Hepatitis B virus DNA Drug Resistance Test

Why Get Tested?
To determine a patient’s hepatitis B virus genotype (A-H) and to detect a viral mutation that may be associated with resistance to current treatments.

Description:
Hepatitis B virus (HBV) is an enveloped, partially double stranded DNA virus which infects the liver of humans characterized by inflammation & sometimes enlargement of the liver. It has various causes, one of which is infection by a virus. HBV is one of five "hepatitis viruses" identified so far that are known to mainly infect the liver. The other four are hepatitis A, hepatitis C, hepatitis D, and hepatitis E. The virus multiplies in the liver cells and in the process destroys the cells.

Without proper diagnosis and treatment on time, chronic HBV infection can lead to fatal liver disease like cancer and it is known to be the 10^th leading cause of death in the world. Approximately 600,000 deaths occur every year as a result of the acute and chronic consequences of HBV infection. Disease chronicity rates are ?5% in generally healthy infected adults and 80–90% in perinatally infected children. Chronic HBV affects nearly 350 million patients worldwide and may further progress to cirrhosis and/or hepatocellular carcinoma (HCC) in 15–40% of cases.

HBV genotyping is important in determining the clinical manifestation of disease and treatment response, particularly, in patients with low viral loads. The Virus shows high genetic diversity with 8 genotypes (A-H) and several subtypes. Also, sensitive detection of HBV antiviral drug resistance mutations is essential for monitoring anti-virul response. Genotyping and Resistance Mutation Detection: The RT region of the HBV genome is amplified by end point PCR and loaded on to 1% agarose gel.The PCR product is then purified and subjected to automated sequencing by sanger’s method. The resultant sequence data is then analyzed both manually and by software. The analyzed data is then compared with the database to detect genotype and mutations.

Reasons for Referral:
When patient have risk factors for HBV infection primarily “a positive HBsAg test result means that patient are infected and can spread the hepatitis B virus or when patient have signs and symptoms of hepatitis, such as jaundice or unexplained elevated blood levels or when patient are being treated for HBV or hepatitis C (HCV).

Sample Requirement:
Plasma

Test Preparation
No test preparation is needed.

Test Done by
RT–PCR & 3500Dx Genetic Analyzer (CE, IVD, Applied Biosystems, USA)