Induction of Broad CD4⁺and CD8⁺T-Cell Responses and Cross- Neutralizing Antibodies against Hepatitis C Virus by Vaccination with Th1-Adjuvanted Polypeptides Followed by Defective Alphaviral Particles Expressing Envelope Glycoproteins gpE1 and gpE2 and Nonstructural Proteins 3, 4, and 5

Abstract

Broad, multispecific CD4؉ and CD8 ؉ T-cell responses to the hepatitis C virus (HCV), as well as viruscross-neutralizing antibodies, are associated with recovery from acute infection and may also be associated in chronic HCV patients with a favorable response to antiviral treatment. and CD8؉ T-cell responses to E1E2 and NS345 was obtained by first priming with Th1-adjuvanted proteins and then boosting with chimeric, defective alphaviruses expressing these HCV genes. In addition, this prime/ boost regimen resulted in the induction of anti-E1E2 antibodies capable of cross-neutralizing heterologous HCV isolates in vitro. This vaccine formulation and regimen may therefore be optimal in humans for protection against this highly heterogeneous global pathogen.

Enhanced and Sustained CD8+ T Cell Responses with an Adenoviral Vector-Based Hepatitis C Virus Vaccine Encoding NS3 Linked to the MHC Class II Chaperone Protein Invariant Chain

“…We found that linkage of Ii to HCV NS3 enhanced, accelerated, and broadened the CD8 + T cell response in a similar manner as seen in the LCMV model (28,40). The Ad-IiNS3-induced CD8 + T cell frequencies shown in this study are, to our knowledge, considerably higher than any of the previously published frequencies obtained after vaccination with HCV NS proteins (17)(18)(19)(20). Moreover, these high CD8 + T cell frequencies were obtained after a single vaccination compared with other vaccination studies in which multiple heterologous prime boost vaccinations were required to reach even lower levels (20,21).…”

“…The current study further explored the benefits of the Ii linkage technology by applying it to an Ag of human disease relevance, HCV NS3, which moreover is well known for its low immunogenicity (17)(18)(19)(20). In this study, we show that the intrinsically poorly immunogenic Ag HCV NS3 benefits from the Ii technology mediating increased Ag presentation, and that this vaccination strategy led to responses markedly higher than what has previously been reported.…”

“…Despite strong evidence for the importance of cellular immunity in the combat against HCV infection, it has been a major challenge to design potent vaccines against HCV. The frequency of T cells directed toward the NS proteins of HCV observed in HCV vaccine studies range from 0.3% after vaccination with NS3/NS4A vaccine as measured after in vitro stimulation for 5-7 d to 0.9% of the CD8 + T cell population after three vaccinations with Th1-adjuvanted polypeptides and defective alpha-viral particles measured by ex vivo intracellular IFN-g production (17)(18)(19)(20). One of the few HCV vaccination strategies capable of inducing strong, broad, and multispecific T cell responses against the NS proteins of HCV (NS3-NS5) is the adenovirus prime and DNA boost vaccination regimen, which was evaluated in the chimpanzee model, and relatively high frequencies of CD4 + (0.5%) and CD8 + (1.0-1.5%) T cells directed against NS3-NS5 were found after the last vaccination (21).…”

“…Recently our laboratory found that linkage of the vaccine Ag to the murine invariant chain (Ii) can increase Ag presentation on MHC class I molecules resulting in enhanced, broadened, and prolonged CD8 + T cell responses (28). The modest results reported in the field of HCV vaccine imply that it is difficult to induce cellular immune responses to the NS proteins of HCV (17)(18)(19)(20)(21). We therefore hypothesized that an adenoviral-based vaccine encoding NS3 linked to Ii would improve the NS3-specific cellular responses.…”

Hepatitis C virus-specific cellular and humoral immune responses following immunization with a multi-epitope fusion protein

“…Recent studies have made great progress in developing many HCV vaccine candidates. These studies involved the use of recombinant HCV envelope glycoproteins gpE1 and gpE2 as vaccine antigens (17). The high yield of these vaccine antigens is very important for the evaluation of immune responses in vitro.…”