RESUMO
The prophylactic efficacies of several multivalent replication-incompetent adenovirus serotype 5 (Ad5) vaccines were examined in rhesus macaques using an intrarectal high-dose simian immunodeficiency virus SIVmac239 challenge model. Cohorts of Mamu-A*01(+)/B*17(-) Indian rhesus macaques were immunized with one of several combinations of Ad5 vectors expressing Gag, Pol, Nef, and Env gp140; for comparison, a Mamu-A*01(+) cohort was immunized using the Ad5 vector alone. There was no sign of immunological interference between antigens in the immunized animals. In general, expansion of the antigen breadth resulted in more favorable virological outcomes. In particular, the order of efficacy trended as follows: Gag/Pol/Nef/Env approximately Gag/Pol > Gag approximately Gag/Pol/Nef > Nef. However, the precision in ranking the vaccines based on the study results may be limited by the cohort size, and as such, may warrant additional testing. The implications of these results in light of the recent discouraging results of the phase IIb study of the trivalent Ad5 HIV-1 vaccine are discussed.
Assuntos
Adenoviridae/imunologia , Vacinas contra a SAIDS/imunologia , Síndrome de Imunodeficiência Adquirida dos Símios , Vírus da Imunodeficiência Símia/imunologia , Vacinas contra a AIDS/imunologia , Adenoviridae/genética , Animais , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD4-Positivos/imunologia , Ensaios Clínicos Fase II como Assunto , Humanos , Macaca mulatta/imunologia , Macaca mulatta/virologia , Testes de Neutralização , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Síndrome de Imunodeficiência Adquirida dos Símios/prevenção & controle , Vírus da Imunodeficiência Símia/genética , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/imunologia , Carga Viral , Viremia/imunologiaRESUMO
Programmed Cell Death 1 (PD-1) plays a crucial role in immunomodulation. Binding of PD-1 to its ligand receptors down-regulates immune responses, and published reports suggest that this immune modulation is exploited in cases of tumor progression or chronic viral infection to evade immune surveillance. Thus, blockade of this signal could restore or enhance host immune functions. To test this hypothesis, we generated a panel of mAbs specific to human PD-1 that block PD ligand 1 and tested them for in vitro binding, blocking, and functional T cell responses, and evaluated a lead candidate in two in vivo rhesus macaque (Macaca mulatta) models. In the first therapeutic model, chronically SIV-infected macaques were treated with a single infusion of anti-PD-1 mAb; viral loads increased transiently before returning to, or falling below, pretreatment baselines. In the second prophylactic model, naive macaques were immunized with an SIV-gag adenovirus vector vaccine. Induced PD-1 blockade caused a statistically significant (p<0.05) increase in the peak percentage of T cells specific for the CM9 Gag epitope. These new results on PD-1 blockade in nonhuman primates point to a broader role for PD-1 immunomodulation and to potential applications in humans.
Assuntos
Antígenos CD/imunologia , Proteínas Reguladoras de Apoptose/antagonistas & inibidores , Proteínas Reguladoras de Apoptose/imunologia , Vacinas contra a SAIDS/imunologia , Síndrome de Imunodeficiência Adquirida dos Símios/imunologia , Síndrome de Imunodeficiência Adquirida dos Símios/prevenção & controle , Animais , Anticorpos Bloqueadores/metabolismo , Anticorpos Bloqueadores/fisiologia , Anticorpos Monoclonais/metabolismo , Anticorpos Monoclonais/fisiologia , Antígenos CD/metabolismo , Proteínas Reguladoras de Apoptose/metabolismo , Antígeno B7-H1 , Linhagem Celular , Doença Crônica , Humanos , Imunoglobulina G/fisiologia , Macaca mulatta , Camundongos , Camundongos Endogâmicos BALB C , Receptor de Morte Celular Programada 1 , Vacinas contra a SAIDS/administração & dosagem , Síndrome de Imunodeficiência Adquirida dos Símios/virologia , Carga ViralRESUMO
Results from Merck's phase II adenovirus type 5 (Ad5) gag/pol/nef test-of-concept trial showed that the vaccine lacked efficacy against human immunodeficiency virus (HIV) infection in a high-risk population. Among the many questions to be explored following this outcome are whether (i) the Ad5 vaccine induced the quality of T-cell responses necessary for efficacy and (ii) the lack of efficacy in the Ad5 vaccine can be generalized to other vector approaches intended to induce HIV type 1 (HIV-1)-specific T-cell responses. Here we present a comprehensive evaluation of the T-cell response profiles from cohorts of clinical trial subjects who received the HIV CAM-1 gag insert delivered by either a regimen with DNA priming followed by Ad5 boosting (n = 50) or a homologous Ad5/Ad5 prime-boost regimen (n = 70). The samples were tested using a statistically qualified nine-color intracellular cytokine staining assay measuring interleukin-2 (IL-2), tumor necrosis factor alpha, macrophage inflammatory protein 1beta, and gamma interferon production and expression of CD107a. Both vaccine regimens induced CD4(+) and CD8(+) HIV gag-specific T-cell responses which variably expressed several intracellular markers. Several trends were observed in which the frequencies of HIV-1-specific CD4(+) T cells and IL-2 production from antigen-specific CD8(+) T cells in the DNA/Ad5 cohort were more pronounced than in the Ad5/Ad5 cohort. Implications of these results for future vaccine development will be discussed.
Assuntos
Adenoviridae/metabolismo , Genes gag/genética , Linfócitos T/virologia , Vacinas contra a AIDS/metabolismo , Linfócitos T CD4-Positivos/virologia , Linfócitos T CD8-Positivos/virologia , Quimiocina CCL4/biossíntese , Estudos de Coortes , DNA/metabolismo , Humanos , Interleucina-2/biossíntese , Proteína 1 de Membrana Associada ao Lisossomo/biossíntese , Modelos Biológicos , Fenótipo , Linfócitos T/metabolismo , Fator de Necrose Tumoral alfa/biossínteseRESUMO
Quantitative analysis of cell-mediated immune responses induced by candidate HIV vaccines requires robust procedures for collecting and processing human peripheral mononuclear blood cells (PBMCs). We evaluated several parameters in order to optimize a sample handling process that would be suitable for a multicenter clinical trial. Among the findings, systematic increases in the magnitude of IFN-gamma ELISpot responses were observed when the time from blood collection to PBMC freezing was reduced to <12 h. By implementing these improvements within an ongoing clinical trial, the estimated immunologic response rates to an adenovirus- based HIV vaccine increased by more than 20 percentage points to approximately 80% of the vaccine recipients against any of the vaccine antigens and the average levels of T cell response improved more than 3-fold. These studies establish the importance of optimal conditions for PBMC collection and handling to the success of a clinical development program.
Assuntos
Vacinas contra a AIDS/imunologia , Leucócitos Mononucleares/imunologia , Manejo de Espécimes , Vacinas contra a AIDS/uso terapêutico , Adenoviridae/genética , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Células Cultivadas , Ensaios Clínicos como Assunto , Criopreservação , Ensaio de Imunoadsorção Enzimática , Infecções por HIV/prevenção & controle , Soronegatividade para HIV , Humanos , Imunidade Celular , Interferon gama/imunologia , Linfócitos T/imunologia , Fatores de TempoRESUMO
Currently, there are numerous candidate HIV vaccines aimed at inducing T-cell mediated immune responses against HIV. To assess the immunogenicity of such vaccines, a reliable T cell assay must be utilized and typically one of the following assays is chosen for this purpose: bulk culture CTL, MHC I tetramer staining, IFN-gamma ELISPOT, or IFN-gamma intracellular cytokine staining. In this paper we report a comparison of the T cell responses detected by each assay in a large cohort of healthy normal volunteers vaccinated with adenovirus serotype 5 expressing HIV gag. Using stringently validated formats of each of these assays and pools of overlapping HIV gag peptides, we demonstrate that there is a high degree of correlation between all four of the common T cell assays, but inherent differences in the sensitivity of each assay to detect responders. In this study, the ELISPOT assay is shown to have the greatest sensitivity in detecting vaccine responses, while the ICS assay, although less sensitive, has the advantage of providing additional information on the phenotype of the responding cells.
Assuntos
Vacinas contra a AIDS/imunologia , Produtos do Gene gag/imunologia , Infecções por HIV/prevenção & controle , Linfócitos T/fisiologia , Adenoviridae , Adolescente , Adulto , Feminino , Antígenos HIV/imunologia , HIV-1 , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The prophylactic efficacy of DNA and replication-incompetent adenovirus serotype 5 (Ad5) vaccine vectors expressing simian immunodeficiency virus (SIV) Gag was examined in rhesus macaques using an SIVmac239 challenge. Cohorts of either Mamu-A*01(+) or Mamu-A*01(-) macaques were immunized with a DNA prime-Ad5 boost regimen; for comparison, a third cohort consisting of Mamu-A*01(+) monkeys was immunized using the Ad5 vector alone for both prime and boost. All animals, along with unvaccinated control cohorts of Mamu-A*01(+) and Mamu-A*01(-) macaques, were challenged intrarectally with SIVmac239. Viral loads were measured in both peripheral and lymphoid compartments. Only the DNA prime-Ad5-boosted Mamu-A*01(+) cohort exhibited a notable reduction in peak plasma viral load (sevenfold) as well as in early set-point viral burdens in both plasma and lymphoid tissues (10-fold) relative to those observed in the control monkeys sharing the same Mamu-A*01 allele. The degree of control in each animal correlated with the levels of Gag-specific immunity before virus challenge. However, virus control was short-lived, and indications of viral escape were evident as early as 6 months postinfection. The implications of these results in vaccine design and clinical testing are discussed.