Multicenter performance evaluation of the Elecsys HCV Duo immunoassay.

BACKGROUND: The diagnostic accuracy of the Elecsys® HCV Duo antigen-antibody combination immunoassay (Roche Diagnostics GmbH) was evaluated for the detection of hepatitis C virus (HCV) infection, versus commercially available comparators. METHODS: This multicenter study (August 2020-March 2021) assessed the specificity of the Elecsys HCV Duo immunoassay and comparator assays in blood donor and routine clinical laboratory samples; sensitivity was determined in confirmed HCV-positive samples and seroconversion panels. The Elecsys HCV Duo immunoassay was compared with the Monolisa HCV Ag-Ab ULTRA V2, Murex HCV Ag/Ab Combination and ARCHITECT HCV Ag assays, as well as nucleic acid testing (NAT). The antibody (anti-HCV) module of the Elecsys HCV Duo immunoassay was compared with the Elecsys Anti-HCV II, Alinity s Anti-HCV, ARCHITECT Anti-HCV and RIBA HCV 3.0 SIA assays. RESULTS: The specificity of the Elecsys HCV Duo immunoassay was 99.94% (95% confidence interval [CI], 99.89-99.97) and 99.92% (95% CI, 99.71-99.99) in blood donor (n = 20,634) and routine clinical laboratory samples (n = 2531), respectively. The specificity of the Elecsys HCV Duo immunoassay was similar or better than comparator assays. The sensitivity of the Elecsys HCV Duo immunoassay in confirmed HCV-positive samples (n = 257) was 99.6%. In seroconversion panels, the Elecsys HCV Duo immunoassay detected infections earlier (2.2-21.9 days) than all but one of the comparator assays and detected HCV 1.8 days later than NAT. CONCLUSIONS: The Elecsys HCV Duo immunoassay shows high diagnostic accuracy, reduces the diagnostic window, and could be used when NAT is not possible.

Chaperone-aided in vitro renaturation of an engineered E1 envelope protein for detection of anti-Rubella virus IgG antibodies.

The envelope glycoproteins of Rubella virus, E1 and E2, mediate cell tropism, and E1 in particular plays a pivotal role in the fusion of the virus with the endosomal membrane. Both are the prime targets of the humoral immune response. Recombinant variants of the E1 ectodomain as well as E1 antigen preparations from virus lysates are commonly used to detect anti-Rubella immunoglobulins in human sera. Hitherto, recombinant E1 for diagnostic applications has been produced chiefly in eukaryotic expression systems. Here, we report the high-yield overproduction of an engineered E1 ectodomain in the Escherichia coli cytosol and its simple and convenient renaturation into a highly soluble and immunoreactive conformation. C-Terminal fusion to one or two units of the E. coli chaperone SlyD enhances expression, facilitates in vitro refolding, and improves the overall solubility of Rubella E1. As part of this fusion protein, the E1 ectodomain fragment of residues 201-432 adopts an immunoreactive fold, providing a promising tool for the sensitive and specific detection of anti-E1 IgG in Rubella serology. Two disulfide bonds in the membrane-adjacent part of the E1 ectodomain are sufficient to generate conformations with a high and specific antigenicity. The covalently attached chaperone modules do not impair antibody recognition and binding of Rubella E1 when assessed in a heterogeneous immunoassay. SlyD and related folding helpers are apparently generic tools for the expression and refolding of otherwise unavailable proteins of diagnostic or medical importance.