Evolution of Reverse Transcriptase Region in Hepatitis B Virus during Sequential Nucleoside Analogues Therapy

• Main Authors: Sheng-Kai Jan, 詹勝凱
• Other Authors: Kung-Chia Young
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/68103266423863523264

碩士 === 國立成功大學 === 分子醫學研究所 === 97 === Chronic hepatitis B virus (HBV) infection is a worldwide health problem. Patients with chronic hepatitis B are at increased risk of developing cirrhosis, hepatic decompensation, and hepatocellular carcinoma (HCC). Several nucleoside analogues could be used as antiviral therapy, but the long-term therapy is necessary and the antiviral resistance develops one or several years later. Previous studies showed that long-term viral quasispecies evolutionary behavior is different between HBeAg seroconverters and nonseroconverters. At present, little is known about viral quasispecies evolution in the development of antiviral resistance after long-term treatment. This study is conducted to clarify the long-term viral evolutionary behavior in patients receiving sequential nucleoside analogues therapy. Chronic hepatitis B patients with lamivudine and entecavir resistance after receiving sequential lamivudine and entecavir therapy were enrolled as the study group, and then chronic hepatitis B patients receiving long-term entecavir therapy after development of lamivudine resistance were enrolled as the control group. Serum samples were collected for each patient at six time points: (I) before lamivudine treatment (II) six months after lamivudine treatment (III) occurrence of lamivudine resistance (IV) before entecavir treatment (V) six months after entecavir treatment (VI) occurrence of entecavir resistance. All of the samples were used for cloning and sequencing of the reverse transcriptase region. At least 20 colonies were selected and sequenced for each sample. All of the sequences are used for analysis of viral diversity, phylogenetic analysis and antiviral resistant mutation. The data showed that, after occurrence of lamivudine resistance, patients progressing entecavir resistance showed a striking increase in viral diversity. At the time point IV, patients progressing entecavir resistance had 2.5-fold higher viral diversity than at the time point III (P=0.031) and 2-fold higher viral diversity than patients responding to entecavir treatment at the same point (P=0.042). Viral diversity increased significantly may be associated with the coming of entecavir resistance and be used to predict the occurrence of entecavir resistance.