Matthews Rebecca L, Khan Nazneen, Beckman Bradley, Sharma Simran, Dietz Zackary, Picking William D, Izmirlian Grant, Sanders Chelsea, Stocks Stacy M, Difilippantonio Simone, Kirnbauer Reinhard, Roden Richard B, Pinto Ligia A, Shoemaker Robert H, Ernst Robert K, Marshall Jason D
Cancer ImmunoPrevention Laboratory, Frederick National Laboratory for Cancer Research, Frederick, MD, USA.
Department of Veterinary Pathobiology and Bond Life Sciences Center, University of Missouri, Columbia, MO, USA.
Vaccine. 2025 Jan 12;44:126577. doi: 10.1016/j.vaccine.2024.126577. Epub 2024 Dec 3.
The TLR4 (Toll-like receptor 4)-activating agonist MPLA (monophosphoryl lipid A) is a key component of the adjuvant systems AS01 and AS04, utilized in marketed preventive vaccines for several infectious pathogens. As MPLA is a biologically-derived product containing a mixture of several lipid A congeners with a 4' phosphoryl group and varying numbers of acyl chains with distinct activities, extensive efforts to refine its production and immunogenicity are ongoing; notably, the development of the BECC (Bacterial Enzymatic Combinatorial Chemistry) system in which bacteria express lipid A-modifying enzymes to produce a panoply of lipid A congeners. In an effort to characterize the adjuvant activity of these lipid A congeners, we compared biologically-derived and synthetic versions of BECC470 and BECC438 for adjuvant activity in BALB/c mice vaccinated with the HPV (Human papilloma virus) VLP-based vaccine, RG1-VLP. Synthetic BECC compounds compared favorably to biological versions and, in the case of synthetic BECC470, were routinely superior to their biologically-derived BECC counterpart. Synthetic BECC470-adjuvanted vaccines achieved broad spectrum immune activity characterized by elevated levels of total IgG and IgG2a subtype specific to HPV16 L1 VLPs and the HPV16 L2 peptide, as well as robust HPV16-neutralizing antibody titers. In addition, synthetic BECC470 promoted strong T cell responses to HPV16 L1, increased memory B cell frequency, and increased the T follicular helper cell (Tfh) population in draining lymph nodes. In contrast, the biologically-derived form of BECC470 induced an immune profile specific for highest levels of HPV16 L2-specific IgG2a as well as antibodies cross-neutralizing to HPV18 and HPV39. These data confirm that a synthetically-derived BECC compound can be combined with Alhydrogel to adjuvant the RG1-VLP vaccine as can biologically-derived BECC compounds and MPLA, albeit with subtly distinct immune responses. The distinctions in immune profiles triggered by these BECC compounds warrant further exploration for their capacity to activate TLR4 and modulate immune responses to vaccines.
Toll样受体4（TLR4）激活激动剂单磷酰脂质A（MPLA）是佐剂系统AS01和AS04的关键成分，用于多种传染病原体的上市预防性疫苗。由于MPLA是一种生物衍生产品，包含几种具有4'磷酸基团的脂质A同系物混合物以及数量不同、活性各异的酰基链，因此正在进行大量工作来优化其生产和免疫原性；值得注意的是，细菌表达脂质A修饰酶以产生一系列脂质A同系物的细菌酶促组合化学（BECC）系统的开发。为了表征这些脂质A同系物的佐剂活性，我们比较了生物衍生型和合成型BECC470和BECC438在接种基于人乳头瘤病毒（HPV）病毒样颗粒（VLP）的RG1-VLP疫苗的BALB/c小鼠中的佐剂活性。合成的BECC化合物与生物型相比表现良好，就合成型BECC470而言，通常优于其生物衍生的BECC对应物。合成BECC470佐剂疫苗实现了广谱免疫活性，其特征是针对HPV16 L1 VLP和HPV16 L2肽的总IgG和IgG2a亚型水平升高，以及强大的HPV16中和抗体滴度。此外，合成BECC470促进了对HPV16 L1的强烈T细胞反应，增加了记忆B细胞频率，并增加了引流淋巴结中的滤泡辅助性T细胞（Tfh）群体。相比之下，生物衍生型BECC470诱导了一种免疫谱，其特征是HPV16 L2特异性IgG2a水平最高以及对HPV18和HPV39的交叉中和抗体。这些数据证实，合成衍生的BECC化合物可以与氢氧化铝佐剂用于RG1-VLP疫苗，生物衍生的BECC化合物和MPLA也可以，尽管免疫反应略有不同。这些BECC化合物引发的免疫谱差异值得进一步探索它们激活TLR4和调节疫苗免疫反应的能力。
