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One-step HCV diagnostic shows 99% specificity, 100% sensitivity

A novel one-step hepatitis C virus antigens enzyme immunoassay showed 99% specificity and 100% sensitivity in differentiating resolved HCV from viremic HCV, according recent findings published in Hepatology.

“The present study introduced a novel, highly specific and sensitive HCV antigens enzyme immunoassay (HCV-Ags EIA) test that is well-correlated to HCV replication as determined by serum HCV RNA real-time polymerized chain reaction (RT-PCR),” Ke-Qin Hu, MD, and Wei Cui, MD, both in the division of hepatology at the University of California, Irvine School of Medicine, and colleagues wrote. “Based on the literature, its sensitivity is superior to those reported HCV core antigen (HCVcAg) assays. Additionally, our HCV-Ags EIA offers significantly improved specificity by excluding sample denaturation, and provides a highly specific and reliable one-step test to screen and diagnose viremic HCV (V-HCV) infection.”

Ke-Qin Hu

Current HCV diagnostics require two steps: an anti-HCV screening test and an HCV RNA RT-PCR to confirm V-HCV. HCVcAg assays require only one step, but they have low sensitivity and specificity.

Hu and Cui assessed the sensitivity and specificity of a novel one-step HCV-Ags EIA by using 365 serum specimens, 189 of which had V-HCV. The assay works by detecting the presence of the HCV nonstructural proteins 3, 4b and 5a as well as HCV core antigen protein.

The researchers found that serum sample denaturation decreases test specificity, which was a novel finding. This suggests that denaturation should not be used in any HCV antigen assay. Using sample non-denaturation, the HCV-Ags EIA showed 99% specificity and 100% sensitivity compared with serum anti-HCV and HCV RT-PCR results. The lowest levels of detection were equivalent to serum HCV RNA levels between 150 and 250 IU per mL.

The researchers concluded that their novel assay can reliably differentiate V-HCV from resolved HCV when using non-denaturation of serum samples.

“Sample non-denaturation is the only way to assure the feasibility to utilize HCV-Ags assays to specifically diagnose V-HCV infection,” the researchers wrote. “Additionally, eliminating sample denaturation will make this type of test more time-saving and simple.” – by Will Offit

Disclosure: Hu reports being on the speakers bureau for AbbVie, Gilead Sciences and Janssen Therapeutics as well as being a consultant for DiligenMed Inc. Cui reports no relevant financial disclosures.