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John J Donnelly

Publications and source records attributed to John J Donnelly.

9 recordsLinked to original sources
PubMed2006

Evaluation of human immunodeficiency virus type 1 subtype C gag, pol, and gagpol DNA and alphavirus replicon vaccines.

The worldwide HIV-1 vaccine research endeavor is focused increasingly on subtype C, which is now the predominant strain of the present HIV/AIDS epidemic. Expression cassettes of HIV-1 subtype C gag, pol and versions of gagpol fusion cassettes were constructed and evaluated for their relative abilities to induce cellular immune responses in mice. Animals were vaccinated with DNA or alphavirus replicon particle-based vaccines and cellular immune responses were measured by flow cytometry. Five new major histocompatibility complex (MHC) class I-restricted T cell epitopes in subtype C Gag and Pol were identified. Although two CD8(+) T cell epitopes within Gag were immunodominant in BALB/c and CB6F1 mice, the overall breadth of the T cell responses in mice immunized with plasmids or recombinant alphavirus replicon particles encoding gagpol fusion genes was improved over single antigen genes (i.e. gag or pol alone). The patterns of epitope dominance were consistent among mice although there were variations observed between different animals in the relative contributions of the various epitopes to the total response. These data are consistent with observations in non-human primates (Otten GR, Schaefer M, Doe B, Liu H, Magede JZ, Donnelly J, et al. Potent immunogenicity of an HIV-1 gag-pol fusion DNA vaccine delivered by in vivo electroporation. Vaccine 2005, in press) and support a subtype C in-frame gagpol fusion gene vaccine.

AIDS Vaccines↗
PubMed2006

Antibody responses against HIV in rhesus macaques following combinations of mucosal and systemic immunizations with chimeric alphavirus-based replicon particles.

Mucosal and systemic transmission of HIV is prevalent. Therefore, mucosal followed by parenteral immunizations with chimeric vs. complete alphavirus-based replicon particles, encoding an HIV envelope glycoprotein, were tested. Female rhesus macaques were immunized intranasally and then intramuscularly. Following the immunizations, enhanced mucosal and systemic antibody responses were detected with the chimeric compared to the complete replicon particles. Although similar proportions of the same peripheral blood monocyte lineage target cells were infected with the chimeric vs. the complete replicon particles, the latter resulted in enhanced expression of the gene of interest, suggesting a possible mechanism of the enhanced immunogenicity.

Administration, Intranasal↗
PubMed2005

Development of V2-deleted trimeric envelope vaccine candidates from human immunodeficiency virus type 1 (HIV-1) subtypes B and C.

The urgent need for a vaccine against HIV/AIDS requires that multiple strategies be employed and evaluated in a clinical setting. V2-loop deleted trimeric envelope (Env) immunogens (protein and DNA) from subtypes B and C human immunodeficiency virus type 1 (HIV-1) strains were produced for ongoing and future clinical evaluations with other HIV antigens, adjuvants and deliveries.

AIDS Vaccines↗
PubMed2005

DNA vaccines: progress and challenges.

In the years following the publication of the initial in vivo demonstration of the ability of plasmid DNA to generate protective immune responses, DNA vaccines have entered into a variety of human clinical trials for vaccines against various infectious diseases and for therapies against cancer, and are in development for therapies against autoimmune diseases and allergy. They also have become a widely used laboratory tool for a variety of applications ranging from proteomics to understanding Ag presentation and cross-priming. Despite their rapid and widespread development and the commonplace usage of the term "DNA vaccines," however, the disappointing potency of the DNA vaccines in humans underscores the challenges encountered in the efforts to translate efficacy in preclinical models into clinical realities. This review will provide a brief background of DNA vaccines including the insights gained about the varied immunological mechanisms that play a role in their ability to generate immune responses.

Animals↗
PubMed2005

Evaluation of envelope vaccines derived from the South African subtype C human immunodeficiency virus type 1 TV1 strain.

Human immunodeficiency virus type 1 (HIV-1) subtype C infections are on the rise in Sub-Saharan Africa and Asia. Therefore, there is a need to develop an HIV vaccine capable of eliciting broadly reactive immune responses against members of this subtype. We show here that modified HIV envelope (env) DNA vaccines derived from the South African subtype C TV1 strain are able to prime for humoral responses in rabbits and rhesus macaques. Priming rabbits with DNA plasmids encoding V2-deleted TV1 gp140 (gp140TV1DeltaV2), followed by boosting with oligomeric protein (o-gp140TV1DeltaV2) in MF59 adjuvant, elicited higher titers of env-binding and autologous neutralizing antibodies than priming with DNA vaccines encoding the full-length TV1 env (gp160) or the intact TV1 gp140. Immunization with V2-deleted subtype B SF162 env and V2-deleted TV1 env together using a multivalent vaccine approach induced high titers of oligomeric env-binding antibodies and autologous neutralizing antibodies against both the subtypes B and C vaccine strains, HIV-1 SF162 and TV1, respectively. Low-level neutralizing activity against the heterologous South African subtype C TV2 strain, as well as a small subset of viruses in a panel of 13 heterologous primary isolates, was observed in some rabbits immunized with the V2-deleted vaccines. Immunization of rhesus macaques with the V2-deleted TV1 DNA prime/protein boost also elicited high titers of env-binding antibodies and moderate titers of autologous TV1 neutralizing antibodies. The pilot-scale production of the various TV1 DNA vaccine constructs and env proteins described here should provide an initial platform upon which to improve the immunogenicity of these subtype C HIV envelope vaccines.

AIDS Vaccines↗
PubMed2003

Mechanisms of increased immunogenicity for DNA-based vaccines adsorbed onto cationic microparticles.

Investigation into the mechanism of action of vaccine adjuvants provides opportunities to define basic immune principles underlying the induction of strong immune responses and insights useful for the rational development of subunit vaccines. A novel HIV vaccine composed of plasmid DNA-encoding p55 gag formulated with poly-lactide-co-glycolide microparticles (PLG) and cetyl trimethyl ammonium bromide (CTAB) elicits both serum antibody titers and cytotoxic lymphocyte activity in mice at doses two orders of magnitude lower than those required for comparable response to plasmid DNA in saline. Using this model, we demonstrated the increase in potency requires the DNA to be complexed to the PLG-CTAB microparticles. Furthermore, the PLG-CTAB-DNA formulation increased the persistence of DNA at the injection site, recruited mononuclear phagocytes to the site of injection, and activated a population of antigen presenting cells. Intramuscular immunization with the PLG-CTAB-DNA complex induced antigen expression at both the injection site and the draining lymph node. These findings demonstrate that the PLG-CTAB-DNA formulation exhibits multiple mechanisms of immunopotentiation.

AIDS Vaccines↗
PubMed2003

Expression and immunogenicity of sequence-modified human immunodeficiency virus type 1 subtype B pol and gagpol DNA vaccines.

Control of the worldwide AIDS pandemic may require not only preventive but also therapeutic immunization strategies. To meet this challenge, the next generation of human immunodeficiency virus type 1 (HIV-1) vaccines must stimulate broad and durable cellular immune responses to multiple HIV antigens. Results of both natural history studies and virus challenge studies with macaques indicate that responses to both Gag and Pol antigens are important for the control of viremia. Previously, we reported increased Rev-independent expression and improved immunogenicity of DNA vaccines encoding sequence-modified Gag derived from the HIV-1(SF2) strain (J. zur Megede, M. C. Chen, B. Doe, M. Schaefer, C. E. Greer, M. Selby, G. R. Otten, and S. W. Barnett, J. Virol. 74: 2628-2635, 2000). Here we describe results of expression and immunogenicity studies conducted with novel sequence-modified HIV-1(SF2) GagPol and Pol vaccine antigens. These Pol antigens contain deletions in the integrase coding region and were mutated in the reverse transcriptase (RT) coding region to remove potentially deleterious enzymatic activities. The resulting Pol sequences were used alone or in combination with sequence-modified Gag. In the latter, the natural translational frameshift between the Gag and Pol coding sequences was either retained or removed. Smaller, in-frame fusion gene cassettes expressing Gag plus RT or protease plus RT also were evaluated. Expression of Gag and Pol from GagPol fusion gene cassettes appeared to be reduced when the HIV protease was active. Therefore, additional constructs were evaluated in which mutations were introduced to attenuate or inactivate the protease activity. Nevertheless, when these constructs were delivered to mice as DNA vaccines, similar levels of CD8(+) T-cell responses to Gag and Pol epitopes were observed regardless of the level of protease activity. Overall, the cellular immune responses against Gag induced in mice immunized with multigenic gagpol plasmids were similar to those observed in mice immunized with the plasmid encoding Gag alone. Furthermore, all of the sequence-modified pol and gagpol plasmids expressed high levels of Pol-specific antigens in a Rev-independent fashion and were able to induce potent Pol-specific T- and B-cell responses in mice. These results support the inclusion of a gagpol in-frame fusion gene in future HIV vaccine approaches.

AIDS Vaccines↗
PubMed2002

Purification and characterization of oligomeric envelope glycoprotein from a primary R5 subtype B human immunodeficiency virus.

Human immunodeficiency virus (HIV) continues to be a major public health problem throughout the world, with high levels of mortality and morbidity associated with AIDS. Considerable efforts to develop an effective vaccine for HIV have been directed towards the generation of cellular, humoral, and mucosal immune responses. A major emphasis of our work has been toward the evaluation of oligomeric (o-gp140) forms of the HIV type 1 (HIV-1) envelope protein for their ability to induce neutralizing antibody responses. We have derived stable CHO cell lines expressing o-gp140 envelope protein from the primary non-syncytium-inducing (R5) subtype B strain HIV-1(US4). We have developed an efficient purification strategy to purify oligomers to near homogeneity. Using a combination of three detectors measuring intrinsic viscosity, light scattering, and refractive index, we calculated the molecular mass of the oligomer to be 474 kDa, consistent with either a trimer or a tetramer. The hydrodynamic radius (R(h)) of o-gp140 was determined to be 8.40 nm, compared with 5.07 nm for the monomer. The relatively smaller R(h) of the oligomer suggests that there are indeed differences between the foldings of o-gp140 and gp120. To assess the structural integrity of the purified trimers, we performed a detailed characterization of the glycosylation profile of o-gp140, its ability to bind soluble CD4, and also its ability to bind to a panel of monoclonal antibodies with known epitope specificities for the CD4 binding site, the CD4 inducible site, the V3 loop, and gp41. Immunogenicity studies with rabbits indicated that the purified o-gp140 protein was highly immunogenic and induced high-titer, high-avidity antibodies directed predominantly against conformational epitopes. These observations confirm the structural integrity of purified o-gp140 and its potential as a vaccine antigen.

AIDS Vaccines↗