Replication and encapsidation of HBV mutants with the truncated C gene

Objective To evaluate the replication and encapsidation of HBV mutants with the truncated C gene. Methods The HBV mutants with the truncated C gene were constructed by molecular cloning and PCR-based deletion in vitro . The replication and encapsidation of HBV mutants were investigated by Southern blotting,PCR and real-time fluorescence PCR respectively after transfecting the HBV mutants plasmid into HepG2 cells by using liposome. Results The C-truncated HBV mutant vectors were constructed successfully and confirmed exactly by clone sequencing and enzymes digestion. The C-truncated HBV mutants were replication-defective, however,all types of HBV DNA could be detected positive in the cytoplasm and supernatant after co-transfecting the C-truncated HBV mutants plasmid and the helper constructs into HepG2 cells. The C-truncated HBV mutants were proved to produce 3-40 folds more progeny DNA than that of the wild-type HBV by DNA quantitative assay. Conlusion The C-truncated HBV mutants are replication-deficient and could not replicate and encapsulate in the hepatocytes when transfected solely,however,the progeny HBV-variant viruses are encapsidated more effectively to secrete into supernatant when co-tranfected with the helper construct which lacks part of 5′-proximal HBV RNA packaging signal e.