DNA Immunization of HLA Transgenic Mice with a Plasmid Expressing Mycobacterial Heat Shock Protein 65 Results in HLA Class I- and II-Restricted T Cell Responses That Can Be Augmented by Cytokines

Abstract

Infection with Mycobacterium tuberculosis (MTB) remains a major cause of morbidity and mortality world-wide. An effective vaccination strategy is the immunization with plasmid DNA (pDNA), expressing an antigen (Ag) from a pathogen in vivo, which results in specific immune response against the encoded protein as well as the pathogen itself or cells infected with it. To test the ability to induce HLA-restricted T cell immune response against a mycobacterial antigen in humans by pDNA vaccination, we have used transgenic mice that express HLA class I (A*0201/Kb) or HLA class II (DRB1*0301) molecules. pDNA immunization with mycobacterial heat shock protein 65 (Mhsp65)-expressing plasmid (P3M.65) resulted in HLA-II-restricted, Ag-specific T cell-mediated immune responses characterized by proliferation and cytokine production. These T cell responses could be further augmented by the coinjection of P3M.65 and plasmid expressing murine GM-CSF. Furthermore, coimmunizing HLA-I transgenic mice with P3M.65 and a plasmid expressing murine IFN-gamma induced a specific cytotoxic T lymphocyte response restricted by HLA-A2. These results represent the first evidence of a concomitant in vivo induction of HLA class I- as well as class II-restricted T cell responses by pDNA immunization, which is induced or augmented by the codelivery of cytokine-expressing plasmids, supporting its potential use in clinical trials.

Marked Enhancement of the Antigen-Specific Immune Response by Combining Plasmid DNA-Based Immunization with a Schiff Base-Forming Drug

“…Genes used in this study included the Epstein-Barr virus (EBV) nuclear antigen 4 (EBNA-4) and mycobacterial heat shock protein 65 (Mhsp65) genes, which were used as antigens, and mouse GM-CSF and IFN-␥, which were chosen as immunostimulatory cytokines. Details about the subcloning and testing of these plasmids have been published elsewhere (3,5).…”

“…HLA-A‫/1020ء‬K b transgenic mice (kindly provided by L. Sherman, Scripps Laboratories, San Diego, Calif.) used in this study have been described previously (40). This strain was used to enable the measurement of the cytotoxic T-cell response to a defined T-cell epitope restricted by HLA-A2 (4,5). The surface expression of HLA-A‫/1020ء‬K b was confirmed by using an HLA-A‫-1020ء‬ specific fluorescein isothiocyanate-conjugated monoclonal antibody (One Lambda, Canoga Park, Calif.) and assessed by flow cytometry using FACScan (Becton Dickinson & Co., Mountain View, Calif.).…”

“…These strategies include modification of the mode of delivery, targeting of the antigens, and coadministration of immunostimulatory genes or DNA sequences (3,5,8,11,12,15,20,25,26,34,41,43).…”

Protective Efficacy of a DNA Influenza Virus Vaccine Is Markedly Increased by the Coadministration of a Schiff Base-Forming Drug

“…Although limited information exists on the efficacy of pDNA immunization in humans, effective pDNA immunization has been achieved in both humanized animal models and in clinical studies in patients as well as volunteers (2,5,17,33). The molecular mechanism by which tucaresol exerts its immunopotentiating effects remains to be defined.…”

Auditing Protein Therapeutics Management by Professional APCs: Toward Prevention of Immune Responses against Therapeutic Proteins

“…Such models for vaccine development include transgenic animals with human MHC molecules designed especially to bridge the gap between human and mouse systems (53,54). Interestingly, direct correlations of T cell responses between those observed in humans and those in immunized transgenic mice have lead to the routine use of such models in preclinical studies (55)(56)(57)(58). MHC transgenics are, however, not sufficiently suitable for studying a break in tolerance as observed in the case of therapy with human autologous proteins like insulin, IFNa2, and human tissue plasminogen activator, because they are not tolerized to such proteins in the course of their development.…”