An Automated Immunoblot Method for Detection of IgG Antibodies to Hepatitis C Virus: a Potential Supplemental Antibody Confirmatory Assay.

An estimated 41,200 people were newly infected with hepatitis C virus (HCV) in 2016 in the United States. Screening tests for antibodies to HCV may generate up to 32% false positivity in low-risk populations. Current Centers for Disease Control and Prevention (CDC) screening recommendations do not require confirmatory testing of a screening anti-HCV-positive test; however, confirmation is valuable for surveillance in the absence of HCV RNA testing. A recombinant immunoblot assay (RIBA) was used as a confirmatory assay for anti-HCV-reactive samples but was discontinued in 2013. Another anti-HCV confirmatory assay, INNO-LIA, is commercially available in Europe but is not approved by the Food and Drug Administration (FDA) in the United States. We report the development of an anti-HCV assay that was performed on an automated immunoblot platform using a fourth-generation HCV recombinant fusion protein. Based on testing of 70 well-characterized samples, of which 40 were HCV RNA and anti-HCV positive, 15 were HCV RNA positive/anti-HCV negative, and 15 were HCV RNA and anti-HCV negative, the specificity and sensitivity of the HCV-WES assay were 100% and 95%, respectively. Concordance between INNO-LIA and HCV-WES was determined by testing 205 HCV RNA-negative/anti-HCV-positive samples, of which 149 (72.7%) were positive by HCV-WES, while 146 (71.2%) were positive by INNO-LIA. We have shown proof of concept for the use of this test for confirmation of screened anti-HCV results. The HCV-WES assay has advantages over manual Western blot assays and INNO-LIA, including ease of use, lower cost, and reduced hands-on time.