Comparison of drug resistance mutations associated with hepatitis B virus covalently closed circular DNA and relaxed circular DNA / 中华传染病杂志

ABSTRACT

Objective To detect nucleos(t)ide-resistance mutations in hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) isolated from hepatocytes of patients with chronic HBV infection and to analyze the correlation between the mutations found in cccDNA and relaxed circular DNA (rcDNA). MethodsForty patients with chronic HBV infection were investigated. Preoperation serum samples and non-tumor liver tissues were collected.Intrahepatic HBV cccDNA and rcDNA were selectively extracted by co-precipitation of sodium dodecyl sulphate-protein and QIAamp DNA Mini Kit, and further purification with plasmid-safe ATP-dependent DNase (PSAD).Thereafter,cccDNA were amplified by selective polymerase chain reaction (PCR) or nested PCR using the primers spanning both the two gaps in HBV genome and covering the common mutations associated with nucleoside analogues resistance (rt169- rt250).Intrahepatic HBV rcDNA and pre-operation serum HBV rcDNA were also extracted and then amplified by PCR.The PCR products were then purified and sequenced.Results Among the 40 patients,intrahepatic HBV cccDNA were detected in 31 patients,and HBV rcDNA were detected in liver samples of 35 patients and pre-operation serum samples of 21 patients. The PCR products amplified from these samples were all successfully sequenced.rtM204Ⅰ mutation was detected in intracellular HBV cccDNA,rcDNA and serum HBV rcDNA in 2 patients.Both rtM204Ⅰ and rtQ215H were detected in intrahepatic HBV cccDNA and rcDNA in 2 patients,while no corresponding mutation was observed in serum HBV rcDNA of these two patients.Three variants including rtM204V,rtM204V and rtV173L-rtL180M-rtM204V were detected in serum HBV rcDNA in 3 patients,while corresponding mutants were not detected in intracellular HBV cccDNA or rcDNA of these patients.Condsions The results suggest that antiviral nucleos(t) ide resistance mutations can be found in HBV cccDNA in chronic hepatitis B patients. The dominant resistant mutation found in intrahepatic HBV cccDNA/rcDNA may be different from that in serum HBV rcDNA.