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A novel rapid fluorescent lateral-flow immunoassay for hepatitis B virus genotyping Liuwei Song, Yingbin Wang, Linlin Fang, Yong Wu, Lin Yang, Jieyu Chen, Shengxiang Ge, Jing Zhang, Youzheng Xiong, Xiumei Deng, Xiaoping Min, Jun Zhang, Pei-Jer Chen, Quan Yuan, and Ningshao Xia Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/ac504832c • Publication Date (Web): 20 Apr 2015 Downloaded from http://pubs.acs.org on April 22, 2015
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Analytical Chemistry
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Title:
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A novel rapid fluorescent lateral-flow immunoassay for hepatitis B virus
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genotyping
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Running title:
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Fast HBV genotyping by LFIA
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Authors:
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Liu-Wei Song1,2,†, Ying-Bin Wang1,2,†, Lin-Lin Fang1,2, Yong Wu1,2, Lin Yang1,2,
10
Jie-Yu Chen5, Sheng-Xiang Ge1,2, Jing Zhang1,2, You-Zheng Xiong1,2,3, Xiu-Mei
11
Deng5, Xiao-Ping Min1,2,3,*, Jun Zhang1,2, Pei-Jer Chen4, Quan Yuan1,2,* and
12
Ning-Shao Xia1,2
13 14 15
†
These authors contributed equally to this work.
*
Co-corresponding authors
16 17
Author affiliations:
18
1
19
Diseases, State Key Laboratory of Molecular Vaccinology and Molecular
20
Diagnostics, School of Life Sciences, Xiamen University, China
21
2
22
3
National Institute of Diagnostics and Vaccine Development in Infectious
School of Public Health, Xiamen University, Xiamen, China School of Information Science and Engineering, Computer Science 1
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Department, Xiamen University, Xiamen, China 4
National Taiwan University College of Medicine, National Taiwan University,
25
Taipei, Taiwan
26
5
Xiamen Innovax Biotech Co., Ltd, Xiamen, China
27 28
Corresponding authors:
29
Address requests for reprints to: Q Yuan or XP Min, National Institute of
30
Diagnostics and Vaccine Development in Infectious Diseases, Xiamen
31
University, China. E-mail:
[email protected] or
[email protected]. Fax:
32
(86)-0592-2181258.
33 34
Funding
35
This work was supported by the National Scientific and Technological
36
Major Project (2012ZX10002005-001-001), the Key Research Item of Science
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and Technology of Fujian Province (2014Y0073), and the Fujian province
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science and technology project (2012Y4011).
39 40
Conflict of interest:
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Jie-Yu Chen and Xiu-Mei Deng are employees of the Xiamen Innovax Biotech
42
Co., Ltd. The other authors declare no competing interests.
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Key words: Hepatitis B virus, Genotype, Lateral flow immunoassay, 2
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Analytical Chemistry
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Fluorescent, Monoclonal antibody, Chronic hepatitis B
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Nonstandard abbreviations:
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LFIA, lateral flow immunoassay; mAb, monoclonal antibody; HBV, hepatitis B
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virus; ALT, alanine aminotransferase; HBsAg, hepatitis B surface antigen;
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HBeAg, hepatitis B e antigen; ULN, upper limit of normal; CI, confidence
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interval; SD, standard deviation.
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Abstract
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Hepatitis B virus (HBV) genotyping plays an important role in the clinical
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management of chronic hepatitis B (CHB) patients. However, the current
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nucleic
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inconvenient. Here, we developed a novel DNA-independent HBV genotyping
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tool based on a one-step fluorescent lateral flow immunoassay (LFIA).
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Epitope-targeting immunization and screening techniques were used to
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develop HBV genotype-specific monoclonal antibodies (mAbs). These mAbs
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were used to develop a multi-test LFIA with a matched scanning luminoscope
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for HBV genotyping (named the GT-LFIA). The performance of this novel
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assay was carefully evaluated in well-characterized clinical cohorts. The
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GT-LFIA, which can specifically differentiate HBV genotypes A, B, C and D in a
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pretreatment-free
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genotype-specific mAbs. The detection limits of the GT-LFIA for HBV
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genotypes A, B, C and D were 2.5-10.0 IU HBV surface antigen/mL,
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respectively. Among the sera from 456 CHB patients, 439 (96.3%, 95%
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confidence interval [CI]: 94.1–97.8%) were genotype-differentiable by the
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GT-LFIA and 437 (99.5%, 95% CI: 98.4-99.9%) were consistent with viral
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genome sequencing. In the 21 patients receiving nucleos(t)ide analogue
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therapy, for end-of-treatment specimens that were HBV DNA undetectable and
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were not applicable for DNA-dependent genotyping, the GT-LFIA presented
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genotyping results that were consistent with those obtained in pretreatment
acid-based
techniques
single
test,
are
was
expensive,
successfully
4
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time-consuming
developed
and
using
4
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specimens by viral genome sequencing and the GT-LFIA. In conclusion, the
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novel GT-LFIA is a convenient, fast and reliable tool for differential HBV
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genotyping, especially in patients with low or undetectable HBV DNA levels.
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Introduction
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The hepatitis B virus (HBV) is a serious, worldwide public health problem
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because HBV infection can cause hepatitis, liver cirrhosis (LC) and
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hepatocellular carcinoma (HCC), resulting in more than one million deaths
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annually1,2. HBV has been classified into 8 different genotypes (A–H) as
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determined by whole-genome sequence heterogeneity exceeding 8%3-6. The
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different genotypes exhibit distinct geographic distribution characteristics.
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Genotype A is prevalent in sub-Saharan Africa, North America and Europe,
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whereas B and C are prevalent in Asia, E is prevalent in Africa, F and H are
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prevalent in Central and South America, and D and G are present worldwide 1,7.
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Overall, the HBV genotypes A/D and B/C represent the predominant epidemic
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strains in Europe/North America and Asia, respectively.
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Evidence from clinical studies indicates that the HBV genotype
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significantly influences the natural history, liver disease progression and
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antiviral treatment response 8,9. The rate of chronicity of acute genotype A or D
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infections is higher than that of genotype B or C infections 9,10. HBV genotypes
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A and B are associated with higher rates of HBV e antigen (HBeAg)
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seroconversion and
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interferon-based treatment when compared with genotypes D and C,
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respectively. Additionally, when compared to patients with genotypes A and B,
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those with genotypes C and D have a higher risk of poor disease progression
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(LC and HCC)
9,11
HBV
surface antigen (HBsAg)
losses
following
. Moreover, recent studies have demonstrated that the HBV 6
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genotype significantly influences the on-treatment HBsAg kinetics and
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end-of-treatment (EOT) HBsAg levels, which are associated with long-term
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sustained virological responses and HBsAg losses, thus suggesting that
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genotype-specific monitoring timeframes and EOT thresholds could ameliorate
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the response-guided treatment (RGT) of chronic hepatitis B (CHB)
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Altogether, HBV genotyping can provide important information for the guidance
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of CHB clinical management.
12
.
The current techniques for HBV genotyping are mainly based on nucleic
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13
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acid tests (NATs) for genotype-specific sequences
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genome
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hybridization methods (e.g., the commercial INNO-LiPATM assay) 15, restriction
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fragment polymorphisms 16, multiplex nested polymerase chain reaction (PCR)
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17,18
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NAT-based techniques are expensive, time-consuming and inconvenient,
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given the requirement for a DNA extraction procedure. In this study, we aimed
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to develop a novel HBV DNA-independent genotyping tool based on a
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one-step fluorescent lateral flow immunoassay (LFIA) and genotype-specific
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monoclonal antibodies (mAbs), furthermore the new assay was fully evaluated.
sequencing
followed
by
, including direct whole
phylogenetic
, oligonucleotide microarray chips
19
analysis
and real-time PCR
14
20
,
reverse
. However,
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Materials and methods
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Development of HBV genotype-specific mAbs
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Epitopes in the preS2 regions were selected as the targets for HBV 7
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genotype-specific mAbs as described previously
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of the antibodies, epitope-targeting immunization and screening techniques
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were designed and performed as shown in Fig. 1. Briefly, the sequences of E1
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(aa 32–55 of HBV genotype A preS2), E2 (aa 33–52 of HBV genotype B
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preS2), E3 (aa 32–55 of HBV genotype C preS2) and E4 (aa 6–27 of HBV
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genotype D preS2) were engrafted into an HBc149 protein to construct
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chimeric virus-like particle proteins. The chimeric virus-like particles (VLPs)
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were produced in E. coli and purified as described previously
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HBc-E1, HBc-E2, HBc-E3 and HBc-E4 VLPs were used as immunogens to
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generate antibodies targeting the E1, E2, E3 and E4 epitopes, respectively, via
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standard hybridoma technology
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culture media from the HBV genotype A–D hybridoma cell clones were
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evaluated with a virus capture enzyme-linked immunosorbent assay (ELISA).
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The clones producing mAbs with differential binding to different HBV
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genotypes were preserved for further assessment. Finally, 4 HBV genotype
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specific mAbs 2B2, 16D12, 6H3 and 3E6 were developed. The sensitivity and
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specificity for detecting different HBV genotypes(A, B, C and D) of the 4 mAbs
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were evaluated by enzyme-linked immunosorbent assay(ELISA).
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LFIA for HBV genotyping
23
. To improve the efficiency
22
. The purified
. For screening, the binding activities of
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The LFIA test strip for HBV genotyping (GT-LFIA) is composed of a
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backing, sample pad, conjugate pad, nitrocellulose membrane (Millipore,
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Bedford, MA, USA) and absorbent pad (Jieyi Biotechnology, Shanghai, China). 8
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The strip was positioned as shown in Fig. 2A, wherein the ends of the
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components overlapped, thus ensuring a continuous flow of the sample
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solution via capillary action from the sample pad to the absorbent pad. An
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anti-HBsAg mAb (WTS; purchased from Wantai, Beijing, China) and
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biotinylated bovine serum albumin (BSA), both of which were conjugated to
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Fluoro-Max Fluorescent Nanoparticles (Excite at 333 nm and emit at 613 nm,
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Thermo Scientific, Rockford, IL, USA), were diluted in a blocking reagent and
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adsorbed onto the conjugate pad. On the nitrocellulose membrane, the
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genotype-specific mAbs 2B2, 16D12, 6H3 and 3E6, goat anti-HBsAg
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polyclonal (GAS) antibodies and streptavidin were immobilized on the A, B, C,
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D, S and CT capture lines, respectively (as shown in Fig. 2A). All the distances
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between the two adjacent lines are 3 mm except line S and A that is 4 mm. The
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strip was subsequently dried overnight at 37°C and kept dry at room
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temperature until use.
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For GT-LFIA-mediated detection, an 80-µL sample (serum or plasma) was
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directly pipetted onto the sample pad. Subsequently, the sample re-mobilized
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the dried conjugates and viral surface antigens, including L-HBsAg (containing
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the preS2 region), M-HBsAg (containing the preS2 region) and S-HBsAg (not
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containing the preS2 region), in the WTS-FP conjugate-bound sample as both
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migrated into the nitrocellulose membrane. The L/M-HBsAg-WTS-FP immune
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complexes in the samples were then captured by the 3E6, 6H3, 16D12 or 2B2
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antigens according to the viral antigen genotypes as they migrated past the 9
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lines
(D,
C,
B
and
A,
respectively).
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capture
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S-HBsAg-WTS-FP immune complexes and biotinylated BSA-FP were
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captured by the GAS antibody and streptavidin, which were immobilized on the
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S and CT lines, respectively. Excess reagents moved beyond the capture lines
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to be entrapped in the absorbent pad. The assay could be completed within 20
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minutes, and the fluorescent intensities of all test lines on the strip could be
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measured using a customized luminoscope reader (Fig. 2C).
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Sample collection
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The performance of the GT-LFIA was evaluated in three different cohorts. For
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the first cohort, a total of 456 serum specimens were collected from CHB
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patients at Zhongshan Hospital (Xiamen, China) and Xijing Hospital (Xi’an,
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China). All of these specimens were successfully subjected to HBV genome
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sequence analysis as previously described. The second group included 21
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CHB patients who had undergone more than 1 year of nucleos(t)ide analogue
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therapy (12 patients received entecavir and 9 patients received telbivudine).
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The baseline and EOT serum specimens were collected for a comparative
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analysis. The third group was derived from a phase 3 clinical trial of a hepatitis
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E virus (HEV) vaccine that was conducted between August 2007 and June
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2009 in Dongtai county, Jiangsu province, China. Serum samples were
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collected every year or every other year to assess the durability of immunity in
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two of the eleven towns (Quindong and Anfeng) where participants had been
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enrolled24. In 2013, we followed up 7507 participants in Anfeng; this time point 10
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Simultaneously,
the
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was 55 months after the first vaccine dose had been administered. All of the
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serum samples were screened for HBsAg, and 324 were positive. In addition,
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42 serum samples with low HBsAg level (less than 1,000 IU/mL) from patients
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with cirrhosis were collected from Xijing Hospital. All the samples were stored
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at -80℃ until genotyping using both GT-LFIA and sequencing. The study was
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approved by the medical ethics committee of the School of Public health,
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Xiamen University.
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Laboratory measurements
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The HBsAg levels were quantified with the Architect HBsAg assay (Abbott
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Laboratories, Abbott Park, IL, USA; detection range, 0.05–250 IU/mL). The
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serum HBV DNA levels were measured with the CobasTaqman HBV Kit
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(Roche Diagnostics, Indianapolis, IN, USA; lower limit of quantification, 12
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IU/mL). HBeAg and Anti-HBe were detected with an Architect assay (Abbott
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Laboratories). Aminotransferases were measured according to the local
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standard procedures at the time of sampling. The direct sequence genotyping
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method was determined by using whole genome or partial sequencing as
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described in a previous study25.
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Statistical analysis
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Parameters such as the HBsAg level were analyzed using descriptive
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statistics such as means and standard deviations, and the means were
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compared with an unpaired Student’s t-test. Differences between proportions
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were analyzed with the chi-square test. The statistical analysis was performed 11
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using SPSS (Statistical Package for the Social Sciences) ver. 17.0 software
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(SPSS Inc., Chicago, IL, USA). All statistical analyses were based on 2-tailed
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hypothesis tests with a significance level of p