A study based on four immunoassays: Hepatitis C virus antibody against different antigens may have unequal contributions to detection

Abstract

Background All commercial Hepatitis C virus antibody (anti-HCV) assays use a combination of recombinant antigens to detect antibody response. Antibody responses to individual antigenic regions (core, NS3/4 and NS5) used in assays have not been investigated. Methods In this study, we quantified HCV viral load, tested anti-HCV with four commercial assays (Ortho-ELISA, Murex-ELISA, Architect-CMIA and Elecsys-ECLIA) in 682 plasma specimens. In antigenic region ELISA platform, microwells were coated with three antigens: core (c22-3), NS3/4 (c200) and NS5 individually. The signal-to-cutoff (S/Co) values of different assays, and antibody responses to individual antigens were compared. The specimens were divided into HCV RNA positive group, anti-HCV consistent group, and anti-HCV discrepant group. Results Anti-core and anti-NS3/4 were simultaneously detected in 99.2% of HCV RNA positive specimens and showed great consistency with total anti-HCV signals. Responses to the core region were more robust than those to the NS3/4 region in anti-HCV consistent group (p < 0.001). Anti-NS5 only occurred in companying with responses to the core and NS3/4 antigens, and failed to affect the final anti-HCV positive signals. In anti-HCV discrepant group, 39.0% of positive signals could not be traced back to any single antigenic region. Conclusion Antibody responses to the core and NS3/4 antigens were stronger, whereas responses to the NS5 antigen were the weakest, indicating that individual antigenic regions played different roles in total anti-HCV signals. This study provides an impetus for optimizing commercial anti-HCV assays.

A rare monoclonal antibody discovery based on indirect competitive screening of a single hapten-specific rabbit antibody secreting cell

“…Several direct one-step assays focused on determining the affinity of the secreted antibodies toward the coated antigens have been applied to antibody production based on nanowell for hepatitis C virus 37 and ovalbumin. 38 However, these direct assays are not suitable for precise hapten-specific ASC selection owing to the need for at least two steps to completely identify the secreted hapten-specific antibody, including the first step of identification of the binding to coating antigen and the second step of identification of binding to the target analyte.…”

A new double-antigen sandwich test based on the light-initiated chemiluminescent assay for detecting anti-hepatitis C virus antibodies with high sensitivity and specificity

“…During the early stage of infection, people may develop different levels of antibodies due to varied immunogenicity of HCV antigens and different reactivity of individuals. The detection capability for a given anti-HCV assay is highly associated with the antigen configuration of the reagent kit because each HCV antigen may have unequal contribution to antibody detection (Warkad et al, 2019;Jiang et al, 2021). Both WHO and US CDC guidelines on HCV tests recommend that the diagnosis of infection is initially detected with a serological screening of anti-HCV and followed by a reflexive PCR test of HCV RNA (Centers for Disease Control and Prevention, 2013;World Health Organization, 2017b).…”

“…Undetectable HCV RNA may indicate a prior resolved infection in which the virus has been eradicated from the circulation (El Ekiaby et al, 2015). Inconsistency of detection performance in the same cohort may be explained by the specific antigen configuration of different anti-HCV assays (Warkad et al, 2019;Jiang et al, 2021). An additional one that was misdiagnosed on Architect ® with an entirely nonreactive S/Co (0.05) was well-reactive (12.11) on LiCA ® and confirmed to be positive (857 IU/mL) by HCV RNA.…”

Glycylglycine promotes the solubility and antigenic utility of recombinant HCV structural proteins in a point-of-care immunoassay for detection of active viremia

“…The color intensity was measured, and signal-to-cutoff (S/Co) values were calculated to measure the concentration of specific antibodies. Sera with S/Co values ≥ 1 were considered reactive [ 52 ]. Positive and negative patients’ sera were classified according to the determined S/Co values, and the distribution of anti-HCV antibody levels was evaluated within each group.…”