Goulart Cibelly, Rodriguez Dunia, Kanno Alex I, Lu Ying-Jie, Malley Richard, Leite Luciana C C
Centro de Biotecnologia, Instituto Butantan, Brazil; Programa De Pós-Graduação Interunidades em Biotecnologia USP-I.Butantan-IPT, Brazil.
Centro de Biotecnologia, Instituto Butantan, Brazil.
Vaccine. 2017 Mar 23;35(13):1683-1691. doi: 10.1016/j.vaccine.2017.02.029. Epub 2017 Feb 24.
Pneumococcal proteins have been evaluated as genetically-conserved potential vaccine candidates. We have previously demonstrated that a fragment of PspA in fusion with PdT (rPspA-PdT) induced protective immune responses in mice. However, purified proteins have shown poor immunogenicity and often require the combination with strong adjuvants and booster doses. Here, we investigated the use of a Bacillus Calmette-Guérin (BCG) strain, a well-established prophylactic vaccine for tuberculosis with known adjuvant properties, for delivery of the PspA-PdT fusion protein. Immunization of mice in a prime-boost strategy, using rPspA-PdT as a boost, demonstrated that rBCG PspA-PdT/rPspA-PdT was able to induce an antibody response against both proteins, promoting an IgG1 to IgG2 antibody isotype shift. Sera from rBCG PspA-PdT/rPspA-PdT immunized mice showed antibodies able to bind to the pneumococcal surface and promoted higher complement deposition when compared with WT-BCG/rPspA-PdT or a single dose of rPspA-PdT. In addition, these antisera inhibited the cytolytic activity of Ply. Production of interleukin-6 (IL-6), gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α) was increased in splenocytes culture. Furthermore, a higher expression of CD69 early activation molecule was observed on splenic CD4 T cells from mice immunized with rBCG PspA-PdT before and after the protein booster dose. Finally, immunization with rBCG PspA-PdT/rPspA-PdT protected mice against pneumococcal lethal challenge. These results support the further investigation of recombinant BCG strains to express pneumococcal proteins, which could be administered in early stages of life and lead to protective pneumococcal immunity in infants and children.
肺炎球菌蛋白已被评估为具有遗传保守性的潜在疫苗候选物。我们之前已经证明，与PdT融合的PspA片段（rPspA-PdT）在小鼠中诱导了保护性免疫反应。然而，纯化的蛋白显示出较差的免疫原性，并且通常需要与强效佐剂和加强剂量联合使用。在此，我们研究了使用卡介苗（BCG）菌株，一种用于结核病的成熟预防性疫苗，已知具有佐剂特性，来递送PspA-PdT融合蛋白。采用rPspA-PdT作为加强剂，以初免-加强策略免疫小鼠，结果表明rBCG PspA-PdT/rPspA-PdT能够诱导针对两种蛋白的抗体反应，促进IgG1向IgG2抗体亚型的转变。与WT-BCG/rPspA-PdT或单剂量rPspA-PdT相比，rBCG PspA-PdT/rPspA-PdT免疫小鼠的血清显示出能够结合肺炎球菌表面的抗体，并促进更高的补体沉积。此外，这些抗血清抑制了Ply的细胞溶解活性。脾细胞培养中白细胞介素-6（IL-6）、γ干扰素（IFN-γ）和肿瘤坏死因子α（TNF-α）的产生增加。此外，在用蛋白加强剂量之前和之后，用rBCG PspA-PdT免疫的小鼠脾脏CD4 T细胞上观察到CD69早期激活分子的表达更高。最后，用rBCG PspA-PdT/rPspA-PdT免疫可保护小鼠免受肺炎球菌致死性攻击。这些结果支持进一步研究表达肺炎球菌蛋白的重组BCG菌株，其可在生命早期给药，并在婴幼儿中产生保护性肺炎球菌免疫力。
