Realtime PCR techniques generally display a broad, dynamic range of quantification, well suited to clinical needs. Realtime PCR is more sensitive than classical PCR, it does not yield false-positive results due to carry-over contaminations and it can be fully automated.¹ Realtime PCR has become the technique of choice for detecting and quantifying viral genomes in clinical practice. Several realtime PCR kits are commercially available for the detection and quantification of both HBV DNA and HCV RNA (see Table 1).

Utility of Realtime Polymerase Chain Reaction in the Management of Chronic Hepatitis B

Diagnosis and Prognosis
HBV DNA detection is not needed to diagnose acute hepatitis B.² In contrast, HBV DNA quantification has valuable clinical utility in chronic hepatitis B surface antigen (HBsAg) carriers. Indeed, chronic hepatitis B is defined by permanent or transient serum-aminotransferase level elevation with hepatic lesions on liver biopsy (inflammation and/or fibrosis) in patients with an HBV DNA level of more than 103–105 IU/ml, according to hepatitis B e antigen (HBeAg) status. The diagnosis of chronic hepatitis B is easier to make with realtime PCR methods than with previously available techniques. This is a result of the improved analytical sensitivity and broader dynamic range of quantification with realtime PCR, which spans the clinically meaningful thresholds. With highly sensitive realtime PCR assays, however, there is a risk of detecting low-level HBV DNA in virtually all chronic HBsAg carriers. Thus, it is important that clinically relevant thresholds be carefully identified and that HBV DNA levels be interpreted in the light of the clinical, biological and histological context, especially at the time of treatment decisions.

The presence of HBV DNA in serum is associated with a risk of developing cirrhosis and hepatocellular carcinoma (HCC).³ The risk of developing HCC is minimal in the absence of detectable HBV DNA, except in cirrhotic patients. In patients with detectable HBV replication, the risk of HCC correlates with the level of viral replication.⁴ Realtime PCR techniques have a substantial prognostic value as a result of their ability to quantify HBV DNA over a broader dynamic range of levels than classical PCR techniques, with similar performance for all HBV genotypes (Chevaliez et al., manuscript submitted).