RESUMEN
Although plasmid DNA vaccines induce potent cell-mediated immune responses and prime for antibody responses in experimental laboratory animals, their immunogenicity in humans has been less remarkable. A number of strategies have been proposed to improve the immunogenicity of these vaccines, including using novel means of vaccine delivery. In the present study, the immunogenicity of three different methods of intramuscular plasmid DNA administration was compared in cynomolgus monkeys: needle and syringe, Biojector 2000, and Mini-Ject. The elicited cellular and humoral immune responses were comparable in monkeys immunized using these different delivery techniques, suggesting that the needle-free approaches to vaccine administration do not significantly improve the immunogenicity of the plasmid DNA vaccine used in the study.
Asunto(s)
Inyecciones Intramusculares/métodos , Vacunas de ADN/administración & dosificación , Animales , Formación de Anticuerpos/inmunología , Citocinas/biosíntesis , Citocinas/genética , Ensayo de Inmunoadsorción Enzimática , Anticuerpos Anti-VIH/análisis , Anticuerpos Anti-VIH/biosíntesis , VIH-1/inmunología , Inmunidad Celular/inmunología , Inyecciones a Chorro , Macaca fascicularis , Masculino , Agujas , Plásmidos/genética , Plásmidos/inmunología , Jeringas , Linfocitos T/inmunologíaRESUMEN
Because the vaccine vectors currently being evaluated in human populations all have significant limitations in their immunogenicity, novel vaccine strategies are needed for the elicitation of cell-mediated immunity. The nonpathogenic, rapidly growing mycobacterium Mycobacterium smegmatis was engineered as a vector expressing full-length human immunodeficiency virus type 1 (HIV-1) HXBc2 envelope protein. Immunization of mice with recombinant M. smegmatis led to the expansion of major histocompatibility complex class I-restricted HIV-1 epitope-specific CD8(+) T cells that were cytolytic and secreted gamma interferon. Effector and memory T lymphocytes were elicited, and repeated immunization generated a stable central memory pool of virus-specific cells. Importantly, preexisting immunity to Mycobacterium bovis BCG had only a marginal effect on the immunogenicity of recombinant M. smegmatis. This mycobacterium may therefore be a useful vaccine vector.
Asunto(s)
Vacunas contra el SIDA/inmunología , Linfocitos T CD8-positivos/inmunología , Genes env , Proteína gp120 de Envoltorio del VIH/inmunología , VIH-1/inmunología , Mycobacterium smegmatis/genética , Animales , Vacunas Bacterianas/inmunología , Pruebas Inmunológicas de Citotoxicidad , Femenino , Inmunización , Memoria Inmunológica , Interferón gamma/biosíntesis , Ratones , Ratones Endogámicos BALB C , Mycobacterium bovis , Mycobacterium smegmatis/inmunología , Vacunas Sintéticas/inmunologíaRESUMEN
Gene transfer vectors based on recombinant adeno-associated virus (rAAV) are simple, versatile, and safe. While the conventional applications for rAAV vectors have focused on delivery of therapeutic genes, we have developed the system for delivery of vaccine antigens. In particular, we are interested in generating rAAV vectors for use as a prophylactic human immunodeficiency virus type 1 (HIV-1) vaccine. To that end, we constructed vaccine vectors that expressed genes from the simian immunodeficiency virus (SIV) for evaluation in the monkey SIV model. After a single intramuscular dose, rAAV/SIV vaccines elicited SIV-specific T cells and antibodies in macaques. Furthermore, immunized animals were able to significantly restrict replication of a live, virulent SIV challenge. These data suggest that rAAV vaccine vectors induced biologically relevant immune responses, and thus, warrant continued development as a viable HIV-1 vaccine candidate.
Asunto(s)
Dependovirus/genética , Vacunas contra el SIDAS/inmunología , Virus de la Inmunodeficiencia de los Simios/fisiología , Vacunas Sintéticas/inmunología , Replicación Viral , Animales , Dependovirus/inmunología , Vectores Genéticos , Antígenos de Histocompatibilidad Clase I/genética , Macaca mulatta , Pruebas de Neutralización , Vacunas de ADN/inmunologíaRESUMEN
Although recent evidence has confirmed the importance of cytotoxic T-lymphocyte (CTL) responses in controlling human immunodeficiency virus type 1 and simian immunodeficiency virus replication, the relevance of the epitopic breadth of those CTL responses remains unexplored. In the present study, we sought to determine whether vaccination can expand CTL populations which recognize a repertoire of viral epitopes that is greater than is typically generated in the course of a viral infection. We demonstrate that potent secondary CTL responses to subdominant epitopes are rapidly generated following a pathogenic simian-human immunodeficiency virus challenge of rhesus monkeys vaccinated with plasmid DNA or recombinant modified vaccinia virus Ankara vaccines. These data indicate that prior vaccination can increase the breadth of the CTL response that evolves after an AIDS virus infection.
Asunto(s)
Vacunas contra el SIDA/inmunología , Epítopos de Linfocito T/inmunología , Infecciones por VIH/inmunología , Vacunas contra el SIDAS/inmunología , Síndrome de Inmunodeficiencia Adquirida del Simio/inmunología , Linfocitos T Citotóxicos/inmunología , Animales , Infecciones por VIH/prevención & control , VIH-1/genética , VIH-1/inmunología , Humanos , Macaca mulatta , Síndrome de Inmunodeficiencia Adquirida del Simio/prevención & control , Virus de la Inmunodeficiencia de los Simios/genética , Virus de la Inmunodeficiencia de los Simios/inmunología , Vacunación , Vacunas de ADN/inmunologíaRESUMEN
Potent virus-specific cytotoxic T lymphocyte (CTL) responses elicited by candidate AIDS vaccines have recently been shown to control viral replication and prevent clinical disease progression after pathogenic viral challenges in rhesus monkeys. Here we show that viral escape from CTL recognition can result in the eventual failure of this partial immune protection. Viral mutations that escape from CTL recognition have been previously described in humans infected with human immunodeficiency virus (HIV) and monkeys infected with simian immunodeficiency virus (SIV). In a cohort of rhesus monkeys that were vaccinated and subsequently infected with a pathogenic hybrid simian-human immunodeficiency virus (SHIV), the frequency of viral sequence mutations within CTL epitopes correlated with the level of viral replication. A single nucleotide mutation within an immunodominant Gag CTL epitope in an animal with undetectable plasma viral RNA resulted in viral escape from CTLs, a burst of viral replication, clinical disease progression, and death from AIDS-related complications. These data indicate that viral escape from CTL recognition may be a major limitation of the CTL-based AIDS vaccines that are likely to be administered to large human populations over the next several years.
Asunto(s)
Vacunas contra el SIDA/inmunología , Síndrome de Inmunodeficiencia Adquirida/inmunología , Vacunas contra el SIDAS/inmunología , Síndrome de Inmunodeficiencia Adquirida del Simio/inmunología , Linfocitos T Citotóxicos/inmunología , Vacunas contra el SIDA/genética , Sustitución de Aminoácidos , Animales , Linfocitos T CD8-positivos/inmunología , Análisis Mutacional de ADN , Epítopos de Linfocito T/genética , Epítopos de Linfocito T/inmunología , Genes gag , VIH-1/genética , VIH-1/inmunología , Humanos , Inmunidad , Depleción Linfocítica , Macaca mulatta , Mutación , Virus de la Inmunodeficiencia de los Simios/genética , Virus de la Inmunodeficiencia de los Simios/inmunología , Vacunas Sintéticas/inmunología , Replicación ViralRESUMEN
High levels of infused anti-human immunodeficiency virus type 1 (HIV-1) neutralizing monoclonal antibodies (MAbs) can completely protect macaque monkeys against mucosal chimeric simian-human immunodeficiency virus (SHIV) infection. Antibody levels below the protective threshold do not prevent infection but can substantially reduce plasma viremia. To assess if HIV-1/SIV-specific cellular immunity could combine with antibodies to produce sterile protection, we studied the effect of a suboptimal infusion of anti-HIV-1 neutralizing antibodies in macaques with active cellular immunity induced by interleukin-2 (IL-2)-adjuvanted DNA immunization. Twenty female macaques were divided into four groups: (i). DNA immunization plus irrelevant antibody, (ii). DNA immunization plus infusion of neutralizing MAbs 2F5 and 2G12, (iii). sham DNA plus 2F5 and 2G12, and (iv). sham DNA plus irrelevant antibody. DNA-immunized monkeys developed CD4 and CD8 T-cell responses as measured by epitope-specific tetramer staining and by pooled peptide ELISPOT assays for gamma interferon-secreting cells. After vaginal challenge, DNA-immunized animals that received irrelevant antibody became SHIV infected but displayed lower plasma viremia than control animals. Complete protection against SHIV challenge occurred in three animals that received sham DNA plus MAbs 2F5 and 2G12 and in two animals that received the DNA vaccine plus MAbs 2F5 and 2G12. Thus, although DNA immunization produced robust HIV-specific T-cell responses, we were unable to demonstrate that these responses contributed to the sterile protection mediated by passive infusion of neutralizing antibodies. These data suggest that although effector T cells can limit viral replication, they are not able to assist humoral immunity to prevent the establishment of initial infection.
Asunto(s)
VIH-1/inmunología , Inmunización Pasiva , Vacunas contra el SIDAS/inmunología , Síndrome de Inmunodeficiencia Adquirida del Simio/prevención & control , Linfocitos T/inmunología , Vacunas de ADN/inmunología , Animales , Anticuerpos Antivirales/sangre , Recuento de Linfocito CD4 , Femenino , Humanos , Inmunidad Celular , Interleucina-2/farmacología , Macaca mulatta , Pruebas de Neutralización , Virus de la Inmunodeficiencia de los Simios/inmunología , Vacunación , Vagina/virologíaRESUMEN
Although a consensus has emerged that an HIV vaccine should elicit a cytotoxic T lymphocyte (CTL) response, the characteristics of an effective vaccine-induced T lymphocyte response remain unclear. We explored this issue in the simian human immunodeficiency virus/rhesus monkey model in the course of assessing the relative immunogenicity of vaccine regimens that included a cytokine-augmented plasmid DNA prime and a boost with DNA or recombinant pox vectors. Recombinant vaccinia virus, recombinant modified vaccinia Ankara (MVA), and recombinant fowlpox were comparable in their immunogenicity. Moreover, whereas the magnitude of the peak vaccine-elicited T lymphocyte responses in the recombinant pox virus-boosted monkeys was substantially greater than that seen in the monkeys immunized with plasmid DNA alone, the magnitudes of recombinant pox boosted CTL responses decayed rapidly and were comparable to those of the DNA-alone-vaccinated monkeys by the time of viral challenge. Consistent with these comparable memory T cell responses, the clinical protection seen in all groups of experimentally vaccinated monkeys was similar. This study, therefore, indicates that the steady-state memory, rather than the peak effector vaccine-elicited T lymphocyte responses, may be the critical immune correlate of protection for a CTL-based HIV vaccine.
Asunto(s)
Memoria Inmunológica , Poxviridae/genética , Linfocitos T Citotóxicos/inmunología , Linfocitos T/inmunología , Animales , Recuento de Linfocito CD4 , Linfocitos T CD8-positivos/inmunología , Ensayo de Inmunoadsorción Enzimática , Recuento de Linfocitos , Macaca mulatta , Reacción en Cadena de la Polimerasa/métodos , ARN Viral/inmunología , Mapeo Restrictivo , Virus Vaccinia/genética , Vacunas Virales/inmunologíaRESUMEN
Virus-specific cytotoxic T lymphocytes (CTL) are critical for control of human immunodeficiency virus type 1 replication. However, viral escape from CTL recognition can undermine this immune control. Here we demonstrate the high frequency and pattern of viral escape from dominant epitope-specific CTL in SIV gag DNA-vaccinated rhesus monkeys following a heterologous simian immunodeficiency virus (SIV) challenge. DNA-vaccinated monkeys exhibited initial effective control of the SIV challenge, but this early control was lost by serial breakthroughs of viral replication over a 3-year follow-up period. Increases in plasma viral RNA correlated temporally with declines of dominant SIV epitope-specific CD8(+) T-lymphocyte responses and the emergence of viral mutations that escaped recognition by dominant epitope-specific CTL. Viral escape from CTL occurred in a total of seven of nine vaccinated and control monkeys, including three animals that initially controlled viral replication to undetectable levels of plasma viral RNA. These data suggest that CTL exert selective pressure on viral replication and that viral escape from CTL may be a limitation of CTL-based AIDS vaccine strategies.
Asunto(s)
Epítopos Inmunodominantes/inmunología , Virus de la Inmunodeficiencia de los Simios/inmunología , Linfocitos T Citotóxicos/inmunología , Vacunas de ADN/inmunología , Vacunas Virales/inmunología , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Cartilla de ADN , Evolución Molecular , Epítopos Inmunodominantes/química , Macaca mulatta , Virus de la Inmunodeficiencia de los Simios/genéticaRESUMEN
Recent studies of human immunodeficiency virus type 1 (HIV-1) infection in humans and of simian immunodeficiency virus (SIV) in rhesus monkeys have shown that resolution of the acute viral infection and control of the subsequent persistent infection are mediated by the antiviral cellular immune response. We comparatively assessed several vaccine vector delivery systems-three formulations of a plasmid DNA vector, the modified vaccinia Ankara (MVA) virus, and a replication incompetent adenovirus type 5 (Ad5) vector-expressing the SIV gag protein for their ability to elicit such immune responses in monkeys. The vaccines were tested either as a single modality or in combined modality regimens. Here we show that the most effective responses were elicited by a replication-incompetent Ad5 vector, used either alone or as a booster inoculation after priming with a DNA vector. After challenge with a pathogenic HIV-SIV hybrid virus (SHIV), the animals immunized with Ad5 vector exhibited the most pronounced attenuation of the virus infection. The replication-defective adenovirus is a promising vaccine vector for development of an HIV-1 vaccine.