Kristeen-Teo Y W, Yeap S K, Tan S W, Omar A R, Ideris A, Tan S G, Alitheen N B
Institute of Bioscience, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.
BMC Vet Res. 2017 May 31;13(1):151. doi: 10.1186/s12917-017-1071-y.
Virulent Newcastle disease virus (NDV) was reported to cause rapid depletion of chicken bursa of Fabricius. Severe pathological condition of the organ is commonly associated with high levels of virus replication, intense inflammatory response and also the degree of apoptosis. In this study, the responses of chicken bursa of Fabricius infected with two different strains of velogenic NDV, namely AF2240 and IBS002, were investigated by observing cell population changes, oxidative stress, viral replication and cytokine expression in the organ. Subsequently, apoptosis of enriched bursal IgM+ cells was determined to help us elucidate possible host pathogen relationships between the chicken bursa of Fabricius and NDV infection.
The depletion of IgM+ cells and infiltration of macrophages were observed to be higher in bursa infected with AF2240 as compared to IBS002. In line with the increment of the macrophage population, higher nitric oxide (NO) and malondialdehyde (MDA) contents which indicated higher oxidative stress were also detected in bursa infected with NDV AF2240. In addition, higher pro-inflammatory cytokines and chemokine gene expression such as chicken CXCLi2, IL-18 and IFN-γ were observed in AF2240 infected bursa. Depletion of IgM+ cells was further confirmed with increased cell death and apoptosis of the cells in AF2240 infected bursa as compared to IBS002. However, it was found that the viral load for NDV strain IBS002 was comparatively higher than AF2240 although the magnitude of the pro- inflammatory cytokines expression and cell apoptosis was lower than AF2240.
The results of our study demonstrated that infection of NDV strains AF2240 and IBS002 caused apoptosis in bursa IgM+ cells and its severity was associated with increased expression of pro-inflammatory cytokines/chemokine, macrophage infiltration and oxidative stress as the infection duration was prolonged. However, of the two viruses, we observed that NDV AF2240 induced a greater magnitude of apoptosis in chicken bursa IgM+ cells in comparison to IBS002. This might be due to the high level of oxidative stress and inflammatory cytokines/chemokine as well as lower IL10 expression which subsequently led to a high rate of apoptosis in the chicken bursa of Fabricius although the detected viral load of AF2240 was lower than IBS002.
据报道，强毒新城疫病毒（NDV）可导致鸡法氏囊迅速萎缩。该器官的严重病理状况通常与病毒的高水平复制、强烈的炎症反应以及细胞凋亡程度有关。在本研究中，通过观察细胞群体变化、氧化应激、病毒复制及器官中细胞因子表达，研究了感染两种不同强毒株NDV（即AF2240和IBS002）的鸡法氏囊的反应。随后，测定富集的法氏囊IgM+细胞的凋亡情况，以帮助阐明鸡法氏囊与NDV感染之间可能的宿主-病原体关系。
与IBS002相比，感染AF2240的法氏囊中IgM+细胞的减少和巨噬细胞的浸润更为明显。随着巨噬细胞数量的增加，在感染NDV AF2240的法氏囊中还检测到较高的一氧化氮（NO）和丙二醛（MDA）含量，这表明氧化应激水平更高。此外，在感染AF2240的法氏囊中观察到较高的促炎细胞因子和趋化因子基因表达，如鸡CXCLi2、IL-18和IFN-γ。与IBS002相比，感染AF2240的法氏囊中细胞死亡和凋亡增加，进一步证实了IgM+细胞的减少。然而，发现NDV毒株IBS002的病毒载量相对高于AF2240，尽管促炎细胞因子表达和细胞凋亡的程度低于AF2240。
我们的研究结果表明，NDV毒株AF2240和IBS002的感染导致法氏囊IgM+细胞凋亡，随着感染时间的延长，其严重程度与促炎细胞因子/趋化因子表达增加、巨噬细胞浸润和氧化应激有关。然而，在这两种病毒中，我们观察到与IBS002相比，NDV AF2240在鸡法氏囊IgM+细胞中诱导的凋亡程度更大。这可能是由于氧化应激和炎性细胞因子/趋化因子水平较高以及IL10表达较低，随后导致鸡法氏囊中凋亡率较高，尽管检测到的AF2240病毒载量低于IBS002。
