Clinic for Poultry and Fish Medicine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria.
Christian Doppler Laboratory for Innovative Poultry Vaccines, University of Veterinary Medicine Vienna, Vienna, Austria.
Front Immunol. 2018 May 28;9:1164. doi: 10.3389/fimmu.2018.01164. eCollection 2018.
Histomonosis is a parasitic disease of gallinaceous birds characterized by necrotic lesions in cacum and liver that usually turns fatal in turkeys while it is less severe in chickens. Vaccination using attenuated has been experimentally shown to confer protection against histomonosis. The protective mechanisms that underpin the vaccine-induced immune response are not resolved so far. Therefore, the actual study aimed to evaluate the location and quantitative distribution patterns of signature cytokines of type 1 [interferon gamma (IFN-γ)] or type 2 [interleukin (IL)-13] immune responses in vaccinated or infected hosts. An intergroup and interspecies difference in the spatial and temporal distribution patterns of cytokine mRNA positive cells was evident. Quantification of cells showed a significantly decreased percentage of IFN-γ mRNA positive cells at 4 days post-inoculation (DPI) in caeca of turkeys inoculated exclusively with the attenuated or the virulent inocula, compared to control birds. The decrement was followed by a surge of cells expressing mRNA for IFN-γ or IL-13, reaching a peak of increment at 10 DPI. By contrast, turkeys challenged following vaccination showed a slight increment of cecal IFN-γ mRNA positive cells at 4 DPI after which positive cell counts became comparable to control birds. The increase in infected birds was accompanied by an extensive distribution of positively stained cells up to the muscularis layer of cecal tissue whereas the vaccine group maintained an intact mucosal structure. In chickens, the level of changes of positive cells was generally lower compared to turkeys. However, control chickens were found with a higher percentage of IFN-γ mRNA positive cells in cecum compared to their turkey counterparts indicating a higher resistance to histomonosis, similar to the observation in immunized turkeys. In chickens, it could be shown that the changes of cytokine-positive cells were related to variations of mononuclear cells quantified by immunofluorescence. Furthermore, gene expression measured by reverse transcription quantitative real time PCR confirmed variations in organs between the different groups of both bird species. Overall, it can be concluded that a proportionally increased, yet controlled, allocation of IFN-γ mRNA positive cells in caeca hallmarks a protective trait against histomonosis.
组织滴虫病是一种寄生在禽类的疾病，其特征为盲肠和肝脏出现坏死病变。在火鸡中，该疾病通常是致命的，而在鸡中则较为温和。实验表明，使用减毒疫苗接种可以提供针对组织滴虫病的保护。然而，目前仍然没有确定疫苗诱导的免疫反应所依赖的保护机制。因此，本实际研究旨在评估在接种或感染宿主中，1 型[干扰素-γ（IFN-γ）]或 2 型[白细胞介素（IL）-13]免疫反应的特征细胞因子的定位和定量分布模式。在接种或感染宿主中，细胞因子 mRNA 阳性细胞的空间和时间分布模式存在明显的组间和种间差异。细胞定量分析显示，在单独接种减毒或强毒接种物的火鸡盲肠中，与对照组鸟类相比，接种后 4 天（DPI）IFN-γ mRNA 阳性细胞的百分比显著降低。此后，细胞表达 IFN-γ 或 IL-13 的 mRNA 出现激增，在 10 DPI 时达到高峰。相比之下，接种后受到挑战的火鸡仅在接种后 4 DPI 时盲肠 IFN-γ mRNA 阳性细胞略有增加，此后阳性细胞计数与对照组鸟类相当。受感染鸟类的增加伴随着大量阳性染色细胞分布到盲肠组织的肌层，而疫苗组则保持完整的黏膜结构。在鸡中，与火鸡相比，阳性细胞变化的水平通常较低。然而，与火鸡相比，对照组鸡的盲肠中 IFN-γ mRNA 阳性细胞的百分比更高，这表明它们对组织滴虫病具有更高的抵抗力，类似于免疫接种火鸡的观察结果。在鸡中，可以表明，免疫荧光定量的单核细胞的变化与细胞因子阳性细胞的变化有关。此外，通过反转录定量实时 PCR 测量的基因表达证实了两种鸟类不同组之间器官的变化。总的来说，可以得出结论，盲肠中 IFN-γ mRNA 阳性细胞的比例增加且受到控制，这是对组织滴虫病的一种保护特征。
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