Detection of IgM to hepatitis B core antigen in a reductant containing, chemiluminescence assay

Sensitivity and specificity of Anti-HBc screening assays--which assay is best for blood donor screening?

Compared to HIV and hepatitis C virus, the residual infectious risk of hepatitis B virus (HBV) posed by blood products is about 10 times higher. In addition to HBsAg testing, screening for anti-HBc was recommended by the German Advisory Committee Blood in March 2005. Prevalence of anti-HBc in German blood donors was investigated at five test sites located in different geographic regions. In total, 12,000 blood donors were screened for anti-HBc by PRISM HBcore, and a statistically representative number of these were tested with Abbott Murex anti-HBc total, bioMérieux Hepanostika anti-HBc uniform, Bio-Rad Monolisa anti-HBc PLUS and Dade Behring Enzygnost anti-HBc. Anti-HBc repeat reactive samples were tested for anti-HBs, anti-HBe and HBV DNA by individual donation NAT. The mean prevalence of anti-HBc was 1.75% in donors that had not been tested for anti-HBc in the past. The percentage of anti-HBs in anti-HBc repeat reactive donors was 93.7%. Samples that were additionally reactive for anti-HBe were anti-HBc reactive in all tested assays. The sample to cut-off (S/Co) values for anti-HBc were lower (competitive assays) in samples that were also positive for anti-HBe, when compared to samples that were only anti-HBc reactive. Most commercially available anti-HBc assays provide sufficient sensitivity for routine screening purposes, and lacking specificity is no longer a serious issue for most of them. Assay differences were recognized for samples that were anti-HBc only reactive. The overall loss of 1.75% of positive testing donors can be significantly reduced to 0.45% by implementation of re-entry procedures for donors with an anti-HBs titre of over 100 IU/l and negative by sensitive ID-NAT.

Performance of an algorithm for the reentry of volunteer blood donors deferred due to false-positive test results for antibody to hepatitis B core antigen

BACKGROUND

Blood donor testing for antibody to hepatitis B core antigen (anti-HBc) has been used in the United States for more than 20 years as a surrogate to prevent transmission by transfusion of non-A, non-B hepatitis, as a human immunodeficiency virus surrogate, and to reduce transmission of hepatitis B virus (HBV). Nonspecific anti-HBc assays have caused deferral of hundreds of thousands of otherwise qualified donors. A more specific anti-HBc test and a sensitive HBV DNA test should permit donor reentry after false-positive anti-HBc.

STUDY DESIGN AND METHODS

A total of 1324 otherwise eligible volunteer donors, deferred for anti-HBc reactivity on more than one occasion, were recruited from four collection facilities. They were tested using a licensed, more specific anti-HBc test, a licensed hepatitis B surface antigen (HBsAg) test, and a licensed HBV DNA assay with a 95 percent limit of detection of not more than 10 copies per mL.

RESULTS

From 11 to 32 percent of donors contacted by participating sites entered the study. Overall, 488 (37%) of the donors were negative on the more specific anti-HBc test. The proportion of putative false-positive samples varied according to the test responsible for the original deferral. A single donor, negative for the presence of anti-HBc and HBsAg, was positive for the presence of HBV DNA in one of three replicates. Repeat testing of this donor 10 months later was negative for the presence of all markers of HBV infection, and the donor had a history of HBV vaccination with documented postimmunization anti-HBs seroconversion 10 years before her anti-HBc deferral, and was considered HBV DNA false positive.

CONCLUSION

These data support reentry of donors with false-positive anti-HBc results on the relatively nonspecific assays that have been in use in the United States for more than 20 years.

Rapid Assay of Trace Immunoglobulin M by a New Immunonanogold Resonance Scattering Spectral Probe

Nanogold, 8 nm in size, was used to label goat antihuman immunoglobulin M (GIgM) to obtain a new immunonanogold resonance scattering (RS) probe (Au-GIgG) for quantitation of trace immunoglobulin M (IgM). The Au-GIgG combined with IgM to form nanogold-labeled immunocomplex causes the RS intensity at 580 nm to be enhanced, in pH 4.49 KH2PO 4-Na2HPO4 buffer and in the presence of polyethylene glycol 6000. The enhanced RS intensity at 580 nm (ΔI580 nm) is proportional to the IgM concentration in the range of 1.5 to 2000 ng/mL, with a lower detection limit of 0.98 ng/mL. The immunonanogold RS assay was used to assay IgM in serum samples, with sensitivity, selectivity, and simplicity. ( Journal of Biomolecular Screening 2008:302-308)

Performance characteristics of microparticle enzyme and chemiluminescence immunoassays for measurement of anti-HBc immunoglobulin M in sera of patients with HBeAg-negative chronic hepatitis B virus infection

The IMx, AxSym, and Architect immunoglobulin M anti-HBc assay systems for detecting hepatitis B virus e antigen-negative chronic hepatitis B virus infection were compared. Despite good intra- and interassay coefficients of variation, significantly different values and low correlation (overestimation by AxSym and underestimation by Architect) were observed. Association and cutoff values for distinguishing patients with viral replication should be established for all methods.

Nanoparticle-based electrochemical detection of hepatitis B virus using stripping chronopotentiometry

A selective and sensitive gold nanoparticle-based electrochemical method for detection of hepatitis B virus DNA sequences was used. This method relies on the hybridization of amplified hepatitis B virus DNA strands with probes that are extended on paramagnetic beads. After separation of noncomplementary sequences, hybridized magnetic beads were treated with streptavidin-modified gold followed by silver enhancement. High selectivity and high sensitivity were obtained using electrochemical stripping detection of silver ions that were deposited on gold nanoparticles. With a signal/noise ratio of approximately 4.6, the detection limit was estimated to be 0.7ng/ml.

Analytical performance of and real sample analysis with an HBV gene visual detection chip

A novel hepatitis B virus (HBV) gene detection chip has been developed. The HBV-specific probes immobilized on glass slides were hybridized with polymerase chain reaction (PCR) products of different serum samples. The hybridization signal can be easily visualized upon a sandwich assay with nanoparticle amplification. The analytical performance (e.g., specificity, sensitivity, and accuracy) of this method has been evaluated. The chip-based detection method possesses a greater sensitivity and a better reproducibility than some of the conventional immunological or molecular biological methods (e.g., enzyme-linked immunosorbent assay, ELISA) and is simple, cost-effective, and highly selective.