to other flaviviruses. [12][13][14][15] Recently it was demonstrated that Transgenic mice have been produced that express the HCV core can form homodimers and probably multimers 16 hepatitis C virus (HCV) core protein in the liver under similar to the nucleocapsid proteins of retroviruses 17,18 and the transcriptional control of the mouse major urinary HBV. 19,20 In vitro expression of HCV core in different cell protein promoter. These animals express the full length lines has generated conflicting data in terms of protein size, core protein in cytoplasm of their hepatocytes at levels posttranslational modification, and subcellular localizacomparable to those detected in naturally infected pation. 12,15,21,22 [25][26][27][28][29] They are both believed to be that it inhibits HBV replication in HuH-7 cells after trantransmembrane glycoproteins, with C-terminal hydrophobic sient transfection in vitro. We have also produced anchors. After synthesis and glycosylation, E1 and E2 fold transgenic mice in which a C-terminally truncated and associate primarily through noncovalent interactions (aa384-715) glycosylated HCV E2 protein is expressed in with a slow kinetics as shown in vitro by pulse-chase experithe liver under the transcriptional control of the mouse ments. 30 The HCV glycoproteins are predominantly localized albumin promoter. Despite the high level expression of in the endoplasmic reticulum (ER) and are not translocated HCV E2 protein, no evidence of liver disease was debeyond the cis Golgi. 28,30 Purified E1E2 oligomers have been tected in these animals. These results suggest that the used to successfully immunize chimpanzees against chal-HCV core and E2 proteins are not cytopathic for the lenge with low doses of homologous HCV-1, 31 but it is not hepatocyte in vivo, and they represent an initial step in known if the protection is mediated by neutralizing antibodthe development of a small animal model of HCV immuies or other immune mechanisms. nopathology. (HEPATOLOGY 1997;25:719-727.)In the absence of an efficient cell culture system and convenient animal models to study HCV pathogenesis, we have Hepatitis C virus (HCV) is a parenterally transmitted hep-produced transgenic mice in which HCV core and HCV E2 atotropic virus that, like hepatitis B virus (HBV), causes are expressed in the liver under the control of the developacute and chronic hepatitis and hepatocellular carcinoma. [1][2][3][4] mentally regulated, liver-specific mouse major urinary pro-HCV is a positive stranded RNA virus whose genome (about tein (MUP) and constitutively active mouse albumin (ALB) 9.6 kb) contains a single uninterrupted open reading frame promoters. The characteristics of these animals form the ba-(ORF) that encodes a polyprotein of 3010-3011 amino sis for the current report. acids. 1,[5][6][7][8] In vitro studies have demonstrated that the polyprotein is processed by cellular and viral proteases to produce MATERIALS AND METHODSat least ten different viral structural and nonstructural proteins, whose order is C-E1-E2-E2/p7...

In this study, we examined the ability of the hepatitis B virus (HBV) precore, envelope, and X gene products to modulate HBV replication in the livers of transgenic mice that replicate the virus. Hepatic HBV replication was not affected by overexpression of the envelope or X gene products when these animals were crossed with transgenic mice that express the corresponding viral genes in the hepatocyte. Overexpression of the precore protein, however, eliminated nucleocapsid particles from the cytoplasm of the hepatocytes and abolished HBV replication without affecting the hepatic steady-state content of pregenomic HBV RNA. These observations suggest that the precore protein can exert a dominant negative effect on HBV replication, presumably at the level of nucleocapsid particle maturation or stability, suggesting an important role for this enigmatic viral protein in the HBV life cycle.