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

Efficient implementation of hepatitis B surface antigen confirmatory neutralization tests

INTRODUCTION

To prevent misreporting of false positives in the hepatitis B surface antigen (HBsAg) assay, it is recommended to confirm the low-positive cases with neutralization tests. However, currently not many facilities are implementing this due to the additional cost. The aim of this study was to clarify the risk factors for false positives in the high-sensitivity HBsAg quantitative tests to reduce the neutralization tests.

METHODS

In this retrospective cohort study, we analyzed 47,305 patients who had their HBsAg value measured at Sapporo Medical University Hospital between November 2016 and March 2022. The patients eligible for the neutralization tests were those with HBsAg values between 0.005 and 1.000, even after reexamination by high-speed centrifugation.

RESULTS

HBsAg quantitative tests were performed in 71,475 tests. Of these, 817 tests and 376 patients were subjected to neutralization tests. Of the patients who met the criteria, 329 were included in this study. Fifty-seven cases (17%) had negative results in the neutralization tests, suggesting false positives for the HBsAg assay. Multivariate analysis showed that younger age (adjusted odds ratio [aOR] 6.57), female sex (aOR 2.32), lower HBsAg values (aOR 59.6), and reagent improvement (aOR 2.06) were independent risk factors for false positives. The false-positive rate was actually high at 33.1% in the HBsAg range of 0.005-0.049 IU/mL and at 1.2% in the range above 0.050 IU/mL.

CONCLUSIONS

Confirmatory neutralization tests should be performed at least in the range of 0.005-0.049 IU/mL where quantification is possible with a higher-sensitivity assay.

ARCHITECT HBsAg Next assay is positioned better to resolve and refine challenging weak reactive clinical samples

BACKGROUND

Ultrasensitive HBsAg assays are replacing the previous versions. Unlike the sensitivity, the specificity, and its positioning to resolve weak-reactives (WR) are not studied. We investigated the ability of ARCHITECT HBsAg-Next (HBsAg-Nx) assay to resolve WR and sought its clinical validation and correlation with confirmatory/reflex testing.

METHODS

Among 99,761 samples between Jan 2022 - 2023, 248 reactive samples in HBsAg-Qual-II were compared with HBsAg-Nx assay. Sufficient samples were further subjected to neutralization (n = 108) and reflex (anti-HBc total/anti-HBs antibody) testing.

RESULTS

Out of 248 initial reactive samples in HBsAg-Qual-II, 180 (72.58%) were repeat reactive, and 68 (27.42%) were negative, whereas in HBsAg-Nx, 89 (35.89%) were reactive and 159 (64.11%) were negative (p<0.0001). Comparing the results of two assays (Qual-II/Next), 57.67% (n = 143) were concordant (++/-) and 105 (42.33%) were discordant (p = 0.0025). Testing of HBsAg-Qual-II + & HBsAg-Nx - samples revealed that 85.71% (n = 90) were anti-HBc total negative and 98.08% (n = 51) were not neutralized as well as significant proportion (89%) had no clinical correlation. The proportion of samples neutralized was significantly different between ≤5 S/Co (26.59%) and >5 S/Co (71.42%) (p = 0.0002). All samples (n = 26) with enhanced reactivity in HBsAg-Nx were effectively neutralized, while samples with no increase in reactivity, 89% (n = 72) failed neutralization (p=<0.001).

CONCLUSIONS

HBsAg-Nx assay is positioned better to resolve and refine challenging WR samples than Qual-II which correlated well with confirmatory/reflex tests and clinical disease. This superior internal benchmarking significantly reduced the cost and quantum of retesting, confirmatory/reflex testing in the diagnosis of HBV infection.

An Approach for Evaluating Potential Screening Thresholds Using Biomarker Population Distribution and Analytical Imprecision

BACKGROUND

A common approach in laboratory medicine is to use a simple but sensitive test to screen samples to identify those that require additional investigation with a more complex and informative method. Selection of screening thresholds can be guided by biomarker distribution in the tested population and the analytical imprecision of the method.

METHODS

A simulation using joint probabilities derived from the population distribution for galactose-1-phosphate uridylyltransferase (GALT) activity and the analytical imprecision for the GALT assay was used to estimate the number of samples that would require repeat analysis and the number of samples with possibly false-negative screening determinations due to analytical imprecision.

RESULTS

In the case of GALT activity, screening a conservative initial threshold 6 standard deviations from the confirmation threshold can essentially eliminate the chance of a false-negative screening determination due to analytical imprecision. The trade-off is a greater number of samples requiring follow-up testing (n = 222, equivalent to 0.15% of samples annually).

CONCLUSIONS

Selection of thresholds in a screening algorithm is informed by estimates of the number of samples that would require repeat testing and the number that could be false negative due to analytical imprecision.

Utility of grey zone testing strategy in transfusion transmissible infection testing in blood bank is of limited value!

Several blood banks use grey zone (GZ) phenomenon (defined as samples with optical density within 10% below the cut off in enzyme immuno-assay [EIA]/chemiluminescence immunoassay [CLIA]) to further augment blood safety. There is paucity of data regarding usefulness of GZ sample and its application in Transfusion Transmissible Infection (TTI) screening procedures in blood transfusion services. We looked at our GZ sample results and their confirmatory test results to verify if it adds to blood safety in our set-up? We performed a prospective analytical study on blood donors' samples over two years. All the donors' samples were screened for TTI using CLIA. Samples with signal/cut-off ratio between ≥0.90 and <1.00 were classified under GZ. They were re-tested in duplicate and submitted to confirmatory testing: Neutralization Test for HBsAg, Immunoblot for HCV, and Western blot for HIV. Among the 50,064 blood donors donating the blood during study period, 573 (1.14%) donors were reactive for HBsAg, HCV, and HIV. Forty-seven (0.1%) TTI samples were GZ, but none was "confirmed positive." The utility of GZ testing seems to be limited. However, this may be continued for sake of "erring on the side of caution" and since this only results in negligible wastage (0.1%) of blood units.

Deceased tissue donor serology and molecular testing for HIV, hepatitis B and hepatitis C viruses: a lack of cadaveric validated tests

Vital to patient safety is the accurate assessment and minimization of risk for human immunodeficiency virus (HIV), Hepatitis C (HCV), and Hepatitis B (HBV) virus transmission by deceased donor organ and tissue transplantation. The pathogens are tested by serological kits based on enzyme-linked immunosorbent assay (ELISA), chemiluminescence (CLIA) and eletrochemiluminescence (ECLIA) immunoassays. Organ transplantation is a highly successful life-saving treatment in Brazil, but the Brazilian Health Surveillance Agency currently mandates that all deceased organ donors are screened for HIV, HCV and HBV following living donor policies. In this review, six ELISA (Wama^®, Bio-Rad^®, Biomerieux^®, DiaSorin^®, Acon Biotech^® and Biokit^®), three CLIA (Abbott^®, Siemens^®, Diasorin^®) and one ECLIA (Roche^®) were utilized for evaluating the effectiveness of those serological tests for deceased donors in Brazil according to manufacturer's guidelines. NAT for HIV, HCV and HBV can assist with detection of pre-seroconversion for those infections, and only Cobas^® TaqScreen MPX^® test, the Tigris System^® Procleix Ultrio Assay^® and the Bio-Manguinhos^® HIV/HCV/HBV NAT are commercially available. Between all the tests, only the manufacturer Abbott^® and Cobas^® TaqScreen MPX^® test are currently validated for cadaver samples.

Clinical and epidemiological profile of female blood donors with positive serology for viral hepatitis B

INTRODUCTION

Since women are frequently the minority among blood donors worldwide, studies evaluating this population usually reflect male features. We assessed the features of female blood donors with positive serology for HBV and compared them with those of men.METHODS The study comprised consecutive blood donors referred to a specialized liver disease center to be evaluated due to HBsAg- and/or anti-HBc-positive tests.

RESULTS

The study encompassed 1,273 individuals, 219 (17.2%) of whom were referred due to positive HBsAg test and 1,054 (82.8%) due to reactive anti-HBc test. Subjects' mean age was 36.8±10.9 years, and 28.7% were women. Female blood donors referred for positive HBsAg screening tests demonstrated higher prevalence of healthcare workers (9.3% vs 2.5%) and lower prevalence of sexual risk behaviors (15.1% vs 41.1%) and alcohol abuse (1.9% vs 19.8%) compared to men. Women had lower ALT (0.6 vs 0.8×ULN), AST (0.6 vs 0.8×ULN), direct bilirubin (0.2 vs 0.3mg/dL), and alkaline phosphatase (0.5 vs 0.6×ULN) levels and higher platelet count (223,380±50,293 vs 195,020±53,060/mm3). Women also had a higher prevalence of false-positive results (29.6% vs 17.0%). No differences were observed with respect to liver biopsies. Female blood donors referenced for reactive anti-HBc screening tests presented similar clinical, epidemiological, and biochemical characteristics to those reported for positive HBsAg screening tests and similarly had a higher prevalence of false-reactive results.

CONCLUSIONS

Compared to men, female blood donors with positive HBsAg and/or anti-HBc screening tests demonstrated higher prevalence of professional risk and false-positive results and reduced alteration of liver chemistry.

Impact of grey zone sample testing by enzyme-linked immunosorbent assay in enhancing blood safety: Experience at a tertiary care hospital in North India

BACKGROUND

Enzyme-linked immunosorbent assay (ELISA) used for screening blood donors for transfusion transmitted infections (TTIs) can sometimes fail to detect blood donors who are recently infected or possessing the low strength of pathogen. Estimation of a grey zone in ELISA testing and repeat testing of grey zone samples can further help in reducing the risks of TTI in countries where nucleic acid amplification testing for TTIs is not feasible.

MATERIALS AND METHODS

Grey zone samples with optical density (OD) lying between cut-off OD and 10% below the cut-off OD (cut-off OD × 0.9) were identified during routine ELISA testing. On performing repeat ELISA testing on grey zone samples in duplicate, the samples showing both OD value below grey zone were marked nonreactive, and samples showing one or both OD value in the grey zone were marked indeterminate. The samples on repeat testing showing one or both OD above cut-off value were marked positive.

RESULTS

About 119 samples (77 for hepatitis B virus [HBV], 23 for human immunodeficiency virus [HIV], and 19 for hepatitis C virus [HCV]) were found to be in grey zone. On repeat testing of these samples in duplicate, 70 (58.8%) samples (45 for HBV, 12 for HIV, and 13 for HCV) were found to be reactive. Six (5%) samples (four for HBV, one for HIV, and one for HCV) were found to be indeterminate.

CONCLUSION

Seventy donors initially screened negative, were found out to be potentially infectious on repeat grey zone testing. Thus, estimation of grey zone samples with repeat testing can further enhance the safety of blood transfusion.

Diagnostic validity of the chemiluminescent method compared to polymerase chain reaction for hepatitis B virus detection in the routine clinical diagnostic laboratory

Background:

Hepatitis B virus (HBV) is the most common significant chronic viral infection world-wide. Hepatitis B surface antigen (HBsAg) has been the principal target for laboratory testing to identify active infection by HBV. We aimed to find out diagnostic validity of the Liaison chemiluminescent method compared to the polymerase chain reaction (PCR) method for HBV detection in the routine clinical diagnostic laboratory.

Materials and Methods:

From 350 patients suspicious of having infection with HBV, serum samples were separated and used for testing HBsAg by two methods of Liaison chemiluminescent immunoassay, with HBsAg confirmatory test and PCR method.

Results:

According to the PCR results as assumed as gold standard method with 100% sensitivity and specificity, detection rate sensitivity of chemiluminescent with confirmatory test was 96% and its specificity was 100%, and for chemiluminescent without confirmatory test sensitivity and specificity were 100% and 70%, respectively. Also for chemiluminescent with confirmatory test, positive predictive value (PPV) was 100% and its negative predictive value (NPV) was 97%, compared to chemiluminescent without confirmatory test with PPV and NPV equal to 71% and 100%, respectively.

Conclusions:

It is possible to conclude that in the majority of the HBV cases, the diagnostic value of chemiluminescent method compared to the PCR method is acceptable, except in low indexes positive cases that need further investigation with the PCR method.

Hepatitis B surface antigen confirmatory testing for diagnosis of hepatitis B virus infection in Taiwan

This study aimed to examine the application of hepatitis B surface antigen (HBsAg) confirmatory testing when diagnosing hepatitis B infection among young persons in Taiwan with a low prevalence rate of hepatitis B infection. HBsAg status, the presence of antibodies against HBsAg (anti-HBs), and the presence of antibodies against hepatitis B core antigen (anti-HBc) were compared among 403 graduate students (mean age 22.8 ± 0.7 years) and 1,745 undergraduate students (18.6 ± 1.0 years) from one university, and 367 adult subjects (41.1 ± 15.8 years) in 2008. Any HBsAg-positive subjects were tested with an HBsAg confirmatory test. Chi-square tests for trend and predictive values of positivity (PVP) when using HBsAg-positive only for determining confirmed cases of hepatitis B infection were compared across the three cohorts. The prevalence of HBsAg positivity among subjects decreased from 16.3% in the adults to 5.2% in the graduate students and then to 2.8% for the undergraduate students (P = 0.0007). The PVP of HBsAg testing when determining cases of hepatitis B decreased from 0.97 for the adults to 0.81 for the graduate students and then to 0.56 for the undergraduate students (P < 0.0001). Thus, a significant decrease in the true-positive rate of HBsAg among the students born after the introduction of hepatitis B vaccination was observed only when HBsAg testing was applied. Additional neutralization tests may therefore become mandatory for persons with a positive HBsAg test result who were born after the commencement of the universal neonatal hepatitis B vaccination program in Taiwan.

Pitfall of hepatitis B surface antigen testing in a kidney transplant recipient presenting hepatitis B reactivation

Diagnosis of hepatitis B virus (HBV) infection based on hepatitis B surface antigen (HBsAg) detection can be hampered in the setting of HBV reactivation in immunocompromized patients with prior serology indicating past cured infection, and can be associated with severe or fulminant and fatal hepatitis. We present a case of HBV reactivation in a renal transplant patient in whom HBsAg failed to be confirmed as a true positive result. One year after transplantation, systematic testing showed HBsAg positivity with a titer at 244 pg/mL, anti-hepatitis B core antibody and concurrent anti-hepatitis B surface antibody positivity. Confirmation of HBsAg detection by seroneutralization did not confirm HBsAg positivity, indicating that HBsAg detection was a false positive result. Notwithstanding, HBV DNA titer in serum was concurrently 8.6 Log IU/mL. HBV DNA sequencing showed a genotype D and several amino acid substitutions within HBsAg, including some previously involved in impaired diagnosis and altered immunogenicity. Although no perturbation of liver biochemical markers was observed, treatment with tenofovir was introduced. One month later, HBV DNA level had decreased by 2.6 Log IU/mL and no clinical and biochemical symptoms of hepatitis had occurred. The present case underlines that serologic diagnosis of HBV reactivation can be tricky in transplant recipients with a prior serology indicating past HBV infection. This prompts to perform HBV DNA testing in case of positive HBsAg testing, regardless of the result of neutralization by anti-HBs antibodies.

HBV, HCV and HIV seroprevalence among blood donors in Istanbul, Turkey: how effective are the changes in the national blood transfusion policies?

The national blood transfusion policies have been changed significantly in recent years in Turkey. The purpose of this study was to determine the prevalence of HBV, HCV, and HIV in blood donors at the Red Crescent Center in Istanbul and to evaluate the effect of changes in the national blood transfusion policies on the prevalence of these infections. The screening results of 72695 blood donations at the Red Crescent Center in Istanbul between January and December 2007 were evaluated retrospectively. HBsAg, anti-HCV, and anti-HIV-1/2 were screened by microparticle enzyme immunoassay (MEIA) method. Samples found to be positive for anti-HIV 1/2 and anti-HCV were confirmed by Inno-Lia HCV Ab III and Inno-Lia HIV I/II Score, respectively. The seropositivity rates for HBsAg, anti-HCV, and anti-HIV-1/2 were determined as 1.76%, 0.07%, and 0.008%, respectively. Compared to the previously published data from Red Crescent Centers in Turkey, it was found that HBV and HCV seroprevalances decreased and HIV seroprevalance increased in recent years. In conclusion, we believe that the drop in HBV and HCV prevalence rates are likely multifactorial and may have resulted from more diligent donor questioning upon screening, a higher level of public awareness on viral hepatitis as well as the expansion of HBV vaccination coverage in Turkey. Another factor to contribute to the decreased prevalence of HCV stems from the use of more sensitive confirmation testing on all reactive results, thereby eliminating a fair amount of false positive cases. Despite similar transmission routes, the increase in HIV prevalence in contrast to HBV and HCV may be linked to the increase in AIDS cases in Turkey in recent years.

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.

Do we need an 'in-house' neutralization assay for confirmation of hepatitis B surface antigen? Answers from a tertiary care hospital in India

BACKGROUND AND AIMS

Hepatitis B surface antigen (HBsAg) is an important serological marker for diagnosis of hepatitis B virus (HBV) infection. Commercial kits for detection of HBsAg emphasize confirmation by neutralization assays. In this study, we have standardized an 'in-house' neutralization test for HBsAg confirmation.

METHODS

Among 6684 HBsAg-positive samples, 615 were subjected to an 'in-house' HBsAg neutralization test (NT). Of these, 91 (100%) high-reactive samples (optical density [OD] 1.000-3.000) and 286 (93%) of 289 low-reactive samples (OD < 1.000) were neutralized, and 235 (100%) grey-zone reactive samples were 'in-house' NT negative. Eighty-four samples of varying reactivities that were tested by the 'in-house' NT were compared with a commercial NT (AxSYM, Abbott).

RESULTS

The 'in-house' NT showed an excellent agreement (kappa = 0.83, P < 0.001) with the commercial confirmatory assay. The sensitivity, specificity, positive and negative predictive values were 90%, 94%, 96% and 87%, respectively.

CONCLUSION

The enzyme immunoassay-based 'in-house' HBsAg neutralization assay is a feasible alternative to the commercial HBsAg confirmatory assay. This technique is easily adaptable, cost-effective and reliable for the confirmation of HBsAg in a low resource setting, enhancing the overall quality of HBsAg screening.