Anti-HCV Core Protein Monoclonal antibody, Clone A1852

Background The study aimed to evaluate a fully automated chemiluminescent immunoassay and compared it with a quantitative RNA assay and anti-HCV assay to verify the utility of this automated Ag assay as an alternative method for hepatitis C diagnosis. Methods A total of 229 serum samples previously tested for anti-HCV concentrations by the Architect Anti-HCV assay, were selected for HCV RNA testing by real time RT-PCR kit (Shanghai ZJ Bio-Tec Co., Ltd) and 125 specimens were tested for HCV Ag by the Architect HCV core Antigen kit. Results The log(10) HCVAg and HCV RNA concentrations were highly correlated [r=0.834); with HCV RNA as the comparator test, HCVAg had 100% specificity, 100% positive predictive value (PPV) and 94.8% sensitivity. We found 1pg/mL of total HCV core Ag is equivalent to approximately 6607HCV RNA international units (IU)/mL. Receiver operator characteristic curve analysis showed that the area under the curve of HCV core Ag (0.989) was greater than HCV Ab (0.871). HCV Ag concentrations and RNA-to-Ag ratio of the groups for HCV RNA concentrations 10(5) and >10(5)IU/mL were both significantly different from each other (P<0.05). Conclusion The Architect HCV core Ag assay may be an alternative method for hepatitis C diagnosis, performed on the same analytical platform and sample as the anti-HCV assay, shortening the diagnostic window period, demonstrating good correlation with HCV RNA assay with high specificity and positive predictive value.

Previous studies showed that monoclonal immunoglobulins G (IgGs) of "monoclonal gammopathy of undetermined significance" (MGUS) and myeloma were hyposialylated, thus presumably pro-inflammatory, and for about half of patients, the target of the monoclonal IgG was either a virus-Epstein-Barr virus (EBV), other herpes viruses, hepatitis C virus (HCV)-or a glucolipid, lysoglucosylceramide (LGL1), suggesting antigen-driven disease in these patients. In the present study, we show that monoclonal IgAs share these characteristics. We collected 35 sera of patients with a monoclonal IgA (6 MGUS, 29 myeloma), and we were able to purify 25 of the 35 monoclonal IgAs (6 MGUS, 19 myeloma). Monoclonal IgAs from MGUS and myeloma patients were significantly less sialylated than IgAs from healthy volunteers. When purified monoclonal IgAs were tested against infectious pathogens and LGL1, five myeloma patients had a monoclonal IgA that specifically recognized viral proteins: the core protein of HCV in one case, EBV nuclear antigen 1 (EBNA-1) in four cases (21.1% of IgA myeloma). Monoclonal IgAs from three myeloma patients reacted against LGL1. In summary, monoclonal IgAs are hyposialylated and as described for IgG myeloma, significant subsets (8/19, or 42%) of patients with IgA myeloma may have viral or self (LGL1) antigen-driven disease.