Immunogenicity of nonreplicating recombinant vaccinia expressing HLA-A201 targeted or complete MART-1/Melan-A antigen

Abstract

The effect on immunogenicity of different tumor T cell epitope formulations was evaluated in vitro using nonreplicating recombinant vaccinia vector expressing two forms of the melanoma -associated MART -1 / Melan -A antigen. The first recombinant virus expressed a minigene encoding a fusion product between an endoplasmic reticulum ( ER ) -targeting signal and the HLA -A201 binding 27 -35 peptide. The second viral construct encoded the complete MART -1 / Melan -A protein. The capacity of HLA -A201 cells infected with either viral construct to generate and to stimulate MART -1 / Melan -A 27 -35 specific cytotoxic T -lymphocytes ( CTL ) , was comparatively characterized. The results obtained here with a tumor antigen confirmed the capacity of vaccinia virus -encoded ERminigene to generate a very strong antigenic signal. In cytotoxicity assays, recognition of target cells infected with high amounts of both recombinant viruses with activated specific CTL clones, resulted in similar lytic activity. With regard to calcium mobilization, TCR down -regulation, IFN -release, and T cell proliferation assays, the targeted epitope elicited 10 -to 1000 -fold stronger responses. Remarkably, the immunogenic difference between the two formulations, in their respective capacity to generate CTL from naive HLA -A2 peripheral blood mononuclear cells in vitro as measured by tetramer detection, was lower ( 2 -to 3 -fold ) .

Oncolytic viral therapies

“…In one study, 299 recombinant vaccinia virus was constructed in an effort to enhance the immunogenicity of transfected melanoma cells. The virus expressed a minigene encoding a fusion product that combined an endoplasmic reticulum (ER) targeting signal and the HLA-A201 binding 27-35 peptide.…”

Biased epitope selection by recombinant vaccinia-virus (rVV)-infected mature or immature dendritic cells

“…1,2 In natural conditions, DC most likely present exogenous Ag up-take from dead cells. 3,4 However, for therapeutic purposes, endogenous presentation of Ag encoded by viral vectors infecting DC has been proposed in murine 5 and human [6][7][8][9] models. This strategy of Ag delivery can induce human leukocyte antigen (HLA) class I-and class II-associated immune responses and may represent a potent immunization tool inducing prolonged Ag-specific stimulation within cells capable of powerful costimulation.…”

Clinical development directions in oncolytic viral therapy

“…The immunogenic properties were exploited in the production of smallpox vaccine, leading to the eradication of smallpox. In one study, 154 recombinant vaccinia virus was constructed in an effort to enhance the immunogenicity of transfected melanoma cells. The virus expressed a minigene encoding a fusion product that combined an endoplasmic reticulum-targeting signal and the HLA-A201 binding 27-35 peptide.…”