Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infections in children. Inactivated RSV vaccine was developed in the late 1960’s, but the vaccine-enhanced disease (VED) occurred to vaccinated infants upon subsequent natural RSV infection. The excessive inflammatory immunopathology in the lungs might be involved in the VED, but the underlying mechanisms remain not fully understood. In this study, we utilized UV-inactivated RSV in the prime/boost approach followed by RSV challenge in BALB/c mice to mimic RSV VED. The dynamic virus load, cytokines, histology and transcriptome profiles in lung tissues of mice were investigated from day 1 to day 6 post-infection. Compared to PBS-treated mice, UV-RSV vaccination leads to a Th2 type inflammatory response characterized by enhanced histopathology, reduced Treg cells and increased IL4⁺CD4 T cells in the lung. Enhanced production of several Th2 type cytokines (IL-4, IL-5, IL-10) and TGF-β), reduction of IL-6 and IL-17 were observed in UV-RSV vaccinated mice. A total of 5582 differentially expressed (DE) genes between PBS-treated or vaccinated mice and naïve mice were identified by RNA-Seq. Eleven conserved high-influential modules (HMs) were recognized, majorly grouped into regulatory networks related to cell cycle and cell metabolism, signal transduction, immune and inflammatory responses. At an early time post-infection, the vaccinated mice showed obvious decreased expression patterns of DE genes in 11 HMs compared to PBS-treated mice. The extracellular matrix (HM5) and immune responses (HM8) revealed tremendous differences in expression and regulation characteristics of transcripts between PBS-treated and vaccinated mice at both early and late time points. The highly connected genes in HM5 and HM8 networks were further validated by RT-qPCR. These findings reveal the relationship between RSV VED and immune responses, which could benefit the development of novel RSV vaccines.

呼吸道合胞病毒（RSV）是儿童下呼吸道感染的主要原因。灭活 RSV 疫苗是在 1960 年代后期开发的，但随后自然感染 RSV 后，接种疫苗的婴儿会发生疫苗增强疾病 (VED)。肺中过度的炎症免疫病理学可能与 VED 有关，但其潜在机制仍未完全了解。在这项研究中，我们在初免/增强方法中使用了紫外线灭活的 RSV，然后在 BALB/c 小鼠中使用 RSV 攻击来模拟 RSV VED。从感染后第 1 天到第 6 天，研究了小鼠肺组织中的动态病毒载量、细胞因子、组织学和转录组谱。与 PBS 处理的小鼠相比，UV-RSV 疫苗接种导致 Th2 型炎症反应，其特征在于增强的组织病理学，⁺肺中的 CD4 T 细胞。在接种 UV-RSV 的小鼠中观察到几种 Th2 型细胞因子（IL-4、IL-5、IL-10）和 TGF-β）的产生增加，IL-6 和 IL-17 减少。通过 RNA-Seq 鉴定了 PBS 处理或疫苗接种的小鼠与幼稚小鼠之间的总共 5582 个差异表达 (DE) 基因。11 个保守的高影响模块 (HMs) 被识别，主要分为与细胞周期和细胞代谢、信号转导、免疫和炎症反应相关的调节网络。在感染后的早期，与 PBS 处理的小鼠相比，接种疫苗的小鼠在 11 只 HM 中表现出明显降低的 DE 基因表达模式。细胞外基质 (HM5) 和免疫反应 (HM8) 揭示了在早期和晚期时间点，PBS 处理和接种小鼠之间转录物的表达和调节特征存在巨大差异。RT-qPCR 进一步验证了 HM5 和 HM8 网络中高度连接的基因。这些发现揭示了 RSV VED 与免疫反应之间的关系，这可能有利于新型 RSV 疫苗的开发。