Assay Sheet
Test ID
1100 Hepatitis B (HBV) Real-time qPCR
CPT Code
87517
Clinical Utility
Hepatitis B quantitative DNA PCR can be used in conjunction with clinical presentation and other laboratory markers of disease status as an aid in managing individuals infected with HBV. Results from the assay can potentially be used to assess disease progression and to monitor the efficacy of antiviral therapy by measuring changes in HBV DNA levels during the course of therapy. Viral load tests should not be used to diagnose HBV infection.
Procedure
Extraction of DNA from plasma; amplification and detection of hepatitis B genotypes A through G using real-time, quantitative PCR. An internal control is added to ensure the extraction was performed correctly and the PCR reaction was not inhibited.
Specimens
Whole Blood: 7-10 ml submitted in EDTA, ACD Solution A, or PPT sterile tube.
Minimum specimen requirement is 2 ml plasma.
- Separate plasma from cells within 4 hours of collection by centrifuge at 1000 xg for 10-15 minutes. Do not clarify by filtration or further centrifugation.
- Ship ambient or frozen.
Specificity
Detects all 7 HBV genotypes. The primers and probes used in this assay are specific for HBV.
Hepatitis B Virus Assay Range
5 to 200,000,000 IU/ml plasma
Reported in 4 formats:
- IU/ml
- copies/ml
- Log IU/ml
- Log copies/ml
Turnaround Time
Within 24 hours of receiving specimen
DOWNLOAD ASSAY SHEET
PCR tests are performed pursuant to a license agreement with Roche Molecular Systems, Inc.
This assay was developed and the performance characteristics were determined at ViraCor Laboratories. This test is performed in a CLIA certified laboratory. FDA approval is not required for the performance of this test.
AS14-0108
Pathogen Overview
ABOUT THE HEPATITIS B VIRUS
Hepatitis B virus (HBV) is a small, hepatotropic DNA virus. It is the prototype member of a family of closely related viruses called Hepadnaviradae. HBV is the only member of the Hepadnaviradae family that infects humans. The HBV genome is composed of a relaxed, circular, partially double-stranded DNA molecule. There are 6 HBV genotypes: A – F.
HEPATITIS B VIRUS CLINICAL MANIFESTATIONS
HBV infection may be symptomatic or asymptomatic, though more likely to be symptomatic in young children. More than 95% of HBV infections in adults are self-limiting, the virus is cleared about 6 months post-infection and the patient is immune to reinfection. Symptoms of acute infection can include jaundice, fatigue, abdominal pain, loss of appetite, nausea, vomiting and joint pain.
Hepatitis B is transmitted by direct contact with the blood or body fluids of an infected person; for example having sex or sharing needles with an infected person. Infants can be infected as they pass through the birth canal of an infected mother, where they are exposed to large amounts of the virus. Hepatitis B is not spread through food, water or by casual contact. However, the virus can be spread by sharing personal items that might have small amounts of blood present, such as toothbrushes or razors. High risk populations include people who practice unsafe sex, drug abusers and hospital workers who have exposure to blood products.
HBV Vaccine: In 1982, a hepatitis B vaccine was made available. The number of new infections per year has declined from an average of about 260,000 in the 1980s to about 78,000 in 2001. This great decline has occurred in children and adolescents as a result of the vaccine. The HBV vaccine is now routine in the immunization schedule of infants and children.
Chronic HBV Infections: About 5% of adults will not resolve the infection and go on to become a chronic carrier. Conversely, chronic infections occur in 90% of infants infected at birth, 30% if infected at age 1-5 years and 6% if infected after age 5. Chronic infection is more common in infants due to their poorly developed cellular immune response. There are an estimated 1.25 million chronically infected Americans of whom 20-30% acquired their infection in childhood.
The clinical course of individuals that are chronically infected is highly variable, ranging from asymptomatic to a small subset with severe chronic active hepatitis, who have a 5 year survival rate of less than 50%. The reasons that some develop a chronic infection remain poorly understood. Evidence suggests that variation in host immune response is a critical factor. Individuals with overt deficits in cell-mediated immunity, such as transplant patients and HIV patients, are more likely to become chronic carriers than those with a fully competent immune response.
About 30% of chronic carriers will have no signs or symptoms. The asymptomatic carriers are the primary reservoir of infection; it is from these individuals that the spread of HBV to susceptible hosts occurs. Adults are more likely than children to be symptomatic. Symptoms can include jaundice, fatigue, abdominal pain, loss of appetite, nausea, vomiting and joint pain. Some patients will remain in generally good health but have persistent or recurrent elevations in liver enzymes (AST/ALT) without jaundice. Persistent mild hepatomegaly is not unusual and splenomegaly is occasionally present. Unfortunately, a significant number of chronically infected individuals will develop cirrhosis, hepatic failure or hepatocellular carcinoma.
Just a decade ago, HBV infection was considered a contraindication to liver transplant because of frequent viral recurrences and the development of associated liver disease, which led to graft failure and death. Antiviral therapies have diminished the risk of HBV recurrence and led to improvements in patient and graft survival. HBV infection after a liver transplant can be classified into two groups; patients who have HBV recurrence who were transplanted because of HBV end-stage liver disease and patients who develop HBV after the transplant from their donors or from a community acquired infection.
HEPATITIS B VIRUS LABORATORY DIAGNOSIS
HBV infection can be diagnosed and monitored with a number of antibody and antigen assays. There are a wide variety of laboratory assays available to differentiate acute from chronic infection, to assess the immune status of an individual or to evaluate infectivity and prognosis. There are a number of excellent reviews in the primary literature to assist in understanding the immune response to HBV.
Due to the highly sensitive and specific nature of quantitative real-time PCR, it has become the standard of care for assessment of viral burden (viral load) in a patient undergoing treatment for HBV. HBV often achieves titers of greater than 10e9 IU/ml; for this reason it is important that the quantitative real-time PCR assay employed to follow the patient have an extremely wide assay range. The ViraCor HBV assay has a range of 5 to 200,000,000 IU/ml.
HEPATITIS B VIRUS TREATMENT
Treatment of Hepatitis B has evolved from isolation and bed rest in the 1950s to development of antiviral therapies in the 1990s. The ideal goal of treatment is to eradicate HBV, but this may not be achievable. The indications for treatment include evidence of viral replication and abnormal ALT levels. Patient age, severity of liver disease, likelihood of response and the potential for adverse events must be weighed before treatment is initiated. There are a variety of treatment options available for HBV chronic infections, with the understanding of treatment rapidly evolving at this time. For an excellent review of treatment options, the Hepatitis B Foundation website is recommended: http://www.hepb.org/treatment/aasld_guidelines.htm .
Selected References
Centers for Disease Control and Prevention. http://www.cdc.gov
Hepatitis B Foundation. http://www.hepb.org
Knipe D, Howley P. Fields Virology. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006.
PAO-05-0707 PCR tests are performed pursuant to a license agreement with Roche Molecular Systems, Inc.
DOWNLOAD PATHOGEN OVERVIEW
ViraCor’s Hepatitis B quantitative DNA PCR assay is used in conjunction with clinical presentation and other laboratory markers of disease status as an aid in managing individuals infected with HBV. Results from the assay can potentially be used to assess disease progression and to monitor the efficacy of antiviral therapy by measuring changes in HBV DNA levels during the course of therapy. Viral load tests should not be used to diagnose HBV infection.