Association between the accumulation of hepatitis B virus core gene deletion mutants and progression of liver disease in long-term renal transplant patients

Hepatitis B virus and renal transplantation

Hepatitis B virus (HBV) infection remains an important cause of liver disease in the renal transplant (RT) population, potentially diminishing survival. Consequences of HBV infection after RT include progression to decompensated cirrhosis and an increased risk of hepatocellular carcinoma. Although precautions initially recommended by the Centers for Diseases Control and Prevention 30 years ago have substantially reduced HBV transmission within hemodialysis units, acute HBV outbreaks continue to be reported in patients with chronic kidney disease on maintenance hemodialysis. In addition, immigration from areas of high HBV prevalence implies that HBV-infected organs with chronic kidney disease will continue to enter the RT pool. Fortunately, the advent of oral therapy for HBV infection now reduces the risk of HBV progression post-RT.

Quantitative DNA fragment analysis for detecting low amounts of hepatitis B virus deletion mutants in highly viremic carriers

Many variants of hepatitis B virus (HBV) with deletions in the viral genome have been identified. Some of these variants are indicator or even effector of a more severe course of hepatitis. These deletion mutants contribute a variable and sometimes very low proportion to the viral population. For early detection of small amounts of deletion mutants among a large number of wild-type genomes, we applied a new screening method designated quantitative fragment analysis (QFA). By QFA the whole viral genome can be scanned for the presence of deletions or insertions of >/=3 nucleotides representing more than 2% of the viral population. Using QFA we showed that an often described deletion of 8 nucleotides is packaged in viral capsids and not a polymerase chain reaction (PCR) artifact. QFA was applied to study the emergence of deletion mutants in a group of 18 pediatric patients who had been infected from a common source while being under multidrug cancer chemotherapy. All patients had developed a highly viremic asymptomatic HBV carrier state. In 3 of these patients 3 different kinds of HBV deletion mutants were found by QFA: 8 bp deletions within the core promoter, core gene deletions from 8 to 86 bp, and large deletions of up to 1,989 bp spanning the precore/core and the preS/S reading frames. PCR primers that specifically amplify deletion variants enabled the detection of additional patients harboring the investigated variant.