Accelerator Radioisotope Research Section, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea.
Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
Microbiol Spectr. 2023 Aug 17;11(4):e0135823. doi: 10.1128/spectrum.01358-23. Epub 2023 Jun 5.
Respiratory syncytial virus (RSV) is a common respiratory pathogen that causes lower respiratory diseases among infants and elderly people. Moreover, formalin-inactivated RSV (FI-RSV) vaccine induces serious enhanced respiratory disease (ERD). Radiation has been investigated as an alternative approach for producing inactivated or live-attenuated vaccines, which enhance the antigenicity and heterogeneous protective effects of vaccines compared with conventional formalin inactivation. In this study, we developed an RSV vaccine using gamma irradiation and analyzed its efficacy against RSV vaccine-induced ERD in a mouse model. Although gamma irradiation-inactivated RSV (RI-RSV) carbonylation was lower than FI-RSV carbonylation and RI-RSV showed a significant antibody production and viral clearance, RI-RSV caused more obvious body weight loss, pulmonary eosinophil infiltration, and pulmonary mucus secretion. Further, the conversion of prefusion F (pre-F) to postfusion F (post-F) was significant for both RI-RSV and FI-RSV, while that of RI-RSV was significantly higher than that of FI-RSV. We found that the conversion from pre- to post-F during radiation was caused by radiation-induced reactive oxygen species. Although we could not propose an effective RSV vaccine manufacturing method, we found that ERD was induced by RSV vaccine by various biochemical effects that affect antigen modification during RSV vaccine manufacturing, rather than simply by the combination of formalin and alum. Therefore, these biochemical actions should be considered in future developments of RSV vaccine. Radiation inactivation for viral vaccine production has been known to elicit a better immune response than other inactivation methods due to less surface protein damage. However, we found in this study that radiation-inactivated RSV (RI-RSV) vaccine induced a level of immune response similar to that induced by formalin-inactivated RSV (FI-RSV). Although RI-RSV vaccine showed less carbonylation than FI-RSV, it induced more conformational changes from pre-F to post-F due to the gamma radiation-induced reactive oxygen species response, which may be a key factor in RI-RSV-induced ERD. Therefore, ERD induced by RSV vaccine may be due to pre-F to post-F denaturation by random protein modifications caused by external stress. Our findings provide new ideas for inactivated vaccines for RSV and other viruses and confirm the importance of pre-F in RSV vaccines.
呼吸道合胞病毒（RSV）是一种常见的呼吸道病原体，可导致婴儿和老年人下呼吸道疾病。此外，福尔马林灭活的 RSV（FI-RSV）疫苗会引起严重的增强性呼吸道疾病（ERD）。辐照已被研究作为生产灭活或减毒活疫苗的替代方法，与传统的福尔马林灭活相比，这种方法增强了疫苗的抗原性和异源保护效果。在这项研究中，我们使用伽马辐照开发了一种 RSV 疫苗，并分析了其在小鼠模型中对 RSV 疫苗诱导的 ERD 的疗效。虽然伽马辐照灭活的 RSV（RI-RSV）的羰基化程度低于 FI-RSV 的羰基化程度，并且 RI-RSV 表现出显著的抗体产生和病毒清除，但 RI-RSV 导致更明显的体重减轻、肺嗜酸性粒细胞浸润和肺粘液分泌。此外，RI-RSV 和 FI-RSV 的前融合 F（pre-F）到后融合 F（post-F）的转化都很显著，而 RI-RSV 的转化明显高于 FI-RSV。我们发现，辐照过程中 pre-F 到 post-F 的转化是由辐照诱导的活性氧引起的。虽然我们不能提出一种有效的 RSV 疫苗制造方法，但我们发现 ERD 是由 RSV 疫苗通过影响 RSV 疫苗制造过程中抗原修饰的各种生化作用引起的，而不仅仅是福尔马林和明矾的结合。因此，在未来 RSV 疫苗的开发中应考虑这些生化作用。
用于病毒疫苗生产的辐射灭活已被证明比其他灭活方法产生更好的免疫反应，因为它对表面蛋白的损伤较小。然而，我们在这项研究中发现，辐照灭活的 RSV（RI-RSV）疫苗引起的免疫反应水平与福尔马林灭活的 RSV（FI-RSV）疫苗相似。尽管 RI-RSV 疫苗的羰基化程度低于 FI-RSV，但由于伽马辐射诱导的活性氧反应，它引起了更多的 pre-F 到 post-F 的构象变化，这可能是 RI-RSV 诱导的 ERD 的关键因素。因此，RSV 疫苗引起的 ERD 可能是由于外部应激引起的随机蛋白修饰导致 pre-F 到 post-F 的变性。我们的研究结果为 RSV 和其他病毒的灭活疫苗提供了新的思路，并证实了 pre-F 在 RSV 疫苗中的重要性。
