Expression of hepatitis B virus surface antigen in adult rat liver. Co-introduction of DNA and nuclear protein by a simplified liposome method

Abstract

We established a simple and efficient method for gene transfer in vitro (to cultured cells) and in vivo (to an adult organ) using liposomes.Plasmid DNA and proteins were efficiently co-encapsulated in liposomes by agitation and sonication, and were co-introduced into cells by hemagglutinating virus of Japan (HVJ)-mediated membrane fusion.Introduction of the Escherichia coli &galactosidase gene with non-histone chromosomal protein high mobility group 1 (HMG1) into LLCMKz cells resulted in about 3 times higher 8-galactosidase activity than that on introduction of the gene alone.Two days after injection of HVJ-liposomes containing the &galactosidase gene and HMGl under the perisplanchnic membrane of adult rat liver, hepatic cells near the injection site were found by 5-bromo-4chloro-3-indolyl fl-D-galactoside staining to have Bgalactosidase activity.After similar injection of HVJliposomes containing the hepatitis B virus surface antigen (HBsAg) gene and HMG1, HBsAg was detected in the serum for 9 days with a maximum of 25-45 ngl ml on day 2 after the injection.Methods for introducing exogenous genes into various types of cells in vitro and in uiuo have been developed to study the biological functions of macromolecules, to establish animal models of human diseases, and for postnatal gene therapy.Many methods for introducing macromolecules into cultured cells (in vitro) have been reported (1, 2).Methods for gene transfer by liposomes and HVJ' have been developed in our laboratory (3, 4).Frequency of gene transfer by the liposome method into adhesive cultured cells is comparable to that by calcium phosphate precipitation, and this method