College of Animal Science and Technology, Shandong Agricultural University, Tai'an, Shandong, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Tai'an, Shandong, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Tai'an, Shandong, China.
College of Animal Science and Technology, Shandong Agricultural University, Tai'an, Shandong, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Tai'an, Shandong, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Tai'an, Shandong, China.
Vet Microbiol. 2021 Apr;255:109033. doi: 10.1016/j.vetmic.2021.109033. Epub 2021 Mar 5.
Tembusu Virus (TMUV), a pathogenic member of Flavivirus family, acts as the causative agent of egg-laying and has severely threatened the duck industry over the past few years. Thus far, the pathogenicity of such virus has been extensively studied, whereas TMUV on immune system has been less comprehensively assessed, especially on ducklings that exhibit more susceptible to TMUV attack. Accordingly, in the present study, 5-day-old ducklings were infected with TMUV-TC2B (10 TCID) via intravenous injection, and mock ones were inoculated with phosphate-buffered saline (PBS) in identical manner as control. At 1 day-post inoculation (dpi), the innate immunity was strongly activated, and reacted rapidly to TMUV invasion, which was reflected as the significantly up-regulated IFN-stimulated genes (ISGs), especially in immune organs (e.g., thymus, bursa of Fabricius (BF) and spleen). Subsequently, under the continuous monitoring, the levels of IgA, IgM and IgG acting as the representative immunoglobulins (Igs) were constantly higher than those of mock ducklings, demonstrating that humoral immunity also played a major role in anti-virus infection. Despite the immune system activated positively, TMUV still caused systemic infection, and in particular, the immune organs were subject to severe damage in the early infection. With our constant observation, the injury of spleen and BF turned out to be getting more serious, and at 6 dpi, TMUV antigen was widely detected in both of two immune organs by immunohistochemistry (IHC) and main histopathological lesion presented as lymphocytopenia. Moreover, the elevated apoptosis rate of splenic lymphocytes and the alteration of immune organ index also revealed the damage of lymphoid organs and similarly, it is worth noting that severe damages were detected in thymus of TMUV-infected ducklings as well. In brief, the present study systematically described the dynamic damage of immune system after being attacked by TMUV and presented insights into the research of pathogenicity.
黄病毒科的一种致病性成员，即鸭坦布苏病毒（TMUV），是产蛋和产卵下降的致病因子，在过去几年中严重威胁了养鸭业。迄今为止，人们广泛研究了这种病毒的致病性，而对 TMUV 对免疫系统的影响研究较少，特别是对更易受 TMUV 攻击的雏鸭。因此，在本研究中，通过静脉注射感染 5 日龄雏鸭 TMUV-TC2B（10TCID），并用磷酸盐缓冲液（PBS）以相同方式接种的雏鸭作为对照。感染后 1 天（dpi），先天免疫系统被强烈激活，并对 TMUV 的入侵迅速做出反应，这表现为 IFN 刺激基因（ISGs）的显著上调，特别是在免疫器官（如胸腺、法氏囊（BF）和脾脏）。随后，在连续监测中，作为代表免疫球蛋白（Igs）的 IgA、IgM 和 IgG 的水平始终高于对照雏鸭，表明体液免疫在抗病毒感染中也发挥了主要作用。尽管免疫系统被积极激活，但 TMUV 仍会引起全身性感染，特别是在早期感染时，免疫器官会受到严重损害。通过我们的持续观察，发现脾脏和 BF 的损伤变得更加严重，在 6dpi 时，免疫组化（IHC）和主要组织病理学病变显示两种免疫器官中广泛检测到 TMUV 抗原，淋巴细胞减少症。此外，脾淋巴细胞凋亡率升高和免疫器官指数改变也揭示了淋巴器官的损伤，同样值得注意的是，在 TMUV 感染的雏鸭中也检测到了胸腺的严重损伤。总之，本研究系统描述了 TMUV 攻击后免疫系统的动态损伤，并为致病性研究提供了新的见解。
