Comparison of the results for three automated immunoassay systems in determining serum HBV markers

Seroepidemiology of Hepatitis B Virus Infection in Native and Immigrant Pregnant Women: A 20-Year Retrospective Study in Taiwan

Universal immunoprophylaxis against hepatitis B virus (HBV) is regarded as a key element to prevent perinatal HBV infection. The aim of the present study was to investigate the changes in the hepatitis B surface antigen (HBsAg)- and hepatitis B envelope antigen (HBeAg)-positive rates in native and immigrant pregnant women, to realize the impact of immigrants, and to identify any weaknesses 30 years after the implementation of hepatitis B vaccination in Taiwan. A total of 20,020 test results of HBsAg and HBeAg in pregnant women-2,915 (14.6%) immigrant women and 17,105 native Taiwanese-from 1996 to 2015 were analyzed for changes during this 20-year retrospective cohort study. Native Taiwanese have a higher HBsAg-positive rate than immigrant women (P < 0.001). However, the HBsAg-positive rates decreased by 0.6% per year among native women, but did not decrease significantly (only by 0.18% per year) among immigrant women. The overall HBsAg-positive rate remained at high levels, 4.8% in the year 2015. The HBeAg-positive rate decreased significantly, by 0.22% per year, in the total women as well as by 0.23% per year in the native women (all P < 0.001); by contrast, the HBeAg-positive rate in immigrants decreased at a slower rate (0.10% per year), without a significant decreasing trend (P = 0.300). Higher HBeAg (+)/HBsAg (+) rate was found for the immigrants than for the native women (P < 0.001). To quickly and effectively lower the risk of vertical transmission, new approaches combined with vaccination may be needed in the post-immunization era.

Clinical characteristics and association analysis of persistent low-level HBsAg expression in a physical examination population with HBV infection

Certain patients with hepatitis B virus (HBV) infection present with persistently low levels of serum hepatitis B surface antigen (HBsAg) and have been indicated to have low rates of HBV nucleic acid replication. To explore the serological and molecular epidemiological characteristics of HBV population with low-level HBsAg in the present study, associated serum markers and virologic genotype detection were performed accordingly. Determination of HBV markers was performed using a chemiluminescence immunoassay from which 2,544 out of 45,256 adults who underwent routine health examination were tested positive for HBsAg. HBV DNA was detected by real-time fluorescent quantitative PCR. The patients were divided into low-level and high-level groups, according to their HBsAg levels (cut-off value, 10 IU/ml). The prevalence and levels of HBsAg positivity and HBV DNA in patients with HBV infection were analyzed by age, sex, serological pattern and clinical type. The fibrosis status of patients with low-level HBsAg was assessed by determining the aspartate aminotransferase-to-platelet ratio (APRI), and sequencing was employed to determine serotypes and genotypes. HBV-infected patients with low-level HBsAg (<10 IU/ml) accounted for 15.41% of the 2,544 HBsAg-positive patients, and the prevalence of HBsAg positivity exhibited a tendency to increase with age. The male-to-female ratio was ~1.9:1, and the average age was 54.98±16.28 years among HBV-infected patients with low-level HBsAg. The major serological pattern and clinical types were HBsAg/antibody against hepatitis Be antigen (anti-HBe)/antibody against hepatitis B core antigen (anti-HBc)-positive (94.90%) and chronic asymptomatic (ASC) (97.95%), respectively. HBV DNA exhibited a low-level of replication and the prevalence of HBV DNA positivity assessed by the routine method and by the enrichment method was 27.74% (97/392) and 45.92% (180/392), respectively. No significant differences among the age groups were identified in the different HBsAg level groups (P>0.05). The prevalence of HBV DNA positivity was associated with HBsAg only in patients with serological pattern HBV-M2 (HBsAg/anti-HBe/anti-HBc-positive) in the low-level HBsAg group (odds ratio: 1.30; 95% CI: 1.15–1.47; P<0.05). The APRI had no association with age, HBsAg, HBV DNA level or liver function index in ASC patients in the low-level HBsAg group (P>0.05). The prevalence of the serotype adw and genotype B was 85.53 and 89.47%, respectively. Further improvement in the systematic study of populations with low-level HBsAg has important clinical and epidemiological significance for improving the detection of HBV serological markers, elucidating the mechanisms leading to low-level HBsAg, overcoming immune tolerance to eliminate HBV infection and preventing HBV transmission.

Clinical Characteristics and Correlation Analysis of Subjects with Chronic Hepatitis B Virus (HBV) Infection and Sustained Low Levels of Hepatitis B Surface Antigen (HBsAg)

BACKGROUND The aim of this study was to investigate the clinical characteristics of individuals with chronic hepatitis B virus (HBV) infection with persistent low levels of hepatitis B surface antigen (HBsAg) and to undertake a correlation analysis of the clinical characteristics. MATERIAL AND METHODS The study included 1,204 subjects with chronic HBV infection. Serum HBsAg, HBV envelope antigen (HBeAg), and HBV core antigen (HBcAg) levels were measured using the chemiluminescent microparticle immunoassay (CMIA) and the neutralization test. HBV DNA was measured using real-time fluorescence quantitative polymerase chain reaction (RT-FQ-PCR). RESULTS There were 1,023 subjects in the high-level HBsAg group (HBsAg level ≥10 IU/mL) and 181 subjects in the low-level HBsAg group (HBsAg level <10 IU/mL). In the low-level HBsAg group, the main serological pattern (93.37%) was HBsAg and HBeAg and HBcAg-positive (HBV-M2), and the asymptomatic carrier (ASC) status was 98.34%. The low-level HBsAg group had a lower HBV DNA-positive rate compared with the high-level HBsAg group (40.33% vs. 75.07%), with a normal distribution across all age groups (P>0.05). The low-level HBsAg group included an older age group. A low-level of HBsAg was positively correlated with a low level of replication of HBV DNA (r=0.452). CONCLUSIONS The findings of this study showed that individuals with chronic HBV infection and sustained low-levels of HBsAg were an older population and had a lower level of replicating HBV DNA when compared with individuals with high levels of HBsAg, and the majority (93.7%) were also HBsAg and HBeAg and HBcAg-positive.

Comparing Assay Performance of ELISA and Chemiluminescence Immunoassay in Detecting Antibodies to Hepatitis B Surface Antigen

INTRODUCTION

Antibodies to Hepatitis B surface Antigen (Anti-HBs) levels are measured as markers for immune response to vaccination and in decision making for post-exposure prophylaxis against Hepatitis-B. Several immunoassay formats are used to measure Anti-HBs, thus carrying the possibility of variation in measured levels between different assays. This study compares the performance of Chemiluminescence Immunoassay (CLIA) against Enzyme-linked Immunosorbent Assay (ELISA) in measuring Anti-HBs titer by looking into concordance between the two test reports.

AIM

To compare the agreement between ELISA and CLIA in measurement of Anti-HBs antibody titers.

MATERIALS AND METHODS

This prospective comparative study conducted at Kasturba Medical College, Manipal measured consecutive serum samples (69) sent for anti-HBs levels during May-June 2016 using both CLIA (Abbott Architect) and ELISA (Bio-Rad). Anti-HBs values of ≤10mIU/ml was considered as non-protective and >10mIU/ml as protective. The agreement between the tests in classifying the antibody titers as non-protective or protective was computed using Kappa coefficient, and the difference in individual titer values between the tests compared using Bland-Altman plot on SPSS (v.15).

RESULTS

Out of the 69 samples analysed, 18 samples (26.1%) were of health-care personnel and remaining of patients. Agreement between ELISA and CLIA in identifying the antibody titers as protective and non-protective were 96.5% and 90.9% respectively, resulting in an agreement of 0.84. The coefficient-of-variation of ELISA and CLIA were 74.5% and 113.1%, respectively. Three value based discordant results were noted; two samples deemed protective by ELISA were reported as non-protective by CLIA. One non-protective titer by ELISA was reported as protective by CLIA.

CONCLUSION

Analytical agreement is good between the two immunoassays. However there are some discrepancies in quantitative measurement. This may have been due the variation in the standard calibrators used in each assay. Though CLIA showed more variation in the values, it has the advantage of being automated test with low turn around time. Therefore, both the test methodologies can be reliably used in place of each other for detection of Anti- HBs titer.

The Performance of the Abbott i2000 for Measuring Serum Markers of Infectious Diseases

BACKGROUND

To date, there is a trend that the chemiluminescent microparticle immunoassays (CMIA) and electrochemiluminescence immunoassays (ECIA) technology gradually replacing the enzyme-linked immunosorbent assay (ELISA). But the performance such as the limit of quantitation (LOQ), precision, linear range of CMIA, or ECIA for serum markers of infectious diseases has rarely been reported.

METHODS

Using proficiency testing samples and standard materials, we confirmed the LOQ of the ELISA and the precision, linear range, LOQ, and instrument biases of the Abbott i2000 for eight serum markers. We used the Abbott i2000 and ELISAs to assess five HIV samples; the researchers were blinded to the true status of the samples.

RESULTS

For the Abbott i2000, the coefficients of variation (CV) for the low, medium, and high concentration samples ranged from 1.06 to 12.74%, which were less than the allowable error; the linear ranges of HBsAg and HBsAb were 0.66-304.11 IU/ml and 8.16-1205.9 mIU/ml, respectively. For the Abbott i2000, the LOQs of HBsAg, HBsAb, HBeAg, HBeAb, HBcAb, anti-HCV, anti-TP, and anti-HIV were 0.026 IU/ml, 4 mIU/ml, 0.14 NCU/ml, 0.56 NCU/ml, 0.99 NCU/ml, 0.5 NCU/ml, 8.8 mIU/ml, and 1.92 NCU/ml, respectively, and these values were 0.16 IU/ml, 6.97 mIU/ml, 1.16 NCU/ml, 1.63 NCU/ml, 1.79 NCU/ml, 1.03 NCU/ml, 8.33 mIU/ml, and 1.3 NCU/ml, respectively, for the ELISA. When five HIV samples were blindly assessed, two cases were missed by the Abbott i2000 and the ELISA results were consistent with the expected results.

CONCLUSIONS

The Abbott i2000 performed significantly better than the ELISA on HBV and HCV screening; however, for anti-TP and anti-HIV, the ELISA remained the preferred method.

Update on hepatitis B and C virus diagnosis

Viral hepatitis B and C virus (HBV and HCV) are responsible for the most of chronic liver disease worldwide and are transmitted by parenteral route, sexual and vertical transmission. One important measure to reduce the burden of these infections is the diagnosis of acute and chronic cases of HBV and HCV. In order to provide an effective diagnosis and monitoring of antiviral treatment, it is important to choose sensitive, rapid, inexpensive, and robust analytical methods. Primary diagnosis of HBV and HCV infection is made by using serological tests for detecting antigens and antibodies against these viruses. In order to confirm primary diagnosis, to quantify viral load, to determine genotypes and resistance mutants for antiviral treatment, qualitative and quantitative molecular tests are used. In this manuscript, we review the current serological and molecular methods for the diagnosis of hepatitis B and C.

Brief communication: comparison the diagnostic performance of four HBsAg ELISA kits

BACKGROUND

Comparison of diagnostic efficiency of four ELISA kits for determining HBsAg.

METHODS

Collecting 348 serum samples from clinical laboratory of Renmin Hospital of Wuhan University without specific gender and age requirements, determining HBsAg by the four ELISA kits, simultaneously. Confirmatory test was carried out when the initial results are positive.

RESULTS

329 out of 348 samples results were consistent (94.5%), 152 out of 329 were positive, and 177 out of 329 were negative, and all the positive results can be confirmed; 19 samples were not consistent (5.5%), and only 1 sample was confirmed by the confirmatory test. After calculation, the diagnostic efficiencies of the four ELISA kits (Beijing Wantai, Xiamen Xinchuang, Zhuhai Lizhu, and Shanghai Kehua) were 98.6%, 98.0%, 99.7%, and 97.4%, respectively, the sensitivities were 100%, 99.4%, 99.4%, and 100%, respectively, the specificities were 97.5%, 96.9%, 100%, and 95.4%, respectively, the false positive rates were 2.5%, 3.1%, 0, and 4.6%, respectively, and the false negative rates were 0, 0.6%, 0.6%, and 0, respectively. All the initial absorbencies of the false positive samples were less than 1.0.

CONCLUSION

The diagnostic efficiency of Lizhu is the highest, while Kehua is the lowest. False positive or false negative results would take place in any of the kits, an HBsAg confirmatory test is essential for initially positive samples, especially with absorbance <1.0, because it can exclude most false positives.

Seroepidemiology of hepatitis B virus infection among adults in Singapore: a 12-year review

We undertook a national hepatitis B seroprevalence study to assess the seroprevalence of hepatitis B virus (HBV) markers in the adult population in Singapore in 2010 and make comparisons with the seroprevalence in 1998 and 2004. The study involved residual sera from national health surveys conducted every six years since 1998. The tests for HBV markers were carried out using commercial chemiluminescent microparticle immunoassay. In 2010, the prevalence of hepatitis B surface antigen (HBsAg) among 3293 Singapore residents aged 18-79 years was 3.6% (95% confidence interval [CI] 2.9-4.2%). Hepatitis B e antigen (HBeAg) was detected in 4.2% of those who were HBsAg positive. About 22.5% (95% CI 21.1-23.9%) were positive for antibody to hepatitis B core antigen (anti-HBc). The overall population immunity to HBV, as determined by antibody to hepatitis B surface antigen (anti-HBs)≥ 10 mIU/mL, was 43.9% (95% CI 42.2-45.6%). Among young adults below 30 years of age, HBsAg prevalence (1.1%) was half that in 1998 and 2004, and in those positive for HBsAg, none was positive for HBeAg in 2010, compared to 20.8% in 1998 and 15.8% in 2004. In this age group, anti-HBc prevalence also decreased significantly from 22.1% in 2004 to 4.4% in 2010, while anti-HBs (≥ 10 mIU/mL) prevalence increased significantly from 27.9% in 1998 to 43.3% in 2010 (p<0.001). The national childhood HBV immunisation and catch-up programmes implemented in 1987 and 2001-2004, respectively, had a significant impact in reducing HBV infection and in raising the immunity of the adult population 18-29 years of age.

Evaluation of the performance of four methods for detection of hepatitis B surface antigen and their application for testing 116,455 specimens

Hepatitis B surface antigen (HBsAg) is a crucial serum marker for the diagnosis of hepatitis B virus (HBV) infection. It is imperative to compare test results from different detection methods based on different principles. Four methods, chemiluminescent microparticle immunoassay (CMIA), electrochemiluminescent immunoassay (ECLIA), enzyme-linked immunosorbent assay (ELISA) and golden immunochromato-graphic assay (GICA) were applied to test the HBsAg level in 250 specimens. According to the EP12-A2 and EP15-A2 documents from Clinical and Laboratory Standards Institute (CLSI), the concentration at which repeated results are 50% positive (C50) of HBsAg detected by CMIA, ECLIA, ELISA and GICA was 0.05, 0.08, 0.15 and 15.0IU/ml, respectively. When the detection concentration of HBsAg was 0.5IU/ml, the imprecision degree of CMIA, ECLIA and ELISA was 8.1%, 5.9% and 14.9% respectively. When detecting high HBsAg level (≥20.0IU/ml) and HBsAg negative specimens, the consistency of the four methods was high, while for the low level (0.05-20.0IU/ml), the consistency was poor (except for the CMIA and ECLIA, P<0.05). When evaluation of the four methods in qualitative diagnosis of HBsAg level in the 116,455 specimens, there was no significant discrepancy among CMIA, CMIA and ECLIA, however, GICA was significantly different from the other 3 methods. Compared with CMIA, the false negative rate of ECLIA, ELISA and GICA was 0.2%, 1.3% and 12.3% respectively. In conclusion, GICA was only suitable for the preliminary screening of HBsAg positive individuals and ELISA can be applied to the qualitative diagnosis of HBsAg. Both CMIA and ECLIA were suitable for the quantitative determination of HBsAg.

Establishment and application of hepatitis B virus persistent replication model in IFNAR(-/-) mouse

The type I interferon and IFNAR play an important role in hepatitis B virus (HBV) infection and anti-HBV therapy. However, its mechanism of action is still poorly understood. To gain more insights into the role of type I interferon and type I interferon receptor (IFNAR) in HBV infection, we established an HBV persistent replication IFNAR knockout (IFNAR(-/-)) mouse model and preliminarily applied this model. At first, the progeny of IFNAR(-/-) mouse was reproduced. Then hydrodynamic injection with pAAV/HBV1.2 plasmid was conducted to establish the persistent HBV replication IFNAR(-/-) mouse model. At last, we applied this model to evaluate the effect of nucleoside analogues entecavir (ETV) on HBV replication. It was found that there was no difference in the serum HBsAg and HBeAg levels and HBcAg expression in the liver tissue between the ETV treated groups and normal saline (NS) treated group, but the serum HBV DNA levels were significantly suppressed 10, 25, 40 and 55 days after the ETV treatment [P=0.035, P=0.00, P=0.149 and P=0.084, IFNAR knockout (KO) control group vs. C57BL/6 ETV groups, respectively; P=0.081, P=0.001, P=0.243 and P=0.147, IFNAR KO control group vs. IFNAR KO ETV groups, respectively]. Interestingly, there was no difference in serum HBV DNA levels between the ETV treated IFNAR(-/-) and C57BL/6 mice. This result suggests that HBV suppression during ETV treatments doesn't depend on type I interferon and IFNAR. Collectively, persistent HBV replication IFNAR(-/-) mouse model that we established is a useful and convenient tool to detect the function of the type I interferon and IFNAR in HBV infection and anti-HBV treatments.

Detection of infections with hepatitis B virus, hepatitis C virus, and human immunodeficiency virus by analyses of dried blood spots--performance characteristics of the ARCHITECT system and two commercial assays for nucleic acid amplification

BACKGROUND

Nowadays, dried blood spots (DBS) are primarily used to obtain diagnostic access to risk collectives such as intravenous drug users, who are prone to infections with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Before DBS analyses can be used in this diagnostic context, however, a comprehensive evaluation of its performance characteristics must be conducted. To the best of our knowledge, the current study presents for the first time such essential data for the Abbott ARCHITECT system, which is currently the worldwide leading platform in this field of infection diagnostics.

METHODS

The investigation comprised 1,762 paired serum/DBS samples and a total of 3,524 determinations with the Abbott ARCHITECT HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24-antigen/anti-HIV 1/2 assays as well as with the artus HBV LC PCR and VERSANT HCV RNA qualitative (TMA) tests.

RESULTS

In the context of DBS testing, a specificity of 100% was recorded for the seven serological and molecular biological assays. The analytical sensitivity of HBsAg, anti-HBc, anti-HBs, anti-HCV, HIV-1-p24-antigen/anti-HIV 1/2, HBV DNA, and HCV RNA detections in DBS eluates was 98.6%, 97.1%, 97.5%, 97.8%, 100%, 93%, and 100%, respectively.

DISCUSSION/CONCLUSIONS

The results obtained indicate that it is today possible to reliably detect HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24 antigen/anti-HIV 1/2 with state-of-the-art analytical systems such as the Abbott ARCHITECT in DBS eluates even when a comparatively high elution volume of 1,000 μl is used. They also provide evidence for the inherent analytical limits of DBS testing, which primarily concern the anti-HBc/anti-HBs system for individuals with HIV infections and nucleic acid tests with relatively low analytical sensitivity.

Detection of infections with hepatitis B virus, hepatitis C virus, and human immunodeficiency virus by analyses of dried blood spots--performance characteristics of the ARCHITECT system and two commercial assays for nucleic acid amplification

BACKGROUND

Nowadays, dried blood spots (DBS) are primarily used to obtain diagnostic access to risk collectives such as intravenous drug users, who are prone to infections with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Before DBS analyses can be used in this diagnostic context, however, a comprehensive evaluation of its performance characteristics must be conducted. To the best of our knowledge, the current study presents for the first time such essential data for the Abbott ARCHITECT system, which is currently the worldwide leading platform in this field of infection diagnostics.

METHODS

The investigation comprised 1,762 paired serum/DBS samples and a total of 3,524 determinations with the Abbott ARCHITECT HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24-antigen/anti-HIV 1/2 assays as well as with the artus HBV LC PCR and VERSANT HCV RNA qualitative (TMA) tests.

RESULTS

In the context of DBS testing, a specificity of 100% was recorded for the seven serological and molecular biological assays. The analytical sensitivity of HBsAg, anti-HBc, anti-HBs, anti-HCV, HIV-1-p24-antigen/anti-HIV 1/2, HBV DNA, and HCV RNA detections in DBS eluates was 98.6%, 97.1%, 97.5%, 97.8%, 100%, 93%, and 100%, respectively.

DISCUSSION/CONCLUSIONS

The results obtained indicate that it is today possible to reliably detect HBsAg, anti-HBc, anti-HBs, anti-HCV and HIV-1-p24 antigen/anti-HIV 1/2 with state-of-the-art analytical systems such as the Abbott ARCHITECT in DBS eluates even when a comparatively high elution volume of 1,000 μl is used. They also provide evidence for the inherent analytical limits of DBS testing, which primarily concern the anti-HBc/anti-HBs system for individuals with HIV infections and nucleic acid tests with relatively low analytical sensitivity.

Comparison of two immunoassays for determining hepatitis B virus serum markers

BACKGROUND

To evaluate and compare the detection efficacy of serum hepatitis B virus (HBV) markers by two immunoassays: electrochemiluminescence immunoassay (ECLIA) and enzyme-linked immunosorbent assay (ELISA).

METHODS

ECLIA and ELISA were used to analyze 359 serum samples, including 64 HBsAg/anti-HBs coexistence serological pattern samples (samples positive for both HBsAg and anti-HBs), 24 HBeAg/anti-HBe coexistence serological pattern samples (samples positive for both HBeAg and anti-HBe), and 271 normal serological pattern samples (negative for either of the combinations).

RESULTS

In the normal serological pattern samples, the concordance rates of the two methods in detecting serum HBV markers were as follows: 97.05% for HBsAg, 92.62% for anti-HBs, 100% for HBeAg, 76.75% for anti-HBe, and 58.67% for anti-HBc. The differences in the qualitative criteria for anti-HBc and anti-HBe were primarily responsible for the discrepancy between the two methods (κ-values of 0.657 and 0.253, respectively). Most weak positive results, determined by ECLIA, were negative determined by ELISA, whereas the results of HBsAg, anti-HBs, and HBeAg detection were generally consistent. In the HBsAg/anti-HBs coexistence serological pattern samples, the concordance rates of HBsAg and anti-HBs detection were 98.44% and 34.38%, respectively. The positive rate of ELISA does not vary as the COI (cut-off index) varies which was determined by ECLIA; in the HBeAg/anti-HBe coexistence serological pattern samples, the concordance rates of HBeAg and anti-HBe detection were 45.83% and 79.17%, respectively. Most weak positive results, determined by ECLIA, were negative when determined by ELISA.

CONCLUSION

The discrepancies between the two assays in normal serological patterns samples and HBeAg/anti-HBe coexistence serological pattern samples were mostly due to the different sensitivity of the two assays, but for the HBsAg/anti-HBs coexistence serological pattern samples, the discrepancy was not caused by the different sensitivity. It is the difference in determining anti-HBs which led to the discrepancy.

Synergetic chemiluminescence and label-free dual detection for developing a hepatitis protein array

A dual detection system for protein arrays is presented that combines label-free detection by optical interference with chemiluminescence. A planar protein array that targets hepatitis B surface antigen is developed. Surface densities for individual antibody spots are quantitated using optical interference prior to use. Target binding (10 ng/ml) is detected label-free. Target binding (1 ng/ml) is detected by both optical interference and chemiluminescence with the inclusion of secondary antibodies. Binding results using both methods are found to be directly proportion to the capture probe density measured initially. The dual detection system provides the analytical utility of optical interference detection with the established clinical utility of chemiluminescence detection.

Changing Seroprevalence of Hepatitis B Virus Markers of Adults in Singapore

Introduction: We presented the findings from 2 seroprevalence studies conducted 6 years apart, so as to determine changes in the hepatitis B surface antigen (HBsAg) positivity rate and immunity to hepatitis B virus (HBV) among Singapore residents aged 18 to 69 years, and to assess the impact of a 4-year catch-up hepatitis B immunisation programme for adolescents and young adults launched in 2001. Materials and Methods: Two hepatitis B seroprevalence studies (HBSS) were conducted in 1999 and 2005 based on stored blood samples collected from 4698 participants aged 18 to 69 years during the national health survey (NHS) 1998 and from 3460 participants during the NHS 2004, respectively. Serology for HBsAg, hepatitis B e antigen (HBeAg) and antibody to HBsAg (anti-HBs) were tested by enzyme immunoassay in HBSS 1999 and electrochemiluminescence in HBSS 2005. Results: The overall age-standardised prevalence of HBsAg among Singapore residents aged 18 to 69 years decreased significantly from 4.0% in HBSS 1999 to 2.8% in HBSS 2005 (P = 0.002). The age-standardised prevalence of HBsAg in males (4.9% in 1999) and Chinese (4.7% in 1999) both decreased significantly to 2.7% and 2.8%, respectively in 2005. The overall age-standardised population immunity to HBV (anti-HBs >10mIU/ml) increased from 39.7% in 1999 to 42.1% in 2005 (P = 0.019). In particular, the age-specific prevalence of anti-HBs showed a significant increase among those in the age group of 18 to 29 years from 27.9% in 1999 to 41.7% in 2005 (P <0.001) and among those in the age group of 30 to 39 years from 39.9% in 1999 to 44.7% in 2005 (P = 0.021). Conclusion: There was an overall decline in the HBsAg positivity rate as well as an overall increase in population immunity to HBV. Following the 4-year catch-up immunisation programme, there was a significant increase in the immunity to HBV infection in the younger population aged 18 to 29 years. Keywords: Adult infection, Catch-up immunisation, Epidemiological trends

Detection of hepatitis B virus markers using a biosensor based on imaging ellipsometry

A biosensor based on imaging ellipsometry (BIE) has been developed and validated in 169 patients for detecting five markers of hepatitis B virus (HBV) infection. The methodology has been established to pave the way for clinical diagnosis, including ligand screening, determination of the sensitivity, set-up of cut-off values (CoVs) and comparison with other clinical methods. A matrix assay method was established for ligand screening. The CoVs of HBV markers were derived with the help of receiver operating characteristic curves. Enzyme-linked immunosorbent assay (ELISA) was the reference method. Ligands with high bioactivity were selected and sensitivities of 1 ng/mL and 1 IU/mL for hepatitis B surface antigen (HBsAg) and surface antibody (anti-HBs) were obtained respectively. The CoVs of HBsAg, anti-HBs, hepatitis B e antigen, hepatitis B e antibody and core antibody were as follows: 15%, 18%, 15%, 20% and 15%, respectively, which were the percentages over the values of corresponding ligand controls. BIE can simultaneously detect up to five markers within 1 h with results in acceptable agreement with ELISA, and thus shows a potential for diagnosing hepatitis B with high throughput.

Monoclonal antibody against non-dominant epitopes of HBV e Ag was raised by antigen–antibody co-immunization

Detection of hepatitis B e antigen (HBeAg) in the sera of individuals infected with hepatitis B virus (HBV) can indicate both a high infectivity of the disease and a poor prognosis of disease treatment. Most of monoclonal antibodies raised against HBV e proteins interact with immuno-dominant epitopes, such as HBeAg-beta. In order to raise antibodies against non-dominant epitopes of HBV e protein, in this study, mice were immunized with both recombinant HBeAg (rHBeAg) and an anti-HBeAg antibody (EWB) recognizing a dominant antigenic epitope of HBeAg (HBeAg-beta epitope). With this strategy, we successfully selected two monoclonal antibodies, S-29-3 and S-72-3. Both S-29-3 and S-72-3 bind to recombinant HBeAg with a high affinity. The epitope mapping assay determined that the S-73-2 recognizes the N-terminal of HBeAg (1-118 aa) and the S-29-3 recognizes the C-terminal of HBeAg (91-149 aa). Further experiment showed that these two antibodies could be formed a pair-Abs that is used in detecting native HBeAg from the sera of HBV patients. The conclusion is that the developed method is useful to raise mAb against non-dominant epitopes in given Ag.