Downloaded from www.microbiologyresearch.org by IP: 54.144.26.64 On: Fri, 29 Jan 2016 06:09:21 A chimeric GB virus B encoding the hepatitis C virus hypervariable region 1 is infectious in vivo G. Haqshenas, 1 3 X. Dong, 1,2 3 H. Netter, 2 J. Torresi 3 and E. J. Gowans 1,2 Correspondence G. Haqshenas haqshenas@burnet.edu.au 1 The Macfarlane Burnet Institute, GPO Box 2284, Melbourne, VIC 3001, Australia 2 Department of Microbiology, Monash University, Clayton, VIC 3800, Australia 3 Department of Medicine (RMH/WH), University of Melbourne, Centre for Clinical Research Excellence, Royal Melbourne Hospital, Parkville, VIC, Australia Received 12 August 2006 Accepted 15 November 2006 Two GB virus B (GBV-B) chimeric genomes, GBV-HVR and GBV-HVRh (with a hinge), containing the coding region of the immunodominant hypervariable region 1 (HVR1) of the E2 envelope protein of Hepatitis C virus (HCV) were constructed. Immunoblot analysis confirmed that HVR1 was anchored to the GBV-B E2 protein. To investigate the replication competence and in vivo stability of in vitro-generated chimeric RNA transcripts, two naı ¨ve marmosets were inoculated intrahepatically with the transcripts. The GBV-HVR chimeric genome was detectable for 2 weeks post-inoculation (p.i.), whereas GBV-HVRh reverted to wild type 1 week p.i. Sequencing analysis of the HVR1 and flanking regions from GBV-HVR RNA isolated from marmoset serum demonstrated that the HVR1 insert remained unaltered in the GBV-HVR chimera for 2 weeks. Inoculation of a naı ¨ve marmoset with serum collected at 1 week p.i. also resulted in viraemia and confirmed that the serum contained infectious particles. All animals cleared the infection by 3 weeks p.i. and remained negative for the remaining weeks. The chimera may prove useful for the in vivo examination of any HCV HVR1-based vaccine candidates. INTRODUCTION Hepatitis C virus (HCV) causes acute and chronic hepatitis, which can lead to liver cirrhosis and hepatocellular carcinoma (Alfonso et al., 2004; Alter & Seeff, 2000; Poynard et al., 2003). The infection is resolved in a proportion of acute cases, but persists for life in >80 % of infected patients. Although the current treatment regimen can cure 40–80 % of infected individuals, the number of HCV carriers continues to increase. There is no effective vaccine and HCV infection is considered to be one of the major health problems worldwide (McHutchison, 2004). HCV is classified within the family Flaviviridae, the members of which are small, icosahedral, enveloped viruses that contain a positive-sense RNA genome (Bartenschlager & Lohmann, 2000; Lindenbach & Rice, 2001). The family Flaviviridae consists of three genera: Flavivirus, Pestivirus and Hepacivirus. It was suggested that three novel proposed members of the Flaviviridae, the GB agents [GB virus (GBV) A, B and C], should be classified in a separate genus within the Flaviviridae or in a subgenus of Hepacivirus (Muerhoff et al., 1995). The HCV genome encodes two envelope glycoproteins, E1 and E2, that contain the essential signals for cell attachment and internalization (Bartosch et al., 2003; Zhou et al., 2000). The first 27–31 N-terminal amino acids of the HCV E2 protein have a high degree of sequence variability among different HCV isolates and, consequently, this region is termed hypervariable region 1 (HVR1) (Alfonso et al., 2004; Hijikata et al., 1991; Kurosaki et al., 1994; Weiner et al., 1991). This highly immunogenic domain has been suggested to contain a dominant neutralizing epitope (Farci et al., 1996). Several in vitro studies showed that binding of HCV particles to permissive cells was inhibited by either polyclonal (Shimizu et al., 1996; Zhou et al., 2000) or monoclonal (Zibert et al., 1995) antibody against HVR1. Moreover, two independent in vivo studies also showed that homologous anti-HVR1 antibodies were able to neutralize the virus (Esumi et al., 2002; Farci et al., 1996). The high cost of chimpanzees, the only animal that can support HCV replication, has encouraged the development of novel models for HCV study. GBV-B is a close relative of HCV that causes hepatitis in tamarins and marmosets, and represents an attractive model for HCV (Bright et al., 2004; Bukh et al., 2001; Jacob et al., 2004; Lanford et al., 2003; Martin et al., 2003). The virus was characterized fully in 1995 (Muerhoff et al., 1995; Simons et al., 1995) and infectious clones were constructed a few years later (Bukh et al., 1999; Sbardellati et al., 2001). 3These authors contributed equally to this work. A supplementary table showing oligonucleotide primers designed and used in this study is available in JGV Online. 0008-2467 G 2007 SGM Printed in Great Britain 895 Journal of General Virology (2007), 88, 895–902 DOI 10.1099/vir.0.82467-0