Molecular testing in the diagnosis and management of hepatitis C virus infection.

OBJECTIVES: To review hepatitis C virus (HCV), describe the types of molecular-based tests available for the diagnosis and management of HCV infection, and discuss the appropriate utilization of these tests. DATA SOURCES: Current information is presented from the published literature, as well as new information where available. STUDY SELECTION: A major cause of posttransfusion and community-acquired non-A, non-B hepatitis worldwide is HCV. Approximately 4 million people in the United States are infected with HCV, resulting in 8000 to 10,000 deaths annually. Because HCV is not readily cultured, in vitro molecular-based tests have been developed for use in the diagnosis and treatment of HCV-infected patients. Molecular tests include qualitative and quantitative nucleic acid amplification tests, branched DNA tests, and HCV genotyping assays. Qualitative HCV nucleic acid amplification tests are used routinely in association with serologic tests to help make a diagnosis of infection with HCV. Quantitative HCV testing and genotyping methods have been found to be valuable tools in the treatment of infected patients. A patient's pretreatment HCV viral load and the rate of virus decline during therapy have been shown to correlate with the likelihood of long-term response to antiviral therapy. Information pertaining to the genotype of HCV infecting patients has been shown to be helpful in making recommendations regarding treatment. Certain genotypes of HCV are much more responsive to therapy, allowing a shorter course of treatment.
CONCLUSIONS: Molecular tests are valuable tools for use in the diagnosis and treatment of patients infected with HCV.