RESUMEN
Growing concerns about unpredictable influenza pandemics require a broadly protective vaccine against diverse influenza strains. One of the promising approaches was a T cell-based vaccine, but the narrow breadth of T-cell immunity due to the immunodominance hierarchy established by previous influenza infection and efficacy against only mild challenge condition are important hurdles to overcome. To model T-cell immunodominance hierarchy in humans in an experimental setting, influenza-primed C57BL/6 mice were chosen and boosted with a mixture of vaccinia recombinants, individually expressing consensus sequences from avian, swine, and human isolates of influenza internal proteins. As determined by IFN-γ ELISPOT and polyfunctional cytokine secretion, the vaccinia recombinants of influenza expanded the breadth of T-cell responses to include subdominant and even minor epitopes. Vaccine groups were successfully protected against 100 LD50 challenges with PR/8/34 and highly pathogenic avian influenza H5N1, which contained the identical dominant NP366 epitope. Interestingly, in challenge with pandemic A/Cal/04/2009 containing mutations in the dominant epitope, only the group vaccinated with rVV-NP + PA showed improved protection. Taken together, a vaccinia-based influenza vaccine expressing conserved internal proteins improved the breadth of influenza-specific T-cell immunity and provided heterosubtypic protection against immunologically close as well as distant influenza strains.
Asunto(s)
Vacunas contra la Influenza/inmunología , Vacunas contra la Influenza/farmacología , Gripe Humana/prevención & control , Virus Vaccinia/inmunología , Animales , Modelos Animales de Enfermedad , Femenino , Humanos , Subtipo H1N1 del Virus de la Influenza A/inmunología , Subtipo H5N1 del Virus de la Influenza A/inmunología , Gripe Humana/inmunología , Ratones , Ratones Endogámicos C57BL , Infecciones por Orthomyxoviridae/inmunología , Infecciones por Orthomyxoviridae/prevención & control , Porcinos , Linfocitos T/inmunología , Vaccinia/inmunologíaRESUMEN
A neutralizing epitope fragment of ApxIIA toxin (ApxIIA#5) of the Korean Actinobacillus pleuropneumoniae serotype 2 strain was expressed and immobilized on the cell surface of Saccharomyces cerevisiae for efficient vaccine development. Expression of ApxIIA#5 was confirmed by Western blot analysis using cell-wall proteins, and the surface display of ApxIIA#5 was further visualized under confocal microscopy. Quantitative ELISA revealed that the recombinant ApxIIA#5 directed to the cell surface consisted of approximately 16% cell-wall proteins, estimated to be 35 mg of ApxIIA#5 protein per liter of cultured cells. An immunoassay revealed that antigen-specific antibodies against ApxIIA#5 were present in the sera of mice fed recombinant ApxIIA#5-expressing yeast, but not in mice fed the wild-type nor the vector-only transformant. Moreover, the mice fed the recombinant epitope-expressing yeast were protected from injection of a lethal dose of A. pleuropneumoniae.