Vaccine 24 (2006) 4369–4377 Recombinant virus-like particles as a carrier of B- and T-cell epitopes of hepatitis C virus (HCV) Marija Mihailova a,b , Mechthild Boos a , Ivars Petrovskis b , Velta Ose b , Dace Skrastina b , Melanie Fiedler a , Irina Sominskaya b , Stefan Ross a , Paul Pumpens b , Michael Roggendorf a , Sergei Viazov a,∗ a Institute of Virology, Essen University Hospital, Essen 45122, Germany b Biomedical Research and Study Center, University of Latvia, Riga 1067, Latvia Received 13 December 2005; received in revised form 23 February 2006; accepted 28 February 2006 Available online 15 March 2006 Abstract The major aim of the project was the development of virus-like particles (VLP) displaying B- and T-cell epitopes of hepatitis C virus (HCV) proteins. To this end, hepatitis B virus core (HBc) particles were used as a carrier of HCV epitopes. Fragments of HCV genes encoding core (aa 98) and NS3 (aa 155) proteins were fused to the 3 ′ terminus of the truncated HBV core gene. All recombinant plasmids led to relatively high levels of expression of chimeric proteins in E. coli, which resulted in the formation of complete “mature” VLP. Chimeric HBc/HCV VLPs were purified by combination of gel filtration and sucrose gradient centrifugation, and used for immunogenicity studies in mice. All variants of hybrid particles induced high humoral and cellular responses to HBcAg. Immunization with the HBc/HCV core particles led to relatively low antibody and T-cell proliferative responses to HCV core epitopes. The HBc/HCV NS3 particles were able to induce high levels of anti-NS3 antibodies in the absence of proliferative responses to HCV epitopes. Thus, the results of the current study have demonstrated the principal possibility of using VLP on the basis of HBcAg for creation of a new type of HCV-specific immunogen. © 2006 Elsevier Ltd. All rights reserved. Keywords: Hepatitis C virus; Vaccine; Virus-like particles 1. Introduction Hepatitis C virus (HCV) infection has become the most common cause of chronic liver disease in Europe and else- where. According to the World Health Organisation [http:// www.who.int/mediacentre/factsheets/fs164/en/index.html] about 170 million people worldwide are infected with HCV, of whom probably more than 50% will develop chronic hepatitis, leading to cirrhosis in 10–20%, and hepatocellular carcinoma in 1–5% of infected individuals. Such life-threatening sequelae make hepatitis C also the major cause of liver transplantation in developed countries. Currently, the only therapy for chronic HCV infection that has a lasting beneficial effect is systemic treatment with ∗ Corresponding author. Tel.: +49 201 7233533; fax: +49 201 7235929. E-mail address: sergei.viazov@uni-essen.de (S. Viazov). pegylated interferon alpha (IFN-) in combination with ribavirin, but a sustained response is achieved usually in only 50–80% of patients depending on a viral genotype. Thus, it is not likely that the number of HCV infected individuals, who are also the source for new infections, will be significantly reduced in the near future. The situation clearly emphasize the need for novel prophylactic/therapeutic approaches that would prevent spread of HCV and would provide more efficient antiviral therapy of individuals suffering from a chronic hepatitis C. It is assumed that induction of vigorous, long-lasting, and cross-reactive antiviral antibodies as well as a multispecific cellular immune response that includes both helper and cyto- toxic T lymphocytes are necessary for an effective HCV vac- cine [1–5]. The development of such a vaccine meets, how- ever, with many difficulties. The natural course of HCV infec- tion and mechanisms of HCV interaction with an infected 0264-410X/$ – see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.vaccine.2006.02.051