| Hepatitis B infection remains a major health problem in many regions including Asia, Africa, the Middle East and the Pacific Islands. An estimated 350 million people worldwide carry the hepatitis B virus (HBV) and about 5 % of those who become infected will die as a consequence of cirrhosis (severe liver scarring) and liver cancer. In china, the carrier rates for chronic hepatitis B infection range about from 10 to 20%. Chronic hepatitis B virus (HBV) infection has already become a common cause of decompensated end-stage liver disease. A liver transplant (LT) operation is often the only option left open to doctors treating patients with life-threatening liver damage induced by hepatitis B. Hepatitis B virus-infected patients form a large indication for orthotopic liver transplantation (OLT). However,the recurrence of hepatitis B virus (HBV) infection in patients transplanted for chronic hepatitis B is almost universal and is associated with poor survival rates . Prophylaxis of recurrent hepatitis B using either immune or antiviral therapies has some limitations. For example, long-term HBIg and/or lamivudine(LMV) administration reduces the rate of HBV recurrence but it should result in the selection of HBV mutants, and the emergence of those viral variants results from one or more mutations in HBV HBsAg genome or the tyrosine-methionine-aspartate-aspartate (YMDD) locus of the HBV polymerase gene respectively. Polymerase gene is the nucleotide-binding domain for virally encoded DNA polymerase. In addition, the genome of HBV is organised in to overlapping reading frames. The S gene is completely overlapped by the polymerase gene. As a consequence, mutations in the overlapping polymerase gene may produce changes in the S gene.Quasispecies are a conception that is used to describe the genetic heterogeneity of same organism, it was first advanced by Eigen. In the research field of virology, quasispecies are used to describe the heterogeneity of same virus in an infected individuality. HBV is an enveloped, partly double-stranded DNA virus containing a genome of approximately 3200 base pairs. The potential for hepatitis B virus (HBV) to alter its genome is considerable. This occurs because the virus utilizes a reverse transcription step in replicating the viral genome. Like human immunodeficiency virus, the reverse transcriptase of HBV is error prone and as a consequence of specific selection pressures within a host a population of viral quasispecies emerges. HBV quasispecies have been detected in patients with chronic hepatitis B. HBV mutants with survival advantages over the wild type virus appear within the selective in vivo environment. To date, there are no reports, on the correlation between the course of HBV quasispecies forming in the polymerse gene and graft liver HBV infection. In this paper, to preliminary investigate the rates of HBV reinfection after OLT with LMV prophylaxis and the antiviral effect of adefovir (ADV) to LMV-resistant populations of HBV reinfection. Meanwhile, to study whether HBV polymerase gene has quasispecies characteristic and the quasispecies heterogeneity in the patients with HBV reinfection after OLT. Sequential serum samples or liver tissue was obtained from 7 consecutive patients with HBV reinfection after LT, and the B to D domain(460bp) in reverse transcriptase (RT) region of HBV was amplified by PCR or nested-PCR and cloned. The experimental procedure, PCR-T vector clone-nucleotide sequence analysis, was first employed. HBV polymerase gene quasispecies were assessed by a method that combined a single-stranded conformational polymorphism (SSCP) method and heteroduplex analysis (HD). Random selected 34 clones from these cloning samples were examined by SSCP/HD. Finally, to satisfy the need of detection a lot of virogene sequences in the study of HBV quasispecies, the sequence analysis was finished by DNA Instrument. In addition, the stdudy also amplified and cloned the A to E domain(788bp) of HBV RT gene from 2 ADV-inefficacy patients of HBV reinfection, then sequence ana...
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