RESUMO
Venezuelan equine encephalitis virus replicon particles (VRP) were engineered to express different forms of SIV Gag to compare expression in vitro, formation of intra- and extracellular structures and induction of humoral and cellular immunity in mice. The three forms examined were full-length myristylated SIV Gag (Gagmyr+), full-length Gag lacking the myristylation signal (Gagmyr-) or a truncated form of Gagmyr- comprising only the matrix and capsid domains (MA/CA). Comparison of VRP-infected primary mouse embryo fibroblasts, mouse L929 cells and primate Vero cells showed comparable expression levels for each protein, as well as extracellular virus-like particles (VRP-Gagmyr+) and distinctive cytoplasmic aggregates (VRP-Gagmyr-) with each cell type. VRP were used to immunize BALB/c mice, and immune responses were compared using an interferon (IFN)-gamma ELISPOT assay and a serum antibody ELISA. Although all three VRP generated similar levels of IFN-gamma-producing cells at 1 week post-boost, at 10 weeks post-boost the MA/CA-VRP-induced response was maintained at a significantly higher level relative to that induced by Gagmyr+-VRP. Antibody responses to MA/CA-VRP and Gagmyr+-VRP were not significantly different.
Assuntos
Vírus da Encefalite Equina Venezuelana/genética , Produtos do Gene gag/imunologia , Vetores Genéticos/genética , Vírus da Imunodeficiência Símia/imunologia , Vacinas Virais/imunologia , Animais , Anticorpos Antivirais/sangue , Linhagem Celular , Células Cultivadas , Chlorocebus aethiops , Embrião de Mamíferos/citologia , Ensaio de Imunoadsorção Enzimática , Feminino , Fibroblastos , Produtos do Gene gag/química , Antígenos H-2/imunologia , Interferon gama/biossíntese , Linfócitos/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos , Microscopia Eletrônica de Transmissão , Modelos Animais , Gravidez , Replicon/genética , Vacinas Sintéticas/genética , Vacinas Sintéticas/imunologia , Células Vero , Vacinas Virais/genéticaRESUMO
VEE replicon particles (VRP), non-propagating vaccine vectors derived from Venezuelan equine encephalitis virus (VEE), were engineered to express immunogens from the cloned isolate SIVsmH-4, combined in a vaccine cocktail and inoculated subcutaneously to immunize rhesus macaques. The virulent, uncloned challenge stock, SIVsmE660, represented a type of heterologous challenge and the intrarectal challenge modeled infection across a mucosal surface. Prechallenge neutralizing antibodies against SIVsmH-4 were induced in all vaccinates, and a prechallenge cellular immune response could be detected in one of six. Post-challenge, virus loads were reduced at the peak, at set point and at termination (41 weeks post-challenge), although these differences did not reach statistical significance. Significantly elevated levels of CD4+ T cells were observed post-challenge. A strong correlation was noted between a net increase in CD4+ T cell count and lowered virus load at set point.