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

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.

Versatile performance edges of HBsAg Next assay in diagnosis and therapeutic monitoring of HBV infection

BACKGROUND

HBsAg Next assay (HBsAgNx) claims improved detection of HBsAg. The aim was to investigate its performance in ascertaining HBsAg loss, ability to detect HBsAg in various phases of HBV infection, specificity and its amenability to in-house neutralization.

METHODS

Analytical sensitivity was investigated using NIBSC standard (3rd WHO-IS). For clinical performance, out of 91,962 samples tested for HBsAg (Qual-II), 512 samples consisting of 170 cases with evidence of HBsAg loss during treatment (n = 116) and without treatment (n = 54), acute-hepatitis B (n = 90) and acute exacerbation of chronic-hepatitis B (n = 41), acute-hepatitis A (n = 24) and acute-hepatitis E (n = 9) positive, HIV-1 positive (n = 20), non-HBV, HAV and HEV related acute-hepatitis (n = 81) and HBsAg prozone (n = 14) as well as in-house neutralization (n = 63) were included.

RESULTS

The calculated limit of detection (LOD) was 0.004 IU/mL. Of the 170 patients with apparent HBsAg loss, 18/116 (15.5%) among treated and 15/54 (27.7%) with spontaneous clearance were positive in HBsAgNx (p < 0.0001). Additionally, it detected HBsAg in 12/95 (12.6%) and 6/34 (17.6%) patients who were HBV DNA negative in treatment experienced and spontaneous clearance groups respectively (p < 0.001). The specificity of HBsAgNx was comparable to HBsAg Qual-II. The signal-intensity of HBsAgNx was significantly higher than HBsAg Qual-II across various phases of HBV infection and prozone samples.

CONCLUSION

HBsAgNx significantly enhanced the accuracy of HBsAg detection without compromising the specificity in ascertaining HBsAg loss. The performance was superior in various phases of HBV infection including samples that exhibited prozone effect. Furthermore, it is amenable to cost-effective in-house neutralization to confirm low HBsAg levels.

Cost-Effective In-House Neutralization Assay for the Confirmation of HBeAg

BACKGROUND & AIM

Hepatitis B virus-e-antigen (HBeAg) is an affordable viral marker to assess viral replication kinetics and response to antiviral therapy. In the absence of confirmatory assays, discrepant or false-positive HBeAg results are resolved by screening for other HBV markers. We standardized an in-house HBeAg neutralization assay (HBeAg-NT) to confirm HBeAg in clinical samples.

METHODS

The performance and reliability of this assay were evaluated by first WHO International Standard for HBeAg (first WHO-IS HBeAg) from Paul Ehrlich Institute and clinical samples (n = 150) from chronic HBV carriers. Of these, 71 HBeAg-positive sera were used for HBeAg-NT.

RESULTS

Concentrations spanning 0.25-10 U of first WHO-IS HBeAg and clinical samples (S/Co ranges from 1.00 to 10.00) were neutralized completely in the HBeAg-NT.

CONCLUSIONS

HBeAg-NT is a simple, cost-effective, and reliable direct approach to confirm HBeAg in clinical samples which precludes the need for screening additional HBV markers in low resource settings.

Detection of hepatitis B virus infection: A systematic review

AIM: To review published methods for detection of hepatitis B virus (HBV) infection.

METHODS: A thorough search on Medline database was conducted to find original articles describing different methods or techniques of detection of HBV, which are published in English in last 10 years. Articles outlining methods of detection of mutants or drug resistance were excluded. Full texts and abstracts (if full text not available) were reviewed thoroughly. Manual search of references of retrieved articles were also done. We extracted data on different samples and techniques of detection of HBV, their sensitivity (Sn), specificity (Sp) and applicability.

RESULTS: A total of 72 studies were reviewed. HBV was detected from dried blood/plasma spots, hepatocytes, ovarian tissue, cerumen, saliva, parotid tissue, renal tissue, oocytes and embryos, cholangiocarcinoma tissue, etc. Sensitivity of dried blood spot for detecting HBV was > 90% in all the studies. In case of seronegative patients, HBV DNA or serological markers have been detected from hepatocytes or renal tissue in many instances. Enzyme linked immunosorbent assay and Chemiluminescent immunoassay (CLIA) are most commonly used serological tests for detection. CLIA systems are also used for quantitation. Molecular techniques are used qualitatively as well as for quantitative detection. Among the molecular techniques version 2.0 of the CobasAmpliprep/CobasTaqMan assay and Abbott’s real time polymerase chain reaction kit were found to be most sensitive with a lower detection limit of only 6.25 IU/mL and 1.48 IU/mL respectively.

CONCLUSION: Serological and molecular assays are predominant and reliable methods for HBV detection. Automated systems are highly sensitive and quantify HBV DNA and serological markers for monitoring.

Universal screening versus universal precautions in the context of preoperative screening for HIV, HBV, HCV in India

In the Indian context, there is a convention of doing pre-operative screening for HIV, hepatitis B virus and hepatitis C viruses for all patients as a routine pre-intervention investigation. This approach is justified in some instances in the best interest of the patient. However, as routine screening is not the standard care internationally and as there is a significant divergence of views about the merits and demerits of this practice, this issue needs to be debated in a rational manner with an evidence-based approach. The present article is authored by a surgeon and a microbiologist from a new cancer care centre in eastern India, who has attempted to address this contentious issue. The various available options have been explored, and advantages and disadvantages of the different approach have been discussed. An algorithm for infection prevention and control has been presented so that surgeons and medical microbiologists could manage infection control challenges satisfactorily.