Londoño Andrés F, Sharma Ajay, Sealy Jared, Rana Vipin S, Foor Shelby D, Matrosova Vera Y, Gaidamakova Elena K, Volpe Robert P, Daly Michael J, Hoffman Brian M, Pal Utpal, Dumler J Stephen
School of Medicine, Department of Pathology, Uniformed Services University of the Health Sciences (USUHS), Bethesda, Maryland, USA.
Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, USA.
mBio. 2025 Feb 5;16(2):e0313124. doi: 10.1128/mbio.03131-24. Epub 2024 Dec 27.
The bacterium responsible for Lyme disease, , accumulates high levels of manganese without iron and possesses a polyploid genome, characteristics suggesting potential extreme resistance to radiation. Contrary to expectations, we report that wild-type B31 cells are radiosensitive, with a gamma-radiation survival limit for 10 wild-type cells of <1 kGy. Thus, we explored radiosensitivity through electron paramagnetic resonance (EPR) spectroscopy by quantitating the fraction of Mn present as antioxidant Mn metabolite complexes (H-Mn). The spirochetes displayed relatively low levels of H-Mn, in stark contrast to the extremely radiation-resistant . The H-Mn content as revealed by EPR spectroscopy is sufficiently sensitive to detect small changes in radiosensitivity among strains. However, cells are significantly more sensitive than predicted by EPR, implicating their linear genome architecture as an additional explanation for radiosensitivity. We then explored the influence of the Mn-decapeptide-phosphate antioxidant complex MDP, known to shield proteins during irradiation, and showed that treatment with MDP preserves epitopes at 5 kGy irradiation, which crucially prevents cell proliferation. This finding defines some of the pivotal mechanisms that evolved to survive oxidative conditions experienced with tick and mammal immune responses. These observations also provide an opportunity for innovative vaccine development strategies employing ionizing radiation to disrupt the genome, while maintaining antigenic potency. These fresh insights extend our understanding of the unique biology of and open new avenues for considering novel whole-cell Lyme disease vaccines using MDP and irradiation-based inactivation.IMPORTANCEThe study highlights that electron paramagnetic resonance (EPR) spectroscopy is sufficiently sensitive to detect small differences in radiation resistance among strains based on their population of Mn-metabolite complexes (H-Mn). appears to have evolved a system not to protect from irradiation, but presumably to protect from oxidative stress when cyclically transmitted from tick to mammalian host and back. These data also suggest a path forward in the development of novel vaccines against spirochete infections, including Lyme disease, through preparation involving the synthetic Mn-decapeptide-phosphate antioxidant complex MDP to provide epitope protection during sterilizing gamma-irradiation that eliminates growth. Given the current lack of effective whole-cell vaccines for Lyme disease, this research identifies a potential strategy for developing alternative radiation-inactivated, yet highly effective vaccines.
引发莱姆病的细菌，……，在无铁的情况下积累高水平的锰，并拥有多倍体基因组，这些特征表明其可能对辐射具有极强的抗性。与预期相反，我们报告野生型B31细胞对辐射敏感，10个野生型细胞的γ辐射存活极限<1千戈瑞。因此，我们通过电子顺磁共振（EPR）光谱法，通过定量作为抗氧化剂锰代谢物复合物（H-Mn）存在的锰的比例来探究辐射敏感性。与极具辐射抗性的……相比，这些螺旋体显示出相对较低水平的H-Mn。EPR光谱揭示的H-Mn含量足够灵敏，能够检测不同……菌株之间辐射敏感性的微小变化。然而，……细胞比EPR预测的要敏感得多，这表明它们的线性基因组结构是辐射敏感性的另一个解释。然后，我们探究了已知在辐射期间能保护蛋白质的锰十肽 - 磷酸盐抗氧化剂复合物MDP的影响，并表明用MDP处理可在5千戈瑞辐射下保留……表位，这至关重要地阻止了细胞增殖。这一发现定义了……为在蜱和哺乳动物免疫反应所经历的氧化条件下存活而进化出的一些关键机制。这些观察结果也为创新疫苗开发策略提供了机会，该策略利用电离辐射破坏……基因组，同时保持抗原效力。这些新见解扩展了我们对……独特生物学的理解，并为考虑使用MDP和基于辐射的灭活方法开发新型全细胞莱姆病疫苗开辟了新途径。
重要性
该研究强调，电子顺磁共振（EPR）光谱足够灵敏，能够根据其锰代谢物复合物（H-Mn）的数量检测不同……菌株之间辐射抗性的微小差异。……似乎进化出了一种系统，不是为了抵御辐射，而是大概为了在从蜱到哺乳动物宿主再返回的循环传播过程中抵御氧化应激。这些数据还为开发针对螺旋体感染（包括莱姆病）的新型疫苗指明了一条前进的道路，该疫苗制备涉及合成锰十肽 - 磷酸盐抗氧化剂复合物MDP，以在消除生长的杀菌γ辐射期间提供……表位保护。鉴于目前缺乏有效的莱姆病全细胞疫苗，这项研究确定了一种开发替代辐射灭活但高效疫苗的潜在策略。
