Discordant diagnostic results due to a hepatitis B virus T123A HBsAg mutant

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.

Molecular and serological characterization of occult hepatitis B among blood donors in Maputo, Mozambique

BACKGROUND

Occult hepatitis B virus (HBV) - characterized by the absence of detectable HBsAg in the presence of HBV DNA - represents a potential threat for blood safety.

OBJECTIVES

This study was conducted with the aim to investigate the serological and molecular characterization of occult HBV infection (OBI) among blood donors in Mozambique.

METHODS

1,502 blood donors were tested for HBsAg. All HBsAg-negative individuals were tested for HBV DNA. Antibodies against HBV core, surface and HBe antigen (anti-HBc, anti-HBs, HBeAg) were measured in HBV DNA positive individuals.

FINDINGS

1435 serum samples were HBsAg negative and 16 positive for HBV DNA, 14 confirmed to have OBI, corresponding to a frequency of 0.98%. Of the 14 OBI infections identified, 13/14 (92.8%) were positive for anti-HBc, 4/14 (28.5%) for anti-HBs, and no samples were reactive for HBeAg. Of the 14 OBI cases, nine samples (64.2%) were sequenced for the S/P region. Eight samples (88.9%) belonged to genotype A1 and one (11.1%) to genotype E. One escape mutation (T123A) associated with OBI and various amino acid substitutions for genotype A1 and E were observed.

MAIN CONCLUSIONS

Our results show the importance of using nucleic acid amplification test to detect occult hepatitis B infection in blood donors in Mozambique.

Analysis of HBsAg mutations in the 25 years after the implementation of the hepatitis B vaccination plan in China

Since 1992, China has promoted hepatitis B vaccination. Concurrently, during this period, increasing use of immunoglobulins and nucleoside analogues might have exerted selective pressure on the hepatitis B virus (HBV) S gene, driving mutations in the HBsAg and changed the subtype. Using the National Center for Biotechnology Information database, we obtained gene sequence information for HBV strains from China and analysed changes in HBsAg subtypes and substitution mutations in HBsAg in 5-year intervals over 25 years to identify potential challenges to the prevention and treatment of hepatitis B. Most HBV sequences from China were genotype C (1996/2833, 70.46%) or B (706/2833, 24.92%). During the implementation of hepatitis B vaccination (recombinant hepatitis B vaccine was subgenotype A2 and HBsAg subtype adw2), the proportion of subtypes ayw1 and adw3 in genotype B and ayw2 in genotype C increased over the programme period. The overall mutation rate in HBsAg tended to decrease for genotype B, whereas, for genotype C, the rate increased gradually and then decreased slightly. Moreover, the mutation rate at some HBsAg amino acid sites (such as sG145 of genotype B and sG130 and sK141 of genotype C) is gradually increasing. HBV strains with internal stop codons of HBsAg (e.g., sC69*) and additional N-glycosylation (e.g., sG130N) mutations should be studied extensively to prevent them from becoming dominant circulating strains. The development of HBV vaccines and antiviral immunoglobulins and use of antiviral drugs may require making corresponding changes.

Prediction value of serum HBV large surface protein in different phases of HBV infection and virological response of chronic hepatitis B patients

BACKGROUND

Serum HBV large surface protein (HBV-LP) is an envelope protein that has a close relationship with HBV DNA level. This study is to explore the prediction value of HBV-LP in different phase of HBV infection and during antiviral therapy in chronic hepatitis B (CHB) patients.

METHODS

A retrospective study was conducted in 2033 individuals, which included 1677 HBV infected patients in different phases and 356 healthy controls. HBV-LP, HBV serum markers and HBV DNA were detected by ELISA, CMIA and qRT-PCR, respectively. 85 CHB patients receiving PegIFNα or ETV were divided into virological response (VR) and partial virological response (PVR). The dynamic changes of HBV DNA and HBV-LP were observed.

RESULTS

The level of HBV-LP in 2033 individuals was shown as: HBeAg-positive hepatitis > HBeAg-positive infection > HBeAg-negative hepatitis > HBeAg-negative infection > healthy controls. HBV-LP was positive in all patients whose HBV DNA > 1.0E + 06 IU/ml. When HBsAg was <0.05 IU/ml or >1000 IU/ml, HBV DNAs were all negative if HBV-LP < 1.0 S/CO. When HBsAg was between 0.05 IU/ml and 1000 IU/ml, the consistency of HBV-LP with HBV DNA was 100% in case of HBV-LP > 4.0 S/CO in HBeAg-positive patients and HBV-LP > 2.0 S/CO in HBeAg-negative ones. During antiviral therapy, baseline HBV-LP was lower in VR patients than that in PVR patients. The optimal cut-off points to predict VR by baseline HBV-LP were 32.4 and 28.6 S/CO for HBeAg-positive and HBeAg-negative hepatitis patients, respectively.

CONCLUSIONS

HBV-LP may be a useful marker for distinguishing the different phases of HBV infection. Moreover, baseline HBV-LP level can be used for predicting VR of CHB patients.