Alfini Renzo, Brunelli Brunella, Bartolini Erika, Carducci Martina, Luzzi Enrico, Ferlicca Francesca, Buccato Scilla, Galli Barbara, Lo Surdo Paola, Scarselli Maria, Romagnoli Giacomo, Cartocci Elena, Maione Domenico, Savino Silvana, Necchi Francesca, Delany Isabel, Micoli Francesca
GSK Vaccines Institute for Global Health (GVGH), 53100 Siena, Italy.
GSK, 53100 Siena, Italy.
Vaccines (Basel). 2022 Jul 26;10(8):1182. doi: 10.3390/vaccines10081182.
GMMA are outer membrane vesicles (OMVs) released from Gram-negative bacteria genetically modified to enhance OMVs formation that have been shown to be optimal systems to enhance immunogenicity of protein antigens. Here, we selected factor H binding protein (fHbp) and used the conjugation chemistry as a tool to alter antigen orientation on GMMA. Indeed, fHbp was randomly linked to GMMA or selectively attached via the N-terminus to mimic native presentation of the protein on the bacterial surface. Interestingly, protein and peptide array analyses confirmed that antibodies induced by the selective and the random conjugates showed a pattern very similar to fHbp natively expressed on bacterial surfaces or to the recombinant protein mixed with GMMA, respectively. However, the two conjugates elicited antibodies with similar serum bactericidal activity against meningococcal strains, superior to the protein alone or physically mixed with GMMA. Presentation of fHbp on GMMA strongly enhances the functional immune response elicited by the protein but its orientation on the bacterial surface does not have an impact. This study demonstrates the flexibility of the GMMA platform as a display and delivery system for enhancing antigen immunogenicity and further supports the use of such promising technology for the development of effective vaccines.
基因修饰的多聚麦芽糖醛酸（GMMA）是革兰氏阴性菌释放的外膜囊泡（OMV），经基因改造以增强OMV的形成，已被证明是增强蛋白质抗原免疫原性的最佳系统。在此，我们选择了H因子结合蛋白（fHbp），并使用共轭化学作为工具来改变GMMA上抗原的方向。事实上，fHbp随机连接到GMMA上，或通过N端选择性连接，以模拟该蛋白在细菌表面的天然呈现。有趣的是，蛋白质和肽阵列分析证实，由选择性和随机共轭物诱导的抗体分别显示出与细菌表面天然表达的fHbp或与GMMA物理混合的重组蛋白非常相似的模式。然而，这两种共轭物诱导产生的抗体对脑膜炎球菌菌株具有相似的血清杀菌活性，优于单独的蛋白质或与GMMA物理混合的蛋白质。fHbp在GMMA上的呈现强烈增强了该蛋白引发的功能性免疫反应，但其在细菌表面的方向并无影响。这项研究证明了GMMA平台作为增强抗原免疫原性的展示和递送系统的灵活性，并进一步支持将这种有前景的技术用于开发有效的疫苗。
