Diagnosis of hepatitis B virus (HBV) infection is primarily based on HBV serologic markers such as hepatitis B surface antigen (HBsAg) and hepatitis B core IgM antibody (anti-HBc IgM). Measurement of HBV DNA in serum helps to diagnose early acute infections before HBsAg becomes detectable, distinguish active from inactive HBV infection and monitor response to therapy.
The presence of HBV DNA in serum is a reliable marker of active HBV replication. HBV DNA is detectable within 30 days after infection and approximately 21 days before HBsAg becomes detectable. Testing for serum HBV DNA may be useful in diagnosing acute HBV hepatitis in patients with equivocal HBsAg test results.
Patients who do not clear the virus develop chronic HBV infection and remain HBsAg positive. Chronic hepatitis can be classified as chronic active or chronic inactive hepatitis, based on the presence or absence, respectively, of hepatitis Be antigen and HBV DNA. Some patients with chronic inactive hepatitis may reactivate HBV replication, without expressing HBeAg. Detection of HBV DNA is the only way to detect reactivation of HBV replication.
Patients with hepatitis B are treated with nucleoside or nucleotide analogs such as lamivudine, adefovir, entecavir and tenofovir. The therapeutic goal of treatment for chronic active hepatitis is to achieve long-term suppression of viral replication as indicated by loss of HBeAg and undetectable HBV DNA. These patients must also be monitored for the emergence of drug-resistant HBV strains, which is indicated by the reappearance of HBV DNA after it had become undetectable or by an increase in HBV DNA levels following an initial decline.
COBAS AmpliPrep/COBAS TaqMan HBV Test, v2.0 is an FDA-approved in vitro nucleic acid amplification test for the quantification of hepatitis B virus (HBV) DNA in human serum. This assay targets the highly conserved pre-Core/Core region of the HBV genome. This assay detects all hepatitis B virus (HBV) genotypes from A to H The quantification range of this assay is 20 to 170,000,000 IU/mL, which is equivalent to 1.30-8.23 log IU/mL. The lower limit of quantification (LLoQ) is 20 IU/mL. Very low levels of HBV DNA below the LLoQ may be detected but cannot be quantitated.
Reference value is undetected
Specimen requirement is a red top tube of blood. Serial testing at 1 to 2 month intervals is recommended for assessing disease progression or monitoring response to anti-HBV therapy.
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2. Chevaliez S, Bouvier-Alias M, Laperche S, et al: Performance of version 2.0 of the Cobas AmpliPrep/Cobas TaqMan Real-Time PCR Assay for hepatitis B virus DNA quantification. J Clin Microbiol 2010;48:3641-3647