Chemical Conjugate TMV−Peptide Bivalent Fusion Vaccines Improve Cellular Immunity and Tumor Protection

Abstract

Chemical conjugation of CTL peptides to tobacco mosaic virus (TMV) has shown promise as a molecular adjuvant scaffold for augmentation of cellular immune responses to peptide vaccines. This study demonstrates the ease of generating complex multipeptide vaccine formulations using chemical conjugation to TMV for improved vaccine efficacy. We have tested a model foreign antigen target-the chicken ovalbumin-derived CTL peptide (Ova peptide), as well as mouse melanoma-associated CTL epitopes p15e and tyrosinase-related protein 2 (Trp2) peptides that are self-antigen targets. Ova peptide fusions to TMV, as bivalent formulations with peptides encoding additional T-help or cellular uptake via the integrin-receptor binding RGD peptide, showed improved vaccine potency evidenced by significantly enhanced numbers of antigen-reactive T cells measured by in vitro IFNgamma cellular analysis. We measured the biologically relevant outcome of vaccination in protection of mice from EG.7-Ova tumor challenge, which was achieved with only two doses of vaccine ( approximately 600 ng peptide) given without adjuvant. The p15e peptide alone or Trp2 peptide alone, or as a bivalent formulation with T-help or RGD uptake epitopes, was unable to stimulate effective tumor protection. However, a vaccine with both CTL peptides fused together onto TMV generated significantly improved survival. Interestingly, different bivalent vaccine formulations were required to improve vaccine efficacy for Ova or melanoma tumor model systems.

Replication and encapsidation of recombinant Turnip yellow mosaic virus RNA

“…Antigens displayed on VLPs are known to be more immunogenic than soluble antigen molecules, due to the highly ordered representation of antigen. Tobacco mosaic virus (TMV) has been successfully employed for this purpose (8,9). Another emerging application of plant viruses is their potential use as a vector for genetic medicine.…”

The Design of Polyvalent Therapeutics

“…maximal inhibitory concentrations (IC 50 values) from % 10 À6 m to lower, more potent values ( % 10 À8 m) over a narrow range of peptide densities. Moreover, the average inter-peptide distance at this transition (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50) matched the average separation between peptide-binding sites on the heptamer. [12] Previous theoretical studies had found that random heteropolymers recognize surfaces presenting multiple binding sites when the statistics characterizing the distribution of heteropolymer ligands along the polymer backbone and the density of surface binding sites were similar or "matched".…”

“…Enhancing immunogenicity: In recent years, engineered viruses have been used as novel scaffolds for the polyvalent display of antigens, [50][51][52][53][54] enabling the generation of both Tcell and antibody based immune responses without an adjuvant. Kaltgrad et al arrayed tetra-and hexasaccharides on the surface of cowpea mosaic virus.…”

Tobacco derived cancer vaccines for non-Hodgkin’s lymphoma: Perspectives and progress

“…51). And lastly, TMV virus itself has also been demonstrated to be an excellent peptide vaccine carrier, [48][49][50] extending its use beyond innate immune surveillance that keeps tumors in check, and possibly may mediate spontaneous regression. If indolent NHL are indeed subject to immune surveillance, it may explain why the control group (GM-CSF plus KLH) in both unsuccessful NHL Phase III trials had improved survival compared historically to chemotherapy alone, because of a general increase in non-specific immune activation.…”