Construction of a duck hepatitis B virus YMDD mutant and identification of its resistance phenotype / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct a lamivudine-resistant plasmid containing 1.2 unit genome of duck hepatitis B virus and identify its replication and drug-resistance in avian LMH hepatica cells.</p><p><b>METHODS</b>The recombinant plasmid PBS-DHBV1.2 was constructed using the 1.2-genome length DHBV DNA sequence from a dimer DHBV genome with pcDNA3.1 as the template. With site-directed mutagenesis, we obtained PBS-DHBV1.2-M512V plasmids with polymerase gene mutation from PBS-DHBV1.2. Two constructed plasmids were transiently transfected into LMH cells using FuGENETM6 transfection reagent and cultured in the medium containing different concentrations of lamivudine. Southern blot hybridization was performed to detect DHBV replication intermediates.</p><p><b>RESULTS</b>PCR amplification, restriction digestion and plasmid sequencing all confirmed successful construction of PBS-DHBV1.2-M512V recombinant plasmid. Southern blot analysis identified the presence of all the expected DHBV replication intermediates in LMH cells. The replication capacity of the mutant plasmid was decreased by 2.7 times compared with that of the wild plasmid. The IC(50) of lamivudine was 37.12∓8.81 ng/ml for the mutant, greater than that of the wild plasmid (10.90∓4.80 ng/ml).</p><p><b>CONCLUSION</b>Compared with the wild plasmid, the mutant plasmid has a lower replication capacity and sensitivity to lamivudine in vitro.</p>

Stable expression of HBV C gene mutants in immortalized human B-cell lines / 南方医科大学学报

<p><b>OBJECTIVE</b>To provide an cell model of immortalized lymphoblstoid B-cell lines for studying the biological characteristics of full-length hepatitis B virus (HBV) genome carrying the hot-spot mutations V60, G87, and L97.</p><p><b>METHODS</b>V60, G87, and L97 mutation points were introduced into HBV p3.8 II plasmid containing 1.2 copy of HBV genome by means of site-directed mutagenesis. The HBV genome was amplified by PCR from p3.8 II and p3.8 II-V60, G87, L97 plasmid, and the PCR product was inserted into EBO-plpp eukaryotic expression vector. The recombinant vectors and the EBO-plpp vector were transfected into immortalized human lymphoblasts with lipofectamine 2000 and selected with hygromycin. Steady expression of the target genes was determined by RT-PCR, Western blotting and microparticle enzyme immunoassay.</p><p><b>RESULTS</b>DNA sequence analysis indicated that the desired mutation was introduced into wild-type HBV DNA. HBsAg, HBeAg and HBcAg could be detected in EBO-HBV-transfected cell lysate or culture supernatant.</p><p><b>CONCLUSION</b>Transfectants that stably express HBV mutant antigen may provide a cell model to study the biological characteristics of HBV carrying hot-spot mutation in vitro.</p>