Evaluation of two new automated assays for hepatitis B virus surface antigen (HBsAg) detection: IMMULITE HBsAg and IMMULITE 2000 HBsAg

Cortisol and DHEA-S levels in pregnant women with severe anxiety

BACKGROUND

A complex interaction between cortisol and dehydroepiandrosterone-sulphate (DHEA-S) is crucial in the stress system balance; several studies have reported increased cortisol levels during chronic stress and a weak counter-regulation by DHEA-S. During pregnancy, scarce information about this system is available, although cortisol and DHEA-S play an important role in the initiation and acceleration of labor. We conducted the present study in order to determine both cortisol and DHEA-S levels during the last trimester of pregnancy in patients exhibiting severe anxiety.

METHODS

Pregnant women during the 3rd trimester of pregnancy were evaluated by using the self-reported version of the Hamilton Anxiety Rating Scale (HARS). According to the scores obtained from the psychometric scale, participants were divided into two groups: 1) patients exhibiting a cutoff score > 15 were considered with severe anxiety (ANX) (n = 101), and control pregnant subjects (CTRL) (n = 44) with a cutoff score < 5. Morning cortisol, DHEA-S and Cortisol/DHEA-S index were measured in all participants. Comparisons between groups were performed; additionally, correlations between clinical variables, biochemical data and HARS were calculated.

RESULTS

Cortisol levels were significantly higher in the ANX group (p < 0.001), whereas those of DHEA-S were significantly lower in the same group (p < 0.01) when compared to healthy pregnant subjects. An increased cortisol/DHEA-S index was observed in the ANX group (p < 0.05). A significant association between cortisol and HARS scores (p = 0.03), was observed even after adjusting by gestational weeks (p = 0.004).

CONCLUSIONS

Our data support that the cortisol/DHEA-S index is higher in pregnant women with high anxiety levels as compared with healthy pregnant women.

Quantification of hepatitis B surface antigen and E antigen: correlation between Elecsys and architect assays

Quantification of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) and their change model during treatment are emerging as a useful tool for assessing the outcome of hepatitis B virus (HBV) infection and predicting the efficacy of antiviral therapy. The aim of this study was to compare the performance of the Elecsys and Architect assays for HBsAg and HBeAg quantification. Quantification of HBsAg and HBeAg, determined by these two assays, were assessed in 1292 sera from patients with chronic hepatitis B(CHB). HBeAg quantification in serum was performed by calibrating the results through HBeAg Paul-Ehrlich international (PEI) reference standard. The HBV genotype was determined by direct sequencing and phylogenetic analysis. Of 1292 samples, the distribution of genotype was 514 (39.78%) genotype B, 776 (60.06%) genotype C, 2 (0.16%) genotype D. The results of HBsAg and HBeAg quantification between the Architect and Elecsys assays were significantly correlated (HBsAg: r = 0.939; HBeAg: r = 0.987), independent of HBV genotype and treatment phase. The mean differences between the two methods (the log10 [Elecsys] - the log10 [Architect]) were 0.075 log10  IU/mL and -0.149 log10 PE IU/mL in quantifying HBsAg and HBeAg, respectively. This study demonstrates a high correlation between the Elecsys and the Architect assays in quantifying HBsAg and HBeAg, regardless of HBV genotype. Both the two assays can be used to monitor the HBsAg and HBeAg levels in patients with chronic hepatitis B.

Occult hepatitis B virus infection among Egyptian blood donors

AIM

To identify blood donors with occult hepatitis B virus (HBV) infection (OBI) to promote safe blood donation.

METHODS

Descriptive cross sectional study was conducted on 3167 blood donors negative for hepatitis B surface antigen (HBsAg), hepatitis C antibody (HCV Ab) and human immunodeficiency virus Ab. They were subjected to the detection of alanine aminotransferase (ALT) and aspartate transaminase (AST) and screening for anti-HBV core antibodies (total) by two different techniques; [Monoliza antibodies to hepatitis B core (Anti-HBc) Plus-Bio-Rad] and (ARC-HBc total-ABBOT). Positive samples were subjected to quantitative detection of antibodies to hepatitis B surface (anti-HBs) (ETI-AB-AUK-3, Dia Sorin-Italy). Serum anti-HBs titers > 10 IU/L was considered positive. Quantitative HBV DNA by real time polymerase chain reaction (PCR) (QIAGEN-Germany) with 3.8 IU/mL detection limit was estimated for blood units with negative serum anti-HBs and also for 32 whose anti-HBs serum titers were > 1000 IU/L. Also, 265 recipients were included, 34 of whom were followed up for 3-6 mo. Recipients were investigated for ALT and AST, HBV serological markers: HBsAg (ETI-MAK-4, Dia Sorin-Italy), anti-HBc, quantitative detection of anti-HBs and HBV-DNA.

RESULTS

525/3167 (16.6%) of blood units were positive for total anti-HBc, 64% of those were anti-HBs positive. Confirmation by ARCHITECT anti-HBc assay were carried out for 498/525 anti-HBc positive samples, where 451 (90.6%) confirmed positive. Reactivity for anti-HBc was considered confirmed only if two positive results were obtained for each sample, giving an overall prevalence of 451/3167 (14.2%) for total anti-HBc. HBV DNA was quantified by real time PCR in 52/303 (17.2%) of anti-HBc positive blood donors (viral load range: 5 to 3.5 x 10(5) IU/mL) with a median of 200 IU/mL (mean: 1.8 x 10(4) ± 5.1 x 10(4) IU/mL). Anti-HBc was the only marker in 68.6% of donors. Univariate and multivariate logistic analysis for identifying risk factors associated with anti-HBc and HBV-DNA positivity among blood donors showed that age above thirty and marriage were the most significant risk factors for prediction of anti-HBc positivity with AOR 1.8 (1.4-2.4) and 1.4 (1.0-1.9) respectively. Other risk factors as gender, history of blood transfusion, diabetes mellitus, frequent injections, tattooing, previous surgery, hospitalization, Bilharziasis or positive family history of HBV or HCV infections were not found to be associated with positive anti-HBc antibodies. Among anti-HBc positive blood donors, age below thirty was the most significant risk factor for prediction of HBV-DNA positivity with AOR 3.8 (1.8-7.9). According to HBV-DNA concentration, positive samples were divided in two groups; group one with HBV-DNA ≥ 200 IU/mL (n = 27) and group two with HBV-DNA < 200 IU/mL (n = 26). No significant difference was detected between both groups as regards mean age, gender, liver enzymes or HBV markers. Serological profiles of all followed up blood recipients showed that, all were negative for the studied HBV markers. Also, HBV DNA was not detected among studied recipients, none developed post-transfusion hepatitis (PTH) and the clinical outcome was good.

CONCLUSION

OBI is prevalent among blood donors. Nucleic acid amplification/HBV anti core screening should be considered for high risk recipients to eliminate risk of unsafe blood donation.

[Evaluation of HBs Ag, HCV and HIV Ag-Ab Assays using Bio-Rad Elite Microplate Analyzer.]

BACKGROUND

In this study, we evaluated the performance of Elite microplate analyzer (Bio-Rad Laboratories, France) and the related assays (ULTRA line) for the detection of hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV).

METHODS

Seroconversion panels, HBsAg positive/HBsAg negative (n=99/n=1,422), anti-HCV positive/negative (n=97/n=1,670), and anti-HIV positive/negative (n=112/n=1,704) samples were used to evaluate the performance of Monolisa HBsAg ULTRA, Monolisa HCV Ag-Ab ULTRA, and Genscreen ULTRA HIV Ag-Ab, respectively. The agreement of Elite microplate analyzer with CODA analyzer (Bio-Rad Laboratories, CA, USA) was also evaluated.

RESULTS

The detection limit of Monolisa HBsAg ULTRA was 0.034 IU/mL. For Monolisa HBsAg ULTRA, Monolisa HCV Ag-Ab ULTRA, and Genscreen ULTRA HIV Ag-Ab, diagnostic sensitivities were all 100%, diagnostic specificities were 100%, 99.8% and 99.9%, and total CVs (coefficients of variation) were 13.8-17.5%, 3.4-5.2%, and 7.5-9.5%, respectively. The agreement of Elite microplate analyzer with CODA analyzer was 99.5%.

CONCLUSIONS

The performance of Elite microplate analyzer and the related assays on analytical sensitivity, precision, early detection, diagnostic sensitivity and specificity was all adequate for a mass screening. However, further large multi-center studies should be performed to validate our results.

Pre- and post-transfusion testing for hepatitis B virus surface antigen and antibody in blood recipients: a single-institution experience in an area of high endemicity

Background

Hepatitis B remains the most common transfusion-transmitted viral infection. We explored the current status of pre-transfusion screening and post-transfusion follow-up testing for hepatitis B virus (HBV) surface antigen (HBsAg) and antibodies (anti-HBs) in blood recipients from an area of high HBV endemicity.

Methods

A total of 7,780 blood recipients were transfused with at least 1 unit of blood component at a single university hospital in Korea between January 2006 and December 2009. Their medical records were reviewed, and their demographic and transfusion-related data were analyzed.

Results

Pre-transfusion HBsAg and anti-HBs levels were tested in 77.6% (6,037/7,780) of the recipients. The results varied widely according to recipient age. In all, 32.8% (1,982/6,037) of the recipients who were tested had dual negative pre-transfusion results for HBsAg and anti-HBs and, therefore, were at increased risk of HBV transmission. Post-transfusion follow-up testing for HBsAg and/or anti-HBs was performed in 22% (436/1,982) of the increased-risk group.

Conclusions

Our data show that current transfusion-related laboratory testing practice is not sufficient to properly investigate possible post-transfusion infections. Routine laboratory tests, including HBsAg and anti-HBs, should be recommended in transfusion guidelines.

Reducing the risk of hepatitis B virus transfusion-transmitted infection

Before 1970, approximately 6% of multi-transfused recipients acquired a transfusion-transmitted Hepatitis B virus (HBV) infection. The safety improvements since then have been tremendous. From a level of a few infections per 1000 donations, the risk today, depending on the screening algorithm and additional measurements performed, has decreased to around 1:500,000 to 1:1,000,000, an improvement greater than 1000-fold compared to 50 years ago. This enormous gain in safety has been achieved through many factors, including development of increasingly more sensitive Hepatitis B antigen (HBsAg) assays; the adoption in some countries of hepatitis B core antibody (anti-HBc) screening; an improved donor selection procedure; HBV vaccination programs; and finally the introduction of HBV nucleic acid testing (NAT). Because there is a tendency in transfusion medicine to add one safety measure on top of another to approach the ultimate goal of zero risks, costs become increasingly a matter of debate. It is obvious that any new measure in addition to existing methods or measures will have very poor cost effectiveness. Therefore each country needs to perform its own calculation based on the country’s own epidemiology, resources, political and public awareness of the risks, in order to choose the correct and most cost-efficient measures. Ideally, each country would make decisions regarding implementation of additional blood safety measures in the context of both the perceived benefit and the allocation of overall health care resources.

[Comparison of nine different qualitative HBsAg assay kits]

BACKGROUND

Qualitative hepatitis B surface antigen (HBsAg) assay kits are still commonly used in Korea where hepatitis B virus (HBV) infection is endemic. The accurate determination of HBsAg plays a crucial role in the diagnosis and prevention of HBV infection, especially in endemic areas. The aim of this study was to compare the detection sensitivities of 9 qualitative HBsAg assay kits.

METHODS

Seven pooled sera with HBsAg concentration ranging from 0.14 IU/mL to 29.96 IU/mL were prepared. The HBsAg concentration of each pooled serum was determined by a quantitative HBsAg assay, Architect HBsAg (Abbott Laboratories, Ireland). The fully automated immunoassay kits included Elecsys HBsAg (Roche Diagnostics, Germany) and Immulite 2000 HBsAg (DPC, USA) and the rapid tests included 5 immunochromatographic assay (ICA) kits and 2 reverse passive hemagglutination assay (RPHA) kits.

RESULTS

Elecsys HBsAg (Roche Diagnostics) showed positive result in pooled serum with HBsAg concentration of 0.14 IU/mL, but Immulite 2000 HBsAg (DPC) showed negative result in the same concentration. Although ICA kits showed variable results among different assay kits, all of them showed negative results in pooled sera with HBsAg concentration of < or = 1.89 IU/mL. Two RPHA kits showed negative results in pooled sera with HBsAg concentration of < or = 7.98 IU/mL.

CONCLUSIONS

Although ICAs were more sensitive than RPHAs, they had variable sensitivities for HBsAg and were less sensitive than the automated immunoassay kits. Therefore, ICAs and RPHAs should be used with caution in the screening tests for HBsAg and their sensitivities need to be improved.

The underlying mechanisms for the "isolated positivity for the hepatitis B surface antigen (HBsAg)" serological profile

During HBV infection, four structural antigen/antibody systems are observed: hepatitis B surface antigen (HBsAg) and its antibody (anti-HBs); the pre-S antigens associated with HBsAg particles and their antibodies; the particulate nucleocapsid antigen (HBcAg) and anti-HBc; and an antigen structurally related to HBcAg, namely HBeAg and its antibody (anti-HBe). Through the examination of this antigen-antibodies system, hepatitis B infection is diagnosed and the course of the disorder may be observed. Isolated HBsAg seropositivity is a peculiar serological pattern in HBV infection observed some times in routine laboratory. In most cases is not clear how this profile should be interpreted neither its significance. This pattern, however, may be associated with some clinical and laboratorial situations of great relevance, some of which will be addressed in this article.

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

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.

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

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.

Transfusion-transmitted hepatitis B virus infection

Hepatitis B virus (HBV) remains a major risk of transfusion-transmitted infection due to the pre-seroconversion window period (WP), infection with immunovariant viruses, and with occult carriage of HBV infection (OBI). Reduction of HBV residual risk depends upon developing more sensitive HBV surface antigen (HBsAg) tests, adopting anti-HBc screening when appropriate, and implementing HBV nucleic acid testing (NAT), either in minipools or more efficiently in individual samples. HBV NAT combines the ability to significantly reduce the window period and to detect occult HBV carriage substantiating decades of clinical observation that HBsAg-negative/anti-HBc-positive blood could transmit HBV. Clinical observations suggest limited transmission rate of occult HBV compared to WP. Low transmission rate might be related to low viral load observed in OBIs or to the presence of mutants associated with occult carriage. OBIs carrying detectable anti-HBs ( approximately 50%) are essentially not infectious by transfusion. However, recent data suggest that the neutralizing capacity of low anti-HBs may be inefficient when overcome by exposure to high viral load. Anti-HBc blood units without detectable anti-HBs appear moderately infectious except in immunocompromised recipients. Immunodeficient elderly and patients receiving immunosuppressive treatments may be susceptible to infection with lower infectious dose even in the presence of anti-HBs. The immune status of blood recipients should be taken into consideration when investigating "post-transfusion" HBV infection. Pre-transfusion testing and post-transfusion long-term follow-up of recipients, and molecular analysis of the virus infecting both donor and recipient are critical to definitively incriminate transfusion in the transmission of HBV.

Diagnosis and management of chronic viral hepatitis: antigens, antibodies and viral genomes

Virological tools, including serological and molecular tools, are needed to diagnose chronic hepatitis B and C infections. They may also be useful to establish their prognosis, but they have found their principal application in guiding treatment decisions and assessing the virological responses to therapy. The goal of chronic hepatitis B therapy is to prevent progression of liver disease. This is achieved if HBV replication is durably abolished or significantly reduced. In HBeAg-positive patients, HBeAg clearance followed by the HBe seroconversion phase can be achieved. In HBeAg-negative patients, long-term antiviral suppression of viral replication is needed. The loss of HBsAg, eventually associated with an HBs seroconversion, is the most desirable endpoint of therapy but is rarely achieved. The efficacy endpoint of chronic hepatitis C treatment is the sustained virological response, defined by an undetectable HCV RNA in serum with a sensitive assay 24 weeks after the end of treatment. The HCV genotype and on-treatment viral kinetics can be used to tailor treatment dosages and duration.

[Meta-analysis for the pooled sensitivity and specificity of hepatitis B surface antigen rapid tests]

BACKGROUND

Although hepatitis B surface antigen (HBsAg) rapid test based on immunochromatographic assay (ICA) is now widely used, the test has not been evaluated sufficiently enough to validate its performance. Thus, it is important to summarize the clinical performance of the test kits. In this study, we performed meta-analysis for the performance of the HBsAg rapid tests.

METHODS

PubMed database was searched using keywords about the accuracy of diagnostic tests for hepatitis B virus (HBV) infection. Two investigators assessed methodological quality utilizing standards for reporting of diagnostic accuracy studies (STARD) checklist. After performing a heterogeneity test, we obtained pooled sensitivity and specificity. Positive and negative predictive values (PPV and NPV) were simulated according to HBV prevalence.

RESULTS

A total of 38 studies was selected from 10 papers. The quality scores ranged from 3 to 13 (median, 8). Kappa value was good (0.85). The performance of the 38 studies was heterogeneous. When 33 studies with better quality from 7 papers were re-selected, the pooled sensitivity and specificity were 98.07% (95% confidence interval, CI: 97.67-98.47%) and 99.56% (95% CI: 99.21-99.91%), respectively. With an HBV prevalence of 5%, PPV and NPV were predicted to be 92.14% and 99.90%, respectively.

CONCLUSIONS

In view of high HBV prevalence in Korea, it is thought that the HBsAg rapid test can be used for HBV screening in small-sized laboratories or for epidemiologic studies. This study should be helpful in establishing a guideline for the proper performance evaluation of the HBsAg rapid tests.

Molecular targets for diagnostics and therapeutics of severe acute respiratory syndrome (SARS-CoV)

PURPOSE

The large number of deaths in a short period of time due to the spread of severe acute respiratory syndrome (SARS) infection led to the unparalleled collaborative efforts world wide to determine and characterize the new coronavirus (SARS-CoV). The full genome sequence was determined within weeks of the first outbreak by the Canadian group with international collaboration. As per the World Health Organization (WHO), the continual lack of a rapid laboratory test to aid the early diagnosis of suspected cases of SARS makes this area a priority for future research. To prevent deaths in the future, early diagnosis and therapy of this infectious disease is of paramount importance.

METHODS

This review describes the specific molecular targets for diagnostics and therapeutics of viral infection.

RESULTS

The three major diagnostic methods available for SARS includes viral RNA detection by reverse transcription polymerase chain reaction (RT-PCR), virus induced antibodies by immunofluorescence assay (IFA) or by enzyme linked immunosorbant assay (ELISA) of nucleocapsid protein (NP). The spike glycoprotein of SARS-CoV is the major inducer of neutralizing antibodies. The receptor binding domain (RBD) in the S1 region of the spike glycoprotein contains multiple conformational epitopes that induces highly potent neutralizing antibodies. The genetically engineered attenuated form of the virus or viral vector vaccine encoding for the SARS-CoV spike glycoprotein has been shown to elicit protective immunity in vaccinated animals.

CONCLUSION

NP is the preferred target for routine detection of SARS-CoV infection by ELISA which is an economical method compared to other methods. The RBD of the spike glycoprotein is both a functional domain for cell receptor binding and also a major neutralizing determinant of SARS-CoV. The progress in evaluating a therapeutic or vaccine would depend on the avail ability of clinically relevant animal model.

Multicenter study of a new fully automated HBsAg screening assay with enhanced sensitivity for the detection of HBV mutants

In a multicenter study a new, fully automated Roche Diagnostics Elecsys HBsAg II screening assay with improved sensitivity to HBsAg mutant detection was compared to well-established HBsAg tests: AxSYM HBsAg V2 (Abbott), Architect HBsAg (Abbott), Advia Centaur HBsAg (Bayer) Enzygnost HBsAg 5.0 (Dade-Behring), and Vitros Eci HBsAg (Ortho). A total of 16 seroconversion panels, samples of 60 HBsAg native mutants, and 31 HBsAg recombinant mutants, dilution series of NIBSC and PEI standards, 156 HBV positive samples comprising genotypes A to G, 686 preselected HBsAg positive samples from different stages of infection, 3,593 samples from daily routine, and 6,360 unselected blood donations were tested to evaluate the analytical and clinical sensitivity, the detection of mutants, and the specificity of the new assay. Elecsys HBsAg II showed a statistically significant better sensitivity in seroconversion panels to the compared tests. Fifty-seven out of 60 native mutants and all recombinant mutants were found positive. Among 156 HBV samples with different genotypes and 696 preselected HBsAg positive samples Elecsys HBsAg II achieved a sensitivity of 100%. The lower detection limit for NIBSC standard was calculated to be 0.025 IU/ml and for the PEI standards ad and ay it was <0.001 and <0.005 U/ml, respectively. Within 2,724 daily routine specimens and 6.360 unselected blood donations Elecsys HBsAg II showed a specificity of 99.97 and 99.88%, respectively. In conclusion the new Elecsys HBsAg II shows a high sensitivity for the detection of all stages of HBV infection and HBsAg mutants paired together with a high specificity in blood donors, daily routine samples, and potentially interfering sera.

Hepatitis B virus genotype E surface antigen detection with different immunoassays and diagnostic impact of mutations in the preS/S gene

The major neutralizing epitope, the "a" determinant of the hepatitis B virus (HBV) genotype E surface antigen (HBsAg) is most divergent from that of genotype A, which is used for preparing monoclonal antibodies used in commercially available HBV reagents. To evaluate the performance of the latest generation of HBsAg detection assays with respect to genotype E HBsAg. Three commercial assays were evaluated using sera from 200 Nigerian patients compared to the preS/S sequence of DNA positive samples. Out of 200 samples, 61 and 103 gave concordant positive and negative results between the three HBsAg assays. Of 36 samples with discordant results, 35 were confirmed negative by neutralisation. One of the three assays showed significantly high rate of false positives (29 of 35). DNA positive samples with no detectable HBsAg or reduced HBsAg detection signals (<75% of mean signal obtained with HBsAg positive samples) revealed several mutations (V14A, F46S, N48T, L49R, I49T, D51G, A53V, P54L, Q82P, F83C, L127P, A184V, T189I, S204N, V224A), mostly outside the a-determinant. Several of these mutations are found as wild type nucleotides normally in genotype A and only exceptionally in genotype E. All three assays showed comparable sensitivities for genotype E HBsAg detection (98.4-100%) but differed considerably in specificity (84-99%). Failure to detect HBsAg antigen and differences in signal intensity were mainly associated with mutations in the preS/S gene outside the "a" determinant.

Diagnostic impact of the genetic variability of the hepatitis B virus surface antigen gene

The genetic variability of hepatitis B virus (HBV) represents a challenge for the sensitivity of immunologic and molecular based assays. Genotyping studies show that the genetic diversity of HBV is very high even in industrialized countries. The analytical sensitivity of HBsAg and anti-HBs assays may be dependent on HBV genotype or subtype and could possibly lead to false negative results in samples with low-level HBsAg. It is possible that the recognition of genotypes E and F may be impaired. Immunoassays based on polyclonal capture antibody show the highest sensitivity for the recognition of recombinant mutants or serum samples harboring mutant forms of HBsAg. However, they do not guarantee full sensitivity, especially for the detection of the G145R mutation and amino acid insertions or substitutions in positions 120-123. Detection of HBsAg needs to be improved by the introduction of new HBsAg assays able to recognize so far described S gene mutants and with a lower detection threshold than current immunoassays in order to detect smallest amounts of HBsAg in low level carriers. There is also a need for more complete epidemiological data on the prevalence of HBsAg mutants especially for G145R and assays for the (differential) screening of mutants need to be developed and evaluated.

Performance of a new-generation chemiluminescent assay for hepatitis B surface antigen

BACKGROUND

The usual criteria for analysis of hepatitis B surface antigen (HBsAg) are detection of HBsAg and result confirmation by antibody neutralization. We observed that with the Immulite 2000 HBsAg assay [Diagnostics Product Corporation (DPC)] a relatively high percentage of weakly reactive (WR) samples did not pass the neutralization step.

METHODS

For each of 3 lots of Immulite 2000 HBsAg reagent (DPC), we collected and analyzed HBsAg data from approximately 3000 to 4000 patient blood samples and compared these data with HBsAg data from 3393 samples tested with the Abbott Auszyme assay. For 127 samples with initially WR detection signals (relative signal/cutoff index of 1.00-2.5) on the Immulite 2000 HBsAg assay, we then measured hepatitis B (HB) viral load and/or other HB serologic markers.

RESULTS

The Immulite 2000 HBsAg assay produced more initially reactive results than the Abbott Auszyme method. Many of these reactive samples, however, were WR and did not meet the confirmation criteria in the neutralization test. Moreover, DNA PCR testing indicated that 22 of the 38 WR samples (58%) that did meet the confirmation criteria had no detectable HB viral DNA.

CONCLUSIONS

Immulite 2000 HBsAg assay results include a unique group of WR samples that are associated with both false-positive and false-negative results, regardless of neutralization status, and require careful interpretation. WR HBsAg samples should be reported as confirmed HBsAg reactive only if the samples not only meet the neutralization criteria but also are positive for other HB serologic markers such as anti-HB core total and anti-HB core IgM.

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

BACKGROUND

Automated immunoassay analyzers are used to identify hepatitis B virus (HBV) serum markers. In regions with high prevalence of HBV, it is imperative to compare test results from different immunoassay analyzers.

METHODS

Samples from 496 subjects were collected and HBV markers were determined (double-blind, parallel manner) using Abbott AxSYM, Roche Modular Analytics E170, and Abbott Architect i2000).

RESULTS

Concurrence between AxSYM and E170 was 97.78% for HBsAg, 91.13% for anti-HBs, 98.79% for anti-HBc, 98.39% for HBeAg, and 88.91% for anti-HBe. Positive rates of anti-HBs and anti-HBe from AxSYM were lower than E170 (P<0.01). Concurrence between AxSYM and Architect i2000 was 98.79% for HBsAg, 91.33% for anti-HBs, 95.97% for anti-HBc, 98.39% for HBeAg, and 95.77% for anti-HBe. Positive anti-HBs rates from AxSYM were lower than Architect i2000 (P<0.01). Concurrence between E170 and Architect i2000 was 97.38% for HBsAg, 94.15% for anti-HBs, 95.56% for anti-HBc, 99.60% for HBeAg, and 88.10% for anti-HBe. Positive anti-HBe rates using Architect i2000 were lower than E170 (P<0.01). Overall, the greatest differences were observed in samples with low-level serum HBV markers.

CONCLUSION

Significant discrepancies were observed among results for the 3 automated immunoassay analyzers, especially for low-level anti-HBs and anti-HBe results.

HBV virological assessment

Management of hepatitis B virus (HBV) infected patients involves serological diagnosis, quantitation of HBV-DNA and measurement of HBV drug resistance. Different serological markers such as HBsAg, anti-HBs, anti-HBc (total and IgM), HBeAg and anti-HBe are assessed by immunoassays in order to define the infection status. The emergence of surface mutants however is a continuous challenge to design more effective immunoassays. Commercially available quantitative HBV-DNA assays with increased sensitivity and wider linear range give a more accurate estimate of viral replication and contribute decisively in the initiation and the monitoring of the response to HBV therapy. Genotypic drug resistance assays are important diagnostic tools, since the administration of nucleoside/nucleotide analogues to HBV infected patients leads to the development of drug resistance patterns very much dependent on the treatment regimen. Special issues have to be taken into consideration regarding HBV/HIV-1 co-infected patients, since concominant HIV and HBV replication results in higher rates of HBV replication. Current efforts are focused on the standardization of HBV-DNA assays (qualitative and quantitative), of HBV drug resistance assays as well as in the development of new assays and markers that will help in the prognosis and management of HBV infection (quantitative detection of pre-core mutants and HBV ccc-DNA assays).

Evaluation of a new automated assay for hepatitis B surface antigen (HBsAg) detection VIDAS HBsAg Ultra

In a multicenter study a new automated screening assay, VIDAS HBsAg Ultra (long (L) and short (S) incubation protocol (Biomérieux, Marcy l'Etoile, France), was compared to a well established test (AxSYM HBsAg v2, Abbott Diagnostics, Wiesbaden, Germany) for the detection of hepatitis B virus (HBV) surface antigen (HBsAg). A total of 32 seroconversion panels, sera from the chronic phase of infection, dilution series of the WHO standard, S gene mutants (recombinant mutants and diluted and undiluted sera harbouring mutants with single or multiple amino acid (aa) substitutions, n = 40) and isolated anti-HBc positive samples were tested for the evaluation of sensitivity. Sera from HBsAg negative blood donors, pregnant women, hospitalized patients and potentially cross-reactive samples were investigated to determine the specificity of the new assay. The VIDAS HBsAg Ultra (L+S) had a higher sensitivity than the alternative assay for the detection of acute hepatitis B in seroconversion panels. The mean time of the diagnostic window was shortened with the VIDAS HBsAg Ultra (L) and (S) in comparison with the AxSYM HBsAg v2 by 1.06 and 0.66 days, respectively. The VIDAS HBsAg Ultra (L) did not detect one diluted sample out of six bearing the single aa G145R substitution, and two out of 12 diluted samples harbouring multiple aa substitutions. The analytical sensitivity of the assays varied from one surface mutant to another. While no false positive results were obtained with the VIDAS HBsAg Ultra (L+S) among potentially interfering samples, four false positives were detected with the AxSYM HBsAg v2. The respective values for sensitivity for the VIDAS HBsAg Ultra (L), (S) and the AxSYM HBsAg v2 were 99.07%, 97.87% and 94.14%. The specificities were 100% (VIDAS HBsAg Ultra L and S) and 99.6% (AxSYM HBsAg v2). In conclusion, the VIDAS HBsAg Ultra is highly sensitive and specific and represents an improvement for the detection of HBsAg in routine diagnostic laboratories.

A new HBsAg screening assay designed for sensitive detection of HBsAg subtypes and variants

The design of a new HBsAg screening assay, the Hepanostika HBsAg Ultra is based on the use of monoclonal antibodies raised against native wild-type HBsAg and reactive with HBsAg in which the common 'a'-determinant is modified by site-directed mutagenesis of four of the cysteine moieties. The design was checked using the same cysteine variants and samples from patients known to be infected with HBsAg variants. The results found were compared with other state-of-the-art commercial screening assays. The design of the Hepanostika HBsAg Ultra enabled detection of all variant HBsAg-positive samples in contrast to the other commercial assays. An additional 980 samples were tested to assess the specificity and sensitivity of the Hepanostika HBsAg Ultra. Screening of presumed negative serum and plasma samples resulted in a specificity of 100%. This makes the Hepanostika HBsAg Ultra the first screening assay with a design able to detect HBsAg variants with high sensitivity and specificity.

Safety of blood supply in the Caribbean countries: Role of screening blood donors for markers of hepatitis B and C viruses

BACKGROUND

Blood transfusions carry risks of untoward reactions, including the transmission of infections, such as hepatitis B and C. Proper blood donor recruitment and selection, and adequate laboratory screening for infectious markers diminish the risk of transfusion-transmitted infections.

OBJECTIVES

To estimate the potential risk of acquiring transfusion-transmitted infections by hepatitis B or hepatitis C in 24 Caribbean countries during the period of 1996 to 2003.

STUDY DESIGN

Official national reports for 1996, 2000-2003 of the yearly number of blood donors, screening coverage, and prevalence of serological markers for infectious diseases were used to estimate the risk of patients receiving an HBV- or HCV-positive unit of blood, and of developing an infection after receiving a positive unit. Estimates of number of infections transmitted through transfusion and number of infections prevented by screening of blood were also obtained.

RESULTS

During the period analyzed, HBV screening coverage among blood donors was 100% in all countries with the exception of Grenada (0% in 1996) and Saint Lucia (99.5% in 2002). For HCV, only 10 countries reported universal screening in 1996, while 15 did in 2003. The number of countries that did not screen any units for HCV decreased from 11 in 1996 to five in 2003. In general, high prevalence rates of HBV (10-75 per 1000 donors) and HCV (7-19.3 per 1000 donors) markers were found in the majority of countries. We estimated that 235 infections by HCV (1:12471 donations) and two infections by HBV (1:1465373) were transmitted through transfusion because of lack of screening. On the other hand, screening of blood for transfusion prevented 21 005 HCV and 22 100 HBV infections.

CONCLUSIONS

Blood donor recruitment and coverage of screening for transfusion-transmitted infections, especially HCV, must be improved in the Caribbean countries.

Rapid and sensitive HBsAg immunoassay based on fluorescent nanoparticle labels and time-resolved detection

The detection of hepatitis B virus in blood specimens is carried out commonly by measuring surface antigen (HBsAg) levels with assays designed for various random access immunoanalysers or rapid near-patient testing. These methods leave much to be desired in performance or throughput. The aim of this study was to develop a nanoparticle label-based rapid and sensitive HBsAg immunoassay and evaluate its performance compared to a well-established reference immunoassay (Enzygnost HBsAg 5.0). The assay developed is based on kinetic format and relies on one-step two-site antibody-antigen interaction. Europium(III)-chelate-doped nanoparticles and microtiter wells were coated with anti-HBsAg monoclonal antibodies specific for discrete epitopes. The adaptation of nanoparticle labels for quantitative HBsAg detection showed improved sensitivity (LLD: 0.028 ng/ml) and dynamics (up to 1000 ng/ml) with reasonably low coefficients of variation (concentration-CV%s 2.8-21.9%). Furthermore, concurrent sample runs with the ELISA reference method showed 100% agreement. The time required for the assay was only 10 min facilitating a rapid and convenient method for hepatitis B screening.

Allergen-specific IgE measured by a continuous random-access immunoanalyzer: interassay comparison and agreement with skin testing

BACKGROUND

Our aims were to evaluate the performance of a fully automated system for measuring circulating allergen-specific IgE (sIgE) against an established in vitro assay and to assess the system's diagnostic accuracy against objective clinical criteria for identifying sensitization to specific allergens.

METHODS

Using both the IMMULITE 2000 Allergy system (IML) and an assay based on the widely used ImmunoCAP technology (CAP), we measured sIgE in serum samples from 169 persons with suspected allergies to airborne or insect venom allergens. Skin testing outcome served as the clinical comparison method.

RESULTS

Interassay classification agreement between the IML and CAP, relative to the usual allergen-specific IgE cutoff of 0.35 kIU/L, ranged from 76% (yellow jacket venom) to 95% (orchard grass); agreement was 88.3% for all 9 allergens combined (766 results). The 90 discordant results, when resolved by skin testing, showed better agreement with the IML (72%) than with the CAP (28%). Compared with skin testing, for each of the 9 allergens studied, the area under the ROC curve was at least as large for the IML as for the CAP, reflecting in part the more extensive working range of the IML (0.10-100 kIU/L vs 0.35-100 kIU/L for CAP).

CONCLUSION

Laboratory testing for sIgE can be performed on a fully automated, random-access system with an extended working range and with diagnostic accuracy for representative allergens equivalent to or better than that of the semiautomated CAP technology.

Evaluation of two chemiluminescent immunoassays of ADVIA centaur for hepatitis B serology markers

BACKGROUND

This study evaluated the performance of 2 Bayer Hepatitis B Chemiluminescent Assays by comparing their performance to the corresponding DPC Immulite 2000 assays.

METHODS

953 samples were tested by both Immulite 2000 and Centaur HBsAg methods; and 75 samples were tested by both Immulite 2000 and Centaur anti-HBc IgM methods.

RESULTS

The overall agreement between Immulite 2000 and ADVIA Centaur anti-HBc IgM assays was 100%. The agreement between Immulite 2000 and Centaur HBsAg assays was 100% for Immulite 2000 positive samples. The overall agreement for HBsAg negative samples was 99.9% after confirmation result was included. However, discrepancy between the 2 assays was observed in 53 samples which were tested initially as "weakly reactive"(index 1.0-1.95) but were not confirmed subsequently by the neutralization test on Immulite 2000. All 53 samples tested negative by Centaur HBsAg assay at the initial run. Furthermore, one Immulite 2000 HBsAg negative sample was reactive and confirmed by Centaur assay.

CONCLUSIONS

While the performance of Bayer Hepatitis B HBsAg and aHBc IgM assays are in good agreement with corresponding DPC assays, the Bayer HBsAg assay is more efficient than the Immulite 2000 assay with its better separation of signal and background noise, and its complete automation features.

Recent developments in the diagnosis and monitoring of HBV infection and role of the genetic variability of the S gene

Recent developments in the laboratory diagnosis of hepatitis B virus infection include the optimization of key serologic markers, including hepatitis B virus surface antigen and antihepatitis B virus core antibody, as well as the development of automated nucleic acid amplification assays. There is still a lack of standardization for nucleic acid amplification assays that are used for the monitoring of antiviral therapy and follow-up of chronic infection and the clinical significance of hepatitis B virus DNA levels need to be clarified. Although highly sensitive automated nucleic acid amplification assays for blood donor screening are available, their implementation is still subject to discussion and certain countries rejected hepatitis B virus DNA testing for blood donation due to poor cost effectiveness. Genetic variability of hepatitis B virus constitutes a major challenge for diagnosis of hepatitis B virus infection, particularly with regard to hepatitis B virus surface antigen detection, antihepatitis B virus surface antigen quantification and nucleic acid amplification assays. The performances of hepatitis B virus surface antigen enzyme immunoassays in regard to genotype and surface antigen variability need to be further improved. Polyclonal antibody-based hepatitis B virus surface antigen enzyme immunoassays, although they cannot guarantee 100% sensitivity, demonstrate superior S gene mutant recognition to assays using monoclonal capture and tracer antibodies. Isolated antihepatitis B virus core reactivity is an unusual but frequent result, which requires a test algorithm for resolution and hepatitis B virus DNA detection with sensitive nucleic acid amplification assays in order to exclude occult hepatitis B virus infection.

Genetic variability of the S gene of hepatitis B virus: clinical and diagnostic impact

The genetic variability of hepatitis B virus (HBV) represents a challenge for the sensitivity of immunologic and molecular based assays. Based on sequence divergence in the entire genome of >8%, HBV genomes have been classified into eight groups designated A to H. The genotypes of HBV have distinct geographical distributions. Although preliminary clinical studies seem to indicate that there is an association between HBV genotype and natural history of infection and response to antiviral therapy, further evaluations on larger collectives of patients are necessary to give a clearer picture of the subject. The analytical sensitivity of HBsAg and anti-HBs assays may be dependent on HBV genotype or subtype. The influence of genotypic variability on the sensitivity of nucleic acid amplification tests (NAT) has so far been poorly investigated. Preliminary results show that new real-time NAT detect genotypes A to G with an equal sensitivity. Different mechanisms intervening at the translational or post-translational level, including conformational changes, hydrophobic changes, insertion of basic residues and reduced synthesis or secretion of HBsAg may account solely or in conjunction for escape mutations to the immune response and to detection in HBsAg immunassays. The clinical significance of S-gene mutants, needs in analogy to that of HBV genotypes, to be further investigated. HBV mutants are stable over time and can be transmitted horizontally or vertically. The sensitivity of HBsAg assays for mutant detection is continuously improved. Immunoassays based on polyclonal capture antibody show the highest sensitivity for the recognition of recombinant mutants or serum samples harboring mutant forms of HBsAg. However, they do not guarantee full sensitivity. Detection of HBsAg needs to be improved by the introduction of new HBsAg assays able to recognize so far described S-gene mutants and with a lower detection threshold than current immunoassays in order to detect smallest amounts of HBsAg in low level carriers. There is also a need for more complete epidemiological data on the prevalence of HBsAg mutants and strategies for the (differential) screening of mutants need to be developed and evaluated.

Detection of an acute asymptomatic HBsAg negative hepatitis B virus infection in a blood donor by HBV DNA testing

The issue of HBV DNA screening on blood donations is controversially discussed since the economic impact of post-transfusion hepatitis B is expected to be relatively low. We report on a case of HBsAg negative unapparent acute HBV infection, which was detected by HBV NAT testing on 96-member maxi-pools with a commercially available NAT assay, which has a detection threshold of 3 IU/mL of plasma. The presence of an HBsAg escape mutant could be excluded by sequencing the amplified DNA. Follow-up testing showed the presence of an acute HBV infection (anti-HBc-IgM positive) and finally anti-HBs seroconversion. Although the reduction of the diagnostic window with NAT screening on maxi-pools may be relatively low, it may help to improve the residual risk of blood donation, especially in asymptomatic HBV infection, where the HBsAg positive period may be very short and low levels of circulating surface antigen are present. It would also permit to detect occult HBV infection in chronic carriers who are HBsAg negative. Since the viral load in chronic isolated anti-HBc positive carriers is low, there is a potential risk for failure of HBV DNA detection with pool-PCR in blood donors. Anti-HBc screening would reduce the residual risk.

Sensitive and specific monoclonal antibody-based capture enzyme immunoassay for detection of nucleocapsid antigen in sera from patients with severe acute respiratory syndrome

A rapid antigen test for the diagnosis of severe acute respiratory syndrome (SARS) is essential for control of this disease at the point of management. The nucleocapsid (N) protein of SARS-associated coronavirus (SARS-CoV) is abundantly expressed in infected-cell culture filtrate as demonstrable by Western blotting using convalescent-phase sera from patients with SARS. We used monoclonal antibodies specifically directed against N protein to establish a sensitive antigen capture sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of SARS-CoV. The assay employed a mixture of three monoclonal antibodies for capture and rabbit polyclonal antibodies for detection of serum antigen in 32 cases of clinically probable SARS as defined by the World Health Organization during the epidemic in Guangzhou, China. Recombinant N protein was used as a standard to establish a detection sensitivity of approximated 50 pg/ml. The linear range of detection in clinical specimens was from 100 pg/ml to 3.2 ng/ml. Using a panel of sera collected at different points in time, the amount of circulating N antigen was found to peak 6 to 10 days after the onset of symptoms. The sensitivity of the assay was 84.6% in 13 serologically confirmed SARS patients with blood taken during the first 10 days after the onset of symptoms (11 of 13). The specificity of the assay was 98.5% in 1,272 healthy individuals (1,253 of 1,272). There was no cross-reaction with other human and animal coronaviruses in this assay. In conclusion, a sensitive and quantitative antigen capture ELISA was established for the early diagnosis and disease monitoring of SARS-CoV infection.