiliation(s)
- Carla Osiowy
- Bloodborne Pathogens and Hepatitis, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.
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Srey CT, Ijaz S, Tedder RS, Monchy D. Characterization of hepatitis B surface antigen strains circulating in the Kingdom of Cambodia. J Viral Hepat 2006; 13:62-6. [PMID: 16364084 DOI: 10.1111/j.1365-2893.2005.00656.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A collection of hepatitis B surface antigen (HBsAg)-reactive serum specimens from the Pasteur Institute of Cambodia was investigated for the genotype, predicted serotype and the presence of diagnostically significant mutations in the surface protein. From a set of 794 samples, 15 were identified serologically to harbour possible HBsAg mutants and were investigated further. An additional 20 samples were included into the study for PCR and sequence analysis. Of the 22 samples which were HBV-DNA-positive, 16 were of genotype C with the remaining six being genotype B. Point mutations resulting in amino acid substitutions were noted in 10 samples. The majority of these mutations occurred outside the a determinant.
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Affiliation(s)
- C T Srey
- Institut Pasteur du Cambodge, Phnom Penh, Kingdom of Cambodia
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Hu H, Peng XM, Huang YS, Gu L, Xie QF, Gao ZL. Yeast expression and DNA immunization of hepatitis B virus S gene with second-loop deletion of α determinant region. World J Gastroenterol 2004; 10:2989-93. [PMID: 15378779 PMCID: PMC4576258 DOI: 10.3748/wjg.v10.i20.2989] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM: Immune escape mutations of HBV often occur in the dominant epitope, the second-loop of the a determinant of hepatitis B surface antigen (HBsAg). To let the hosts respond to the subdominant epitopes in HBsAg may be an effective way to decrease the prevalence of immune escape mutants. For this reason, a man-made clone of HBV S gene with the second-loop deletion was constructed. Its antigenicity was evaluated by yeast expression analysis and DNA immunization in mice.
METHODS: HBV S gene with deleted second-loop, amino acids from 139 to 145, was generated using splicing by overlap extension. HBV deleted S gene was then cloned into the yeast expression vector pPIC9 and the mammalian expression vector pcDNA3 to generate pHB-SDY and pHB-SD, respectively. The complete S gene was cloned into the same vectors as controls. The deleted recombinant HBsAg expressed in yeasts was detected using Abbott IMx HBsAg test kits, enzyme-linked immunoadsorbent assay (ELISA) and immune dot blotting to evaluate its antigenicity in vitro. The anti-HBs responses to DNA immunization in BALB/c mice were detected using Abbott IMx AUSAB test kits to evaluate the antigenicity of that recombinant protein in vivo.
RESULTS: Both deleted and complete HBsAg were successfully expressed in yeasts. They were intracellular expressions. The deleted HBsAg could not be detected by ELISA, in which the monoclonal anti-HBs against the α determinant was used, but could be detected by Abbott IMx and immune dot blotting, in which multiple monoclonal anti-HBs and polyclonal anti-HBs were used, respectively. The activity of the deleted HBsAg detected by Abbott IMx was much lower than that of complete HBsAg (the ratio of sample value/cut off value, 106 ± 26.7 vs 1814.4 ± 776.3, P < 0.01, t = 5.02). The anti-HBs response of pHB-SD to DNA immunization was lower than that of complete HBV S gene vector pHB (the positive rate 2/10 vs 6/10, 4.56 ± 3.52 mIU/mL vs 27.60 ± 17.3 mIU/mL, P = 0.02, t = 2.7).
CONCLUSIONS: HBsAg with deleted second-loop of the α determinant still has antigenicity, and can also raise weak anti-HBs response in mice to DNA immunization, suggesting that it is possible to develop a subdominant vaccine for preventing infections of immune escape mutants of HBV.
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Affiliation(s)
- Hui Hu
- Department of Infectious Diseases, the Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510630, Guangdong Province, China
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