Crofts Kali F, Page Courtney L, Swedik Stephanie M, Holbrook Beth C, Meyers Allison K, Zhu Xuewei, Parsonage Derek, Westcott Marlena M, Alexander-Miller Martha A
Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC 27101, USA.
Department of Internal Medicine, Section on Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27101, USA.
Vaccines (Basel). 2023 Jul 20;11(7):1261. doi: 10.3390/vaccines11071261.
Subunit or inactivated vaccines comprise the majority of vaccines used against viral and bacterial pathogens. However, compared to their live/attenuated counterparts, these vaccines often demonstrate reduced immunogenicity, requiring multiple boosters and or adjuvants to elicit protective immune responses. For this reason, studies of adjuvants and the mechanism through which they can improve inactivated vaccine responses are critical for the development of vaccines with increased efficacy. Studies have shown that the direct conjugation of adjuvant to antigen promotes vaccine immunogenicity, with the advantage of both the adjuvant and antigen targeting the same cell. Using this strategy of direct linkage, we developed an inactivated influenza A (IAV) vaccine that is directly conjugated with the Toll-like receptor 7/8 agonist resiquimod (R848) through a heterobifunctional crosslinker. Previously, we showed that this vaccine resulted in improved protection and viral clearance in newborn nonhuman primates compared to a non-adjuvanted vaccine. We subsequently discovered that the choice of linker used to conjugate R848 to the virus alters the stimulatory activity of the vaccine, promoting increased maturation and proinflammatory cytokine production from DC differentiated in vitro. With this knowledge, we explored how the choice of crosslinker impacts the stimulatory activity of these vaccines. We found that the linker choice alters signaling through the NF-κB pathway in human monocyte-derived dendritic cells (moDCs). Further, we extended our analyses to in vivo differentiated APC present in human peripheral blood, replicating the linker-dependent differences found in in vitro differentiated cells. Finally, we demonstrated in a mouse model that the choice of linker impacts the amount of IAV-specific IgG antibody produced in response to vaccination. These data enhance our understanding of conjugation approaches for improving vaccine immunogenicity.
亚单位疫苗或灭活疫苗占用于对抗病毒和细菌病原体的疫苗的大部分。然而，与它们的活疫苗/减毒疫苗对应物相比，这些疫苗通常表现出免疫原性降低，需要多次加强免疫和/或佐剂来引发保护性免疫反应。因此，对佐剂及其改善灭活疫苗反应机制的研究对于开发高效疫苗至关重要。研究表明，佐剂与抗原的直接偶联可促进疫苗的免疫原性，其优点是佐剂和抗原靶向同一细胞。利用这种直接连接策略，我们开发了一种灭活甲型流感病毒（IAV）疫苗，该疫苗通过异双功能交联剂与Toll样受体7/8激动剂瑞喹莫德（R848）直接偶联。此前，我们表明，与无佐剂疫苗相比，这种疫苗在新生非人灵长类动物中产生了更好的保护作用和病毒清除效果。随后，我们发现用于将R848与病毒偶联的连接子的选择会改变疫苗的刺激活性，促进体外分化的树突状细胞（DC）的成熟增加和促炎细胞因子的产生。基于这一认识，我们探讨了交联剂的选择如何影响这些疫苗的刺激活性。我们发现连接子的选择会改变人单核细胞衍生树突状细胞（moDCs）中通过NF-κB途径的信号传导。此外，我们将分析扩展到存在于人类外周血中的体内分化的抗原呈递细胞（APC），重现了在体外分化细胞中发现的连接子依赖性差异。最后，我们在小鼠模型中证明，连接子的选择会影响接种疫苗后产生的IAV特异性IgG抗体的量。这些数据加深了我们对改善疫苗免疫原性的偶联方法的理解。
