Frequency of hepatitis B surface antigen variants (HBsAg) in hepatitis B virus genotype B and C infected East- and Southeast Asian patients: Detection by the Elecsys® HBsAg II assay

Frequency of HBsAg variants in occult hepatitis B virus infected patients and detection by ARCHITECT HBsAg quantitative

Objective

To analyze the amino acid substitution caused by mutations in the major hydrophilic region (MHR) of the S-region genes in the serum samples of occult hepatitis B virus infection (OBI), and to explore the reasons for the missed detection of HBsAg.

Method

The full-length gene of the S-region in hepatitis B virus(HBV) in the chronic hepatitis B virus(CHB)(10 samples) and OBI groups(42 samples) was amplified using a lab-developed, two-round PCR amplification technology. The PCR amplification products were sequenced/clone sequenced, and the nucleotide sequences of the S-region gene in HBV were compared to the respective genotype consensus sequence.

Results

Only 20 of the 42 samples in the OBI group had the S-region genes successfully amplified, with the lowest HBV DNA load of 20.1IU/ml. As S-region genes in HBV, 68 cloned strains were sequenced. In the OBI and CHB groups MHR region, with a mutation rate of 3.21% (155/4828) and 0.70% (5/710). The genetic mutation rate was significantly higher in the OBI group than in the CHB group (P<0.05). The common mutation types in the MHR region were: I126T, L162R, K122E, C124R, and C147Y.Mutations at s122, s126, and s162 were associated with subgenotypes, most of which being C genotypes. The high-frequency mutation sites L162R and K122E found in this study have not been reported in previous literature.

Conclusion

The results of this study confirmed that MHR mutations can cause the missed detection of HBsAg, giving rise to OBI.

Clinical trial and performance evaluation of the Wantai HBsAg (CMIA) diagnostic kit for screening blood donors in China

In China, according to the 'Technical Operating Procedures for Blood Stations (2019 Edition),' blood stations are authorized to utilize Chemiluminescence Immunoassay (CLIA) to detect pathogen markers linked with transfusion-transmissible infections. However, currently, there is no approved CLIA reagent for the screening of blood-borne diseases in China, specifically for the detection of Hepatitis B surface antigen. The objective of this research project is to conduct a comprehensive evaluation of the performance of the Wantai Chemiluminescent Microparticle Hepatitis B surface antigen reagent. This study evaluates the performance of the Wantai Chemiluminescent Microparticle Immunoassay (CMIA) on the Wan200 + analyzer in screening for Hepatitis B Surface Antigen (HBsAg) in blood samples. The clinical trial component of this evaluation is included as part of the documentation submitted to the National Medical Products Administration (NMPA) of China for the approval of blood screening reagents. The evaluation plan of this study encompasses two main components: clinical trials and performance assessment. We adopted a controlled trial design, utilizing the WanTai Chemiluminescent Microparticle Immunoassay (CMIA) on the Wan200 + analyzer and the Enzyme-Linked Immunosorbent Assay (ELISA) to screen for Hepatitis B Surface Antigen (HBsAg) in routine blood donor samples and reference serum panel samples. To ensure the accuracy of the screening, we additionally employed Abbott's ELISA reagents and HBV DNA for validation. The assessment primarily focused on key performance indicators such as sensitivity, specificity, and analytical sensitivity. Moreover, this clinical trial data has been included as part of the submission to China's National Medical Products Administration (NMPA). In the clinical trials of this study, a total of 10,470 blood donor samples underwent simultaneous testing using both CMIA and ELISA methods. Across two clinical trials, there was remarkable concordance between CMIA and the two ELISA reagents, with Kappa values exceeding 0.82. Among the 269 samples that were double-reactive in the enzyme immunoassay (ELISA) tests, CMIA exhibited a 100% reactivity detection rate. However, CMIA produced 14 and 6 false-positive results in the respective clinical trials, resulting in specificities of 99.73% and 99.89%. In contrast, the specificities for Wantai ELISA and Xin Chuang ELISA were both greater than 99.94%.When testing samples in the gray zone serum plates, CMIA's detection limit significantly exceeded that of the two ELISA assays. CMIA had a detection cutoff of 0.05 IU/mL, while the two ELISA reagents had cutoffs of 0.1 IU/mL and 0.09 IU/mL, respectively. CMIA's detection limits for the adr and adw subtypes were 0.05 IU/mL, and for the ay subtype, it was 0.1 U/mL. The detection limit for 10 HBV mutant samples was 0.5 U/mL. In 165 cases where ELISA tested negative but HBV DNA tested positive, CMIA detected 5 HBsAg-positive samples. This study evaluated the performance of the Wantai CMIA in screening for HBsAg among blood donors. The results demonstrate outstanding performance of CMIA in both clinical trials and performance assessments, detecting all true positive samples with a sensitivity of 100%. It exhibits excellent concordance with the two ELISA assays. Of particular note is its superiority in early detection of HBsAg in the screening of early-stage hepatitis B infections, reducing the window period compared to ELISA. CMIA achieves a specificity exceeding 99.73% for negative blood donors, aligning with the European Union's standards for blood screening assay specificity. In summary, Wantai's CMIA displays high sensitivity and specificity in blood donor screening, making it suitable for screening blood donors in China.

Low Risk of Occult Hepatitis B Infection among Vietnamese Blood Donors

Occult hepatitis B infection (OBI) is characterized by the presence of low levels of hepatitis B virus (HBV) DNA and undetectable HBsAg in the blood. The prevalence of OBI in blood donors in Asia ranges from 0.013% (China) to 10.9% (Laos), with no data available from Vietnam so far. We aimed to investigate the prevalence of OBI among Vietnamese blood donors. A total of 623 (114 women and 509 men) HBsAg-negative blood donors were screened for anti-HBc and anti-HBs by ELISA assays. In addition, DNA from sera was isolated and nested PCR was performed for the HBV surface gene (S); a fragment of the S gene was then sequenced in positive samples. The results revealed that 39% (n = 242) of blood donors were positive for anti-HBc, and 70% (n = 434) were positive for anti-HBs, with 36% (n = 223) being positive for both anti-HBc and anti-HBs. In addition, 3% of blood donors (n = 19) were positive for anti-HBc only, and 34% (n = 211) had only anti-HBs as serological marker. A total of 27% (n = 170) were seronegative for any marker. Two of the blood donors (0.3%) were OBI-positive and sequencing revealed that HBV sequences belonged to HBV genotype B, which is the predominant genotype in Vietnam.

Mutations in the HBV PreS/S gene related to hepatocellular carcinoma in Vietnamese chronic HBV-infected patients

Background

Chronic hepatitis B virus (CHB) infection is a major health problem and leading cause of hepatocellular carcinoma (HCC) worldwide. Several point and deletion mutations on the PreS/S gene have been intensively considered associated with HCC. This study aimed to describe the characteristics of HBV PreS/S mutations in Vietnamese CHB-infected patients and their association with HCC.

Methods

This cross-sectional study was conducted from 02/2020 to 03/2021, recruited Vietnamese CHB-infected patients with HBV-DNA >3 log₁₀-copies/mL and successful PreS/S gene sequencing. Mutations were detected by direct Sanger sequencing.

Results

247 CHB-infected patients were recruited, characterized by 68.8% males, 54.7% HBV genotype B, 57.5% HBeAg positive, 23.1% fibrosis score ≥F3 and 19.8% HCC. 61.8% amino acid replacements were detected throughout the PreS1/PreS2/S genes. The most common point-mutations included N/H51Y/T/S/Q/P (30.4%), V68T/S/I (44.9%), T/N87S/T/P (46.2%) on PreS1 gene; T125S/N/P (30.8%), I150T (42.5%) on PreS2 gene; S53L (37.7%), A184V/G (39.3%), S210K/N/R/S (39.3%) on S gene. The rates of case(s) with any point-mutation on the Major Hydrophylic Region (MHR) and the "a" determinant region were 63.6% and 39.7%, respectively. Most of S point-mutations were presented with low rates such as T47A/E/V/K (9.3%), P120S/T (8.5%), G145R (2%). On multivariable analysis, males (OR = 4.51, 95%CI 1.78–11.4, p = 0.001), age≥40 (OR = 5.5, 95%CI 2.06–14.68, p = 0.001), W4P/R/Y on PreS1 (OR = 11.56, 95%CI 1.99–67.05, p = 0.006) and 4 S point-mutations as: T47A/E/V/K (OR = 3.67, 95%CI 1.19–11.29, p = 0.023), P120S/T (OR = 3.38, 95%CI 1.09–10.49, p = 0.035), S174N (OR = 29.73, 95%CI 2.12–417.07, p = 0.012), P203R (OR = 8.45, 95%CI 1.43–50.06, p = 0.019) were associated with HCC.

Conclusions

We detected 61% amino acid changes on PreS/S regions in Vietnamese CHB patients. One point-mutation at amino acid 4 on PreS1 gene and 4 point-mutations at amino acids 47, 120, 174, and 203 on S gene were associated with HCC. Further investigations are recommended to further clarify the relationship and interaction between mutations in HBV genome and HCC progression.

A hook-effect-free homogeneous light-initiated chemiluminescence assay: is it reliable for screening and the quantification of the hepatitis B surface antigen?

Background

Hepatitis B virus (HBV) infection remains a threat to global public health. As a hallmark of HBV infection, hepatitis B surface antigen (HBsAg) has been used to screen for HBV infection for decades, and quantitative assays are also being clinically rejuvenated to predict the disease outcome and monitor the antiviral response. Herein, we developed and evaluated a hook-effect-free homogeneous quantitative HBsAg assay based on the light-initiated chemiluminescence immunoassay (LICA).

Methods

A hook-effect-free LICA algorithm was established by measuring the relative light units (RLUs) of two time points during the immunoreaction. The precision was assessed using low- and high-level controls. Consecutive clinical serum samples were tested using the LICA and Abbott Architect assay; samples producing inconsistent results were retested using supplementary assays including the HBsAg neutralization, HBV DNA, and Roche Elecsys HBsAg assays for further confirmation. The consistency, sensitivity, specificity, and positive and negative predictive values (PPV and NPV) were calculated. For the quantitative results, the correlation was analyzed. The coverage of different genotypes and mutations by the LICA was evaluated. Moreover, serial on-treatment and follow-up samples from chronic hepatitis B patients were also measured using the two assays.

Results

The LICA had better within-run and within-laboratory precisions than the Architect assay. In total, 5,176 clinical samples were tested. The two assays showed a consistency of 99.63%. The LICA showed greater specificity (99.95% vs. 99.77%) and PPV (99.75% vs. 98.77%) than the Architect assay, whereas the Architect assay showed greater sensitivity (100.00% vs. 99.01%) and NPV (100.00% vs. 99.82%). The two assays displayed an excellent correlation independent of genotypes and mutations. The LICA hook-free algorithm recognized 100% of the underestimated results. Furthermore, similar HBsAg dynamics were demonstrated using the LICA and Architect HBsAg assay.

Conclusions

The hook-free LICA provides a reliable tool for screening for HBV infection and quantifying HBsAg.

Molecular epidemiology of hepatitis B virus mutants associated with vaccine escape, drug resistance and diagnosis failure

The massive implementation of the vaccine and antiviral agents against hepatitis B virus (HBV), targeting the envelope and viral polymerase genes, induces a selection pressure that might lead to the emergence of variants that impair the effectiveness of the vaccine, diagnostic methods and antiviral therapy. The aim of this study was to evaluate the prevalence of HBV vaccine escape mutants (VEMs), diagnostic failure mutants (DFMs) and treatment resistance mutants (ARMs) among individuals from Buenos Aires, Argentina. HBV surface antigen and polymerase sequences obtained from serum samples of 530 HBV-infected individuals were analysed. Samples belonged to genotypes A (28.1%), D (13.6%) and F (58.3%). VEMs, DMFs and ARMs were present in 40 (7.5%), 57 (10.7%) and 27 (5.1%) samples within the studied population. Additionally, eight nonpreviously reported VEMs and nine DFMs were identified. VEMs and DFMs were biased by genotype, being higher in genotype D (33.3% and 33.3%) compared to genotype A (6% and 17.4%) and genotype F (2.3% and 2.3%) (P > 0.001). On the contrary, there was no association between the presence of ARMs and HBV genotype (P = 0.324). VEMs, DFMs and ARMs create public health concerns. The current study provided valuable information about mutants in surface antigen and polymerase in HBV-infected patients from Argentina where HBV-F is the most prevalent genotype. Consequently, it constitutes an important reference for Latin American clinicians in order to optimize the management of HBV-infected patients.