The effect of helper epitopes and cellular localization of an antigen on the outcome of gene gun DNA immunization

Abstract

In DNA vaccination, CD4(+) T-cell help can be enhanced by fusion of a gene encoding an immunization protein with a foreign gene or its part providing T(h) epitopes. To study the effect of helper epitope localization in a protein molecule, the influence of the vicinity of the helper epitope, and the impact of chimeric protein cellular localization, we fused the helper epitope p30 from tetanus toxin (TT, aa 947-967) with the N- or C-terminus of the mutated E7 oncoprotein (E7GGG) of human papillomavirus type 16, enlarged the p30 epitope with the flanking residues containing potential protease-sensitive sites and altered the cellular localization of the fusion constructs by signal sequences. The p30 epitope enhanced the E7-specific response, but only in constructs without added signal sequences. After localization of the fusion proteins into the endoplasmic reticulum and endo/lysosomal compartment, the TT-specific T(h)2 response was increased. The synthetic Pan DR epitope (PADRE) induced a stronger E7-specific response than the p30 epitope and its stimulatory effect was not limited to nuclear/cytoplasmic localization of the E7 antigen. These results suggest that in the optimization of immune responses by adding helper epitopes to DNA vaccines delivered by the gene gun, the cellular localization of the antigen needs to be taken into account.

In silicodesign of a DNA-based HIV-1 multi-epitope vaccine for Chinese populations

“…Several reports indicated that Th epitopes are capable of increasing the immunogenicity of CTL epitope-based vaccines, 34 and, as such, some universal Th epitopes were previously incorporated into such vaccines. 34,35 In this work, Th epitopes were included as part of the multi-epitope vaccine to induce better immune responses.…”

“…34,35 In this work, Th epitopes were included as part of the multi-epitope vaccine to induce better immune responses. In contrast other studies, HIV-1-specific Th epitopes, rather than universal Th epitopes, were chosen for 2 reasons.…”

Combined Cancer Immunotherapy Against Aurora Kinase A

“…31 Cellular localization of the Aurka protein was changed by the sorting sequences of the LAMP-1 protein that have been published to enhance immunogenicity of other antigens. 31 Cellular localization of the Aurka protein was changed by the sorting sequences of the LAMP-1 protein that have been published to enhance immunogenicity of other antigens.…”

“…This combined immunotherapy significantly inhibited the growth of TC-1induced tumors, but only when a single dose of anti-CD25 was applied (Fig. 31 Similar to the PADRE.mutAurka gene in preventive immunization, the PADRE.E7GGG gene reduced tumor growth only in combination with a single anti-CD25 dose (Fig. In therapeutic immunization against TC-1 cells, when the PADRE.mutAurka DNA vaccine was applied 3, 7, and 10 days after TC-1 inoculation and antibody against CD25 was injected on days of immunization or 2 days before TC-1 inoculation, DNA vaccination alone or combined with anti-CD25 did not influence tumor growth (Fig.…”

“…For all amplifications, Phusion High-Fidelity DNA Polymerase (Finnzymes, Espoo, Finland) 31 was used, and the constructed genes were verified by sequencing.…”