Comparative Immunogenicity in Rabbits of the Polypeptides Encoded by the 5′ Terminus of Hepatitis C Virus RNA

Abstract

Recent studies on the primate protection from HCV infection stressed the importance of immune response against structural viral proteins. Strong immune response against nucleocapsid (core) protein was difficult to achieve, requesting further experimentation in large animals. Here, we analyzed the immunogenicity of core aa 1–173, 1–152, and 147–191 and of its main alternative reading frame product F-protein in rabbits. Core aa 147–191 was synthesized; other polypeptides were obtained by expression in E. coli. Rabbits were immunized by polypeptide primes followed by multiple boosts and screened for specific anti-protein and anti-peptide antibodies. Antibody titers to core aa 147–191 reached 105; core aa 1–152, 5 × 105; core aa 1–173 and F-protein, 106. Strong immunogenicity of the last two proteins indicated that they may compete for the induction of immune response. The C-terminally truncated core was also weakly immunogenic on the T-cell level. To enhance core-specific cellular response, we immunized rabbits with the core aa 1–152 gene forbidding F-protein formation. Repeated DNA immunization induced a weak antibody and sustained proliferative response of broad specificity confirming a gain of cellular immunogenicity. Epitopes recognized in rabbits overlapped those in HCV infection. Our data promotes the use of rabbits for the immunogenicity tests of prototype HCV vaccines.

Reciprocal Inhibition of Immunogenic Performance in Mice of Two Potent DNA Immunogens Targeting HCV-Related Liver Cancer

“…In Series I, we assessed the immunogenicity of the expression optimized HCV Core152opt. Splenocytes collected by the experimental endpoint were assessed for the capacity to produce IFN-γ, IL-2 and TNF-α alone and in combination in response to stimulation with pool of peptides encompassing aa 61-175 of HCV core ( Supplementary Table S1 ) recognized in mice [ 36 , 48 ]. In Core152opt DNA-immunized mice, we registered potent response characterized by secretion of IL-2, dual secretion of IFN-γ/TNF-α and triple secretion of IFN-γ/ IL-2/TNF-α by CD4+ T cells, while Core191v immunized mice responded by only by production of IFN-γ ( Figure 2 A,C).…”

The Immunogenicity in Mice of HCV Core Delivered as DNA Is Modulated by Its Capacity to Induce Oxidative Stress and Oxidative Stress Response

“…Repeated attempts to induce potent anti-core immune response met with difficulties, even when using viral vectors [5,6,7,8]. HCV core was defined as a poor cellular immunogen, both when delivered as DNA and as a protein [9,10,11,12,13,14]. We have shown that plasmids directing higher levels of core expression were less immunogenic than directing lower levels of HCV core expression [5].…”