Development of a hepatitis C virus vaccine using papillomavirus-like particles for antigen delivery

Loyola University Chicago, Maywood IL

Investigators

Abstract

Abstract Over 200 million people worldwide are infected with HCV. The majority of these people will progress to chronic infection, resulting in severe liver disease such as cirrhosis and hepatocellular carcinoma. Thus, an effective HCV vaccine would be ideal to prevent HCV infection and liver disease worldwide. Papillomavirus-like particles are the major components of the licensed human papillomavirus vaccines from GSK and Merck. The virus-like particles (VLPs) formed by papillomavirus L1 protein are highly immunogenic even in the absence of adjuvants. The surface loops of the L1 protein can be replaced to express foreign sequences and immunization with the VLPs formed by the chimeric proteins can induce strong antibody responses against the inserted epitopes. Furthermore, the VLPs are able to package DNA plasmids expressing genes of interest to form pseudoviruses (VLPs with plasmid inside). The pseudoviruses are able to elicit strong antibody and T-cell responses via systemic immunization. We hypothesize that papillomavirus pseudoviruses can be used to present linear HCV envelope epitopes to the immune system on the surface loops of L1 to induce high titers of neutralizing antibodies while at the same time deliver plasmids encapsulated within the pseudovirus particles to induce strong HCV specific T-cells to the HCV NS3 protein. We plan to insert known HCV neutralizing antibody epitopes (polyprotein amino acids 412 ? 426 and 496 ? 515) into the bovine papillomavirus L1 protein three surface loops. We will make BPV-HCV chimeric VLPs (CVLPs) with the chimeric L1 and L2 proteins using a baculovirus expression system. We plan to immunize mice with the CVLPs and determine neutralizing antibody titers against HCV cell culture virus. The goal is to make a CVLP presenting the two HCV neutralizing epitopes. Furthermore, we will insert the HCV NS3/NS4A native sequence as well as a rearranged NS3 sequence into a plasmid for expression under a mammalian promoter. The rearranged sequence is to increase the instability of NS3 which will in turn increase degradation and result in increased T-cell responses. We will use the developed CVLP to package the plasmids to form BPV-HCV pseudoviruses. We will immunize mice with the pseudoviruses carrying the NS3/4A plasmids intramuscularly as well as Adenovirus expressing NS3/4A (a positive control) and test splenic T-cells by ELISPOT and flow cytometry to assess polyfunctionality and phenotypes induced by the pseudoviruses. Finally we will use the pseudovirus that induces strong neutralizing antibody and CTL responses to immunize a humanized HCV infection mouse model (Dorner-Ploss) which is susceptible to HCV infection, and challenge them with HCV to assess protective qualities of the induced immune responses.