A Novel Antigen Detection Immunoassay for Field Diagnosis of Hepatitis C Virus Infection

• Published in: Journal of immunoassay & immunochemistry 2003, Vol.24 (4), p.395-407
• Main Authors: Attallah, Abdelfattah M., Ismail, Hisham, Tabll, Ashraf A., Shiha, Gamal E., El-Dosoky, Ibrahim
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Diagnosis; Diagnosis, Differential; Dot-ELISA; Egypt - epidemiology; Enzyme-Linked Immunosorbent Assay - methods; HCV; HCV-NS4 antigen; Hepatitis C; Hepatitis C - diagnosis; Hepatitis C - epidemiology; Hepatitis C Antibodies - immunology; Hepatitis C Antigens - analysis; Hepatitis C Antigens - blood; Hepatitis C Antigens - immunology; Hepatitis C virus; Humans; Immunoglobulin G - immunology; Male; Mass Screening - methods; Middle Aged; Polymerase Chain Reaction; Recombinant Proteins - analysis; RNA, Viral - blood; Sensitivity and Specificity; Serum; Viral Nonstructural Proteins - analysis; Viral Nonstructural Proteins - blood; Viral Nonstructural Proteins - immunology
• ISSN: 1532-1819; 1532-4230
• DOI: 10.1081/IAS-120025777

The limitations of dominant methods-based on the detection of anti-HCV antibodies or HCV viremia currently used for the diagnosis of HCV infection enhance efforts to have a rapid, simple, sensitive, and specific alternative diagnostic approach to detect viral antigens. A highly reactive IgG antibody was raised to HCV-NS4 recombinant antigen. The produced antibody showed no cross-reactivity with the other HCV structural and nonstructural recombinant antigens (C1 + 2, C3 + 4, E2/NS1, NS3, NS5). The well established ELISA technique was adapted to detect the new target HCV-NS4 antigen in serum samples. Extremely high agreement was found between the results of ELISA and qualitative detection of HCV-RNA, using a RT-PCR test as a gold standard for the diagnosis of HCV infection. Based on these encouraging results, a novel enzyme immunoassay; dot-ELISA was developed for rapid (˜5 min) and simple qualitative detection of the target HCV antigen in serum. The developed method detected the HCV target antigen in 95% of serum samples from HCV infected individuals, with a specificity of 97% using sera of noninfected individuals in comparison with PCR test. The antigen detection method showed high predictive values of positive (99%) and negative (90%). Moreover, the dot-ELISA could detect the HCV target antigen in sera negative for anti-HCV Abs, but positive for HCV-RNA, and in sera of HCV infected individuals with low viremia, as well as those with high viremia, using quantitative RT-PCR. Accordingly, the developed highly sensitive and specific HCV antigen detection method could be applied for mass screening of HCV infection.