Diagnosis of hepatitis C virus (HCV) infection and laboratory monitoring of its therapy.

BACKGROUND: Just after the identification and characterization of hepatitis C virus (HCV) in 1989, tests for the detection of HCV antibodies or HCV RNA in serum were developed. The enzyme-linked immunosorbent assays (ELISAs) and confirmatory/supplemental analytical antibody tests were improved in sensitivity and specificity with the development of further generations of these assays. Application of molecular tests for detecting, quantifying, and characterization of the infecting virus became very important in management of HCV infection. OBJECTIVE AND
DESIGN: This review summarizes the assays developed for the diagnosis and management of HCV infection. Strategies for the diagnosis and monitoring with the advantages and disadvantages of the assays based on the setting and goal are discussed according to data in the literature and our experience.
RESULTS: Specific laboratory diagnostic tests for hepatitis C virus infection may be discussed under two titles: (i) Serological antibody tests which detect anti-HCV in serum or plasma; (ii) Molecular tests which detect HCV RNA genome, investigate viral load, and determine the characteristics of the genome. Strategies in different laboratory settings which screen populations with different HCV prevalences vary.
CONCLUSIONS: Anti-HCV positive result in a low-risk setting such as blood banks should be confirmed with an analytical antibody test. Then a HCV RNA test should be performed on serum of the person with a positive or indeterminate confirmatory test result. On the contrary, anti-HCV positive test result in high-risk population or a situation where HCV infection is suspected, it is likely to be true positive and confirmation with HCV RNA test will be significant. Quantitative HCV RNA test and genotyping should be performed if therapy is considered.