A Decaepitope Polypeptide Primes for Multiple CD8+ IFN-γ and Th Lymphocyte Responses: Evaluation of Multiepitope Polypeptides as a Mode for Vaccine Delivery

Abstract

Proteins are generally regarded as ineffective immunogens for CTL responses. We synthesized a 100-mer decaepitope polypeptide and tested its capacity to induce multiple CD8+ IFN-γ and Th lymphocyte (HTL) responses in HLA transgenic mice. Following a single immunization in the absence of adjuvant, significant IFN-γ in vitro recall responses were detected for all epitopes included in the construct (six A2.1-, three A11-restricted CTL epitopes, and one universal HTL epitope). Immunization with truncated forms of the decaepitope polypeptide was used to demonstrate that optimal immunogenicity was associated with a size of at least 30–40 residues (3–4 epitopes). Solubility analyses of the truncated constructs were used to identify a correlation between immunogenicity for IFN-γ responses and the propensity of these constructs to form particulate aggregates. Although the decaepitope polypeptide and a pool of epitopes emulsified in IFA elicited similar levels of CD8+ responses using fresh splenocytes, we found that the decaepitope polypeptide more effectively primed for in vitro recall CD8+ T cell responses. Finally, immunogenicity comparisons were also made between the decaepitope polypeptide and a corresponding gene encoding the same polypeptide delivered by naked DNA immunization. Although naked DNA immunization induced somewhat greater direct ex vivo and in vitro recall responses 2 wk after a single immunization, only the polypeptide induced significant in vitro recall responses 6 wk following the priming immunization. These studies support further evaluation of multiepitope polypeptide vaccines for induction of CD8+ IFN-γ and HTL responses.

Multiepitope peptide-loaded virus-like particles as a vaccine against hepatitis B virus–related hepatocellular carcinoma #

“…39 The immunoenhancement effects could be ascribed to Th epitopes in the carrier core protein 31 and the polymeric or particulate nature of VLPs, which could be taken up rapidly and processed efficiently by antigen-presenting cells. 40 The presence of junctional epitopes may elicit an undesired immunodominance effect, completely silencing the recognition of the desired epitopes. 41 Great efforts have been made to avoid junctional epitopes by adopting suitable flanking spacers.…”

A CD8+ T Cell Heptaepitope Minigene Vaccine Induces Protective Immunity againstChlamydia pneumoniae

“…Incorrect epitope position, aliphatic or aromatic residues flanking the C terminus of an epitope, and the creation of junctional epitopes, can all adversely affect the magnitude and frequency of CTL responses (29,31,37). Thus, the sequence of CpnCTL7 was optimized by defining the most favorable order of epitopes and the type of spacers that could maximize proper processing and minimize the creation of neoepitopes.…”

“…Subunit constructs comprising multiple epitopes can be immunogenic (28,29,31,32) and protective (25)(26)(27)30) when delivered using plasmid DNA, infectious live vectors, or as recombinant or synthetic polypeptides. We opted for the DNA plasmid format because they are inexpensive, noninfectious, and can be readily optimized to enhance immunogenicity and protective efficacy.…”

“…Of the available vaccine technologies, the multiepitope-based subunit approach is perhaps the best suited to mimic or augment wholeorganism-induced immunity and prevent potential immunopathogenic or suppressive responses by incorporating into a construct a mix of protective T and B cell epitopes from multiple Ags. Studies in other pathogen and tumor model systems indicate that CD8 ϩ T cell multiepitope constructs can simultaneously induce responses against different CTL determinants when delivered either as DNA plasmids, recombinant infectious vectors, or as polypeptides (25)(26)(27)(28)(29)(30)(31)(32). However, few reports using this multiepitope-based approach have evaluated CD8…”

A melanoma multiepitope polypeptide induces specific CD8+ T-cell response

“…However, the presence of an immunodominant epitope may jeopardize an unbiased immune response to the mixture (16,31). A different multiepitope approach has been the use of a polypeptide composed of a string of ten epitopes (32). Studies in mice with multiepitope DNA-based vaccines containing melanoma sequences have focused attention to the importance of linkers as part of the recombinant complex (16).…”