Related Experiment Videos
[Importance of PCR in the diagnosis of hepatitis C]
F Laurent1, J S Li, L Vitvitski
1Unité de recherche sur les Hépatites, le SIDA et les rétrovirus humains (INSERM Unité 271), Lyon.
Insights
Polymerase chain reaction (PCR) precisely estimates hepatitis C virus (HCV) prevalence and aids diagnosis when antibody tests fail. PCR detects HCV RNA, confirming infectivity, monitoring treatment, and analyzing viral strains.
Area of Science:
- Hepatology
- Virology
- Molecular Diagnostics
Background:
- Non-A, non-B hepatitis (NANBH) diagnosis historically relied on less specific methods.
- Early enzyme-linked immunosorbent assays (ELISA) for anti-HCV antibodies had high false-positive rates.
- Need for more sensitive and specific diagnostic tools for hepatitis C virus (HCV).
Purpose of the Study:
- To evaluate the utility of polymerase chain reaction (PCR) for hepatitis C virus (HCV) diagnosis and management.
- To compare PCR with immunoserological tests for HCV detection.
- To explore PCR's role in various clinical scenarios and epidemiological studies.
Main Methods:
- DNA amplification via PCR to detect HCV RNA sequences.
- Comparison of PCR results with anti-HCV antibody testing (ELISA).
- Analysis of HCV RNA in serum, liver tissue, and epidemiological samples.
Main Results:
- PCR directly detects HCV RNA, confirming infectivity in antibody-positive individuals with indeterminate/negative confirmatory tests.
- Early detection of HCV RNA aids diagnosis of acute hepatitis and seronegative chronic hepatitis.
- HCV RNA detection correlates with viral replication, liver damage severity, and interferon treatment efficacy.
- PCR identified at least three distinct HCV strains in France.
- HCV RNA can be present in liver tissue without detectable viremia.
Conclusions:
- PCR is a valuable tool for precise HCV diagnosis, especially in challenging cases (acute, seronegative chronic, post-transplant).
- HCV RNA monitoring via PCR is crucial for assessing treatment response and understanding viral replication.
- PCR aids epidemiological studies, including vertical transmission, and viral genotyping.
- Limitations exist, necessitating development of simpler, rapid diagnostic tests for HCV.
Abstract:
The identification of hepatitis C virus, based on DNA amplification, gives a precise estimation of the prevalence of the most frequent agent of NANB hepatitis. The first ELISA allowing the detection of anti-HCV antibodies, had too many false positive results and required the development of more sensitive and specific assays to confirm its results. PCR, allowing the hepatitis C virus diagnosis by showing directly HCV RNA sequences, offers a complementary approach to immunoserological tests. In blood donors with anti-HCV antibodies and with indeterminate or negative confirmatory tests, the finding of HCV RNA sequences reveals serum infectivity. During acute hepatitis, the delay in the appearance of anti HCV hampers acute phase diagnosis. The early detection of HCV RNA in peripheral blood, confirms the diagnosis and opens up therapeutic possibilities. In chronic hepatitis, the diagnosis of seronegative forms may only be resolved by PCR. Moreover, the presence of HCV RNA in peripheral blood represents the only marker of on-going viral replication and coincides with the severity of liver damage. During treatment with interferon, the follow up of HCV RNA sequences makes it possible to monitor its efficacy. The search for HCV RNA sequences directly in liver tissue shows that HCV may replicate in the liver in the absence of viremia. The presence of HCV RNA in the liver and the serum of liver transplanted patients is essential for the etiological diagnosis and management of hepatitis and bone marrow failure occurring after transplantation. Epidemiological study using PCR is a major tool in documenting vertical transmission between mother and child. Finally, PCR is important for the analysis of the HCV genome. Thus, in France there are at least three main strains, one close to the US prototype, the other close to the Japanese strain, possibly responsible for a more severe illness and a third one distinct from the previous two. However, its limits and constraints imply that PCR must not be considered as a routine assay. This emphasizes the need for more simple and rapid diagnostic tests, allowing the detection of HCV antigens and, as in hepatitis B, the progressive unravelling of the life cycle of HCV.