RESUMEN
We examined the effect of two leader sequences, one from a transmembrane molecule (H2-L(d)) and another from a secreted molecule (rat KC chemokine), on the immunogenicity of DNA epitope vaccines. The chemokine leader enhanced vaccine immunogenicity, thus underscoring the importance of the leader sequence in DNA epitope vaccine design.
Asunto(s)
Epítopos/genética , Epítopos/inmunología , Señales de Clasificación de Proteína/genética , Vacunas de ADN/inmunología , Animales , Pruebas Inmunológicas de Citotoxicidad , Inmunización Secundaria/métodos , Interferón gamma/metabolismo , Interleucina-2/metabolismo , Ratones , Ratones Endogámicos BALB C , Linfocitos T/inmunología , Vacunación/métodos , Vacunas de ADN/administración & dosificación , Vacunas de ADN/genéticaRESUMEN
Immunization with naked plasmid DNA elicits strong cell-mediated immune responses. In the present study, we examine strategies to enhance epitope-specific cytotoxic T lymphocyte (CTL) responses using DNA constructs, expressing a minimal class I epitope of the gp120 of HIV-IIIB. Here, we evaluate the effect of CD4+ T cell (T(H)) epitope affinity for the MHC II molecule on the immunogenicity of our DNA vaccines. Our data indicate that a low-affinity T(H) epitope decreased the magnitude of the CTL responses. In addition, we observed decreased numbers of epitope-specific T helper cells and CTLs, as well as diminished cytokine secretion and proliferative responses. Thus, the immunogenicity of a DNA epitope vaccine can be modulated by altering the affinity of the T(H) epitope.
Asunto(s)
Epítopos de Linfocito T/inmunología , Genes MHC Clase II/inmunología , Linfocitos T Citotóxicos/inmunología , Vacunas de ADN/inmunología , Secuencia de Aminoácidos , Animales , Recuento de Linfocito CD4 , Linfocitos T CD8-positivos/inmunología , Radioisótopos de Cromo , Citocinas/metabolismo , Ensayo de Inmunoadsorción Enzimática , Femenino , Vectores Genéticos , Recuento de Linfocitos , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , Plásmidos/genética , Timidina/metabolismoRESUMEN
Female SJL/J mice, suffering from experimental autoimmune encephalomyelitis (EAE), were injected with 1 x 10(7) cells from a syngeneic fibroblast line transduced with a retroviral vector designed to encode proteolipid protein (101-157) targeted for secretion. A striking abrogation of both clinical and histological signs of disease resulted. The treatment was efficacious when given after the first or the third relapses, protected naive mice from challenge with spinal cord homogenate, and was dose dependent. This strategy was devised to provide a systemic, antigen-specific signal to pathogenic T cells in the absence of costimulation and, hence, render them anergic. Cytokine analyses of brain and spinal cord lymphocytes demonstrate that the treatment induces an antiinflammatory Th2 profile, indicating that this antigen-specific therapy acts by a cytokine-induced pathway. This study was designed for translation to the clinic. We envision using allogeneic transduced fibroblasts, encapsulated in a chamber, to deliver the antigen-specific signal. This will enable us to use one therapeutic cell line for all patients and to remove the device should the therapy exacerbate disease.
Asunto(s)
Proteínas de Unión al ADN/uso terapéutico , Terapia Genética , Esclerosis Múltiple/terapia , Factores de Transcripción/uso terapéutico , Animales , Línea Celular , Citocinas/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Modelos Animales de Enfermedad , Encefalomielitis Autoinmune Experimental/inducido químicamente , Encefalomielitis Autoinmune Experimental/terapia , Ensayo de Inmunoadsorción Enzimática/métodos , Femenino , Fibroblastos/virología , Vectores Genéticos , Ratones , Ratones Endogámicos , Prevención Secundaria , Análisis de Secuencia de Proteína , Linfocitos T/metabolismo , Factores de Tiempo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transducción Genética/métodos , Factores de Crecimiento Transformadores/metabolismoRESUMEN
Lentiviruses display surprisingly disparate clinical manifestations in their specific hosts, share complex genetic structures, and exhibit extensive diversity, particularly in their envelope genes. The envelope protein, gp135, of caprine arthritis-encephalitis virus (CAEV) has minimal primary sequence homology to gp120, the envelope protein of human immunodeficiency virus (HIV). Nevertheless, they bear certain similarities in that they both possess five variable regions, both are heavily glycosylated, and both share short sequence motifs. We establish a further relationship and demonstrate that some goats, infected with CAEV, possess gp135-specific antibodies which cross-react with gp120 from several HIV strains, provided the protein is expressed in insect cells. We show that, although the cross-reactivity of these immunoglobulins depends on the level of glycosylation, nevertheless, some antibodies recognize the protein epitopes on gp120, at least some of which are linear in character. Further characterization of this unexpected cross-reaction will define its potential therapeutic utility.