Evaluating Replication-Defective Vesicular Stomatitis Virus as a Vaccine Vehicle

Abstract

We have generated replication-competent (VSV-C/E1/E2) and nonpropagating (VSV⌬G-C/E1/E2) vesicular stomatitis virus (VSV) contiguously expressing the structural proteins of hepatitis C virus (HCV; core [C] and glycoproteins E1 and E2) and report on their immunogenicity in murine models. VSV-C/E1/E2 and VSV⌬G-C/E1/E2 expressed high levels of HCV C, E1, and E2, which were authentically posttranslationally processed. Both VSV-expressed HCV E1-E2 glycoproteins were found to form noncovalently linked heterodimers and appeared to be correctly folded, as confirmed by coimmunoprecipitation analysis using conformationally sensitive anti-HCV-E2 monoclonal antibodies (MAbs). Intravenous or intraperitoneal immunization of BALB/c mice with VSV-C/E1/E2 or VSV⌬G-C/E1/E2 resulted in significant and surprisingly comparable HCV core or E2 antibody responses compared to those of control mice. In addition, both virus types generated HCV C-, E1-, or E2-specific gamma interferon (IFN-␥)-producing CD8 ؉ T cells, as determined by enzyme-linked immunospot (ELISPOT) analysis. Mice immunized with VSV⌬G-C/E1/E2 were also protected against the formation of tumors expressing HCV E2 (CT26-hghE2t) and exhibited CT26-hghE2t-specific IFN-␥-producing and E2-specific CD8 ؉ T-cell activity. Finally, recombinant vaccinia virus (vvHCV.S) expressing the HCV structural proteins replicated at significantly lower levels when inoculated into mice immunized with VSV-C/E1/E2 or VSV⌬G-C/E1/E2, but not with control viruses. Our data therefore illustrate that potentially safer replication-defective VSV can be successfully engineered to express high levels of antigenically authentic HCV glycoproteins. In addition, this strategy may therefore serve in effective vaccine and immunotherapy-based approaches to the treatment of HCV-related disease.

Replication-Competent Recombinant Vesicular Stomatitis Virus Encoding Hepatitis C Virus Envelope Proteins

“…Although recombinant VSV encoding HCV envelope proteins has been generated as a surrogate model for HCV infection and a vaccine vector (9,35), recombinant VSV generated in rodent cells possessing the chimeric E1 and/or E2 proteins has been shown to be noninfectious in a human hepatoma cell line that is susceptible to HCVpp infection (9). In this study, we successfully generated infectious recombinant and pseudotype VSVs incorporating unmodified E1 and E2 proteins in hepatic and nonhepatic human cell lines.…”

Preclinical safety and activity of recombinant VSV‐IFN‐β in an immunocompetent model of squamous cell carcinoma of the head and neck

“…Viruses were diluted in sterile normal saline to the desired concentration and kept on ice until use for in vitro and in vivo experiments. Virus titer was verified by 50% tissue culture infective dose (TCID 50 ) titration on VERO or BHK-21 cells (for in vivo safety and biodistribution experiments) or by plaque dilution (for in vitro and in vivo efficacy experiments), as previously described (22, 23) .…”

Current status of a hepatitis C vaccine: Encouraging results but significant challenges ahead

“…Other viral vectors such as vesicular stomatitis virus (VSV) and Semliki Forest virus (SFV) are available, but in the HCV context, these have only been tested in murine models for immunogenicity [26,27]. Despite the encouraging results seen in the study by Folgori et al [24••], future vaccine candidates will need to address the frequent immune escape by HCV.…”