Induction of apoptotic lesions in liver and lymphoid tissues and modulation of cytokine mRNA expression by acute exposure to deoxynivalenol in piglets

Six 1-month-old piglets were intravenously injected with deoxynivalenol (DON) at the concentration of 1 mg/kg body weight, with three pigs each necropsied at 6 and 24 h post-injection (PI) for investigation of hepatotoxicity and immunotoxicity with special attention to apoptotic changes and cytokine mRNA expression. Histopathological examination of the DON-injected pigs revealed systemic apoptosis of lymphocytes in lymphoid tissues and hepatocytes. Apoptosis of lymphocytes and hepatocytes was confirmed by the TdT-mediated dUTP-biotin nick end-labeling (TUNEL) method and immunohistochemical staining against single-stranded DNA and cleaved caspase-3. The number of TUNEL-positive cells in the thymus and Peyer''s patches of the ileum was increased at 24 h PI compared to 6 h PI, but the peak was at 6 h PI in the liver. The mRNA expression of interleukin (IL)-1β, IL-6, IL-18, and tumor necrosis factor (TNF)-α in the spleen, thymus and mesenteric lymph nodes were determined by semi-quantitative RT-PCR, and elevated expression of IL-1β mRNA at 6 h PI and a decrease of IL-18 mRNA at 24 h PI were observed in the spleen. IL-1β and IL-6 mRNA expressions increased significantly at 6 h PI in the thymus, but TNF-α decreased at 6 h PI in the mesenteric lymph nodes. These results show the apoptosis of hepatocytes suggesting the hepatotoxic potential of DON, in addition to an immunotoxic effect on the modulation of proinflammatory cytokine genes in lymphoid organs with extensive apoptosis of lymphocytes induced by acute exposure to DON in pigs.     

NODs/RIP2信号通路关键基因在断奶仔猪不同组织中的mRNA表达

本试验旨在研究核苷酸结合寡聚化结构域蛋白/受体相互作用蛋白2(NODs/RIP2)信号通路关键基因在断奶仔猪不同组织的分布情况。选择12头杜×长×大断奶仔猪,屠宰,取脾脏、胸腺、肠道淋巴结、下丘脑、垂体、肾上腺、肝脏、腓肠肌、皮下脂肪、空肠和回肠组织。应用实时荧光定量PCR技术测定NODs/RIP2信号通路关键基因,包括NOD1、NOD2和RIP2在各组织的mRNA表达水平。结果表明:NOD1、NOD2和RIP2在所检测的11个组织中均有表达。NOD1 mRNA在肠道淋巴结和下丘脑表达量较高;NOD2 mRNA在肠道淋巴结、脾脏、下丘脑和胸腺表达量较高;RIP2 mRNA在肠道淋巴结、胸腺和脾脏表达量较高。NODs/RIP2信号通路关键基因在不同组织中表达差异较大,可能与仔猪各组织对病原的识别和抵抗能力有关。     

不同毒力猪繁殖与呼吸综合征病毒对仔猪肺和外周免疫器官损伤的研究

为研究不同毒力的PRRSV对仔猪肺脏和外周免疫器官损伤的差异,本实验分别采用PRRSV变异株(HuN4株)和PRRSV经典株(CH-1a株)感染35日龄健康的断奶仔猪,并在感染后0 d、3 d、7 d、10 d和14 d各迫杀3头,检测肺、颌下淋巴结、肠系淋巴结、腹股沟淋巴结、扁桃体和脾脏的病毒载量及病理变化情况,同时检测血清中抗PRRSV的抗体水平。结果表明:感染后3 d肺脏及各免疫器官可检测到病毒,HuN4感染组病毒载量比CH-1a感染组病毒载量高1 000倍;HuN4感染组病毒载量峰值出现在感染后10 d,而CH-1a感染组维持着较低水平的病毒载量。组织病理学检测显示HuN4感染组淋巴结内淋巴细胞显著减少,呈空泡状;CH-1a感染组淋巴结内淋巴细胞轻度减少,呈星隙状。本实验表明HuN4株比CH-1a株对肺和外周免疫器官造成更严重的损伤。     

Effect of bovine colostrum supplementation on cytokine mRNA expression in weaned piglets

The aim of this study was to evaluate the influence of bovine colostrum supplementation on the immune Th1/Th2 response in weaned piglets. After weaning at 21 d, 3 groups of 7 piglets were fed ad libitum with a starter diet and received daily 0, 1 or 5 g of spray-dried bovine colostrum. Spleen and gut-associated lymphoid tissues (GALT): ileal Peyer's patch (iPP), jejunum wall (JW) and mesenteric lymph node (MLN)) biopsies were collected on each piglet after 3 wk of treatment and analysed for their cytokine mRNA expression (IL-2, IL-4, IL-10, IL-12 and IFNγ) by RT-PCR. The supplementation with bovine colostrum induced an increase (P < 0.05) in IL-12 in the JW, in IL-2, IL-10 and IL-12 in the MLN and in IL-4, IL-10 and IL-12 in the iPP. In the latter, bovine colostrum also decreased IFN-γ production (P < 0.01). Finally, no effect of the treatments was recorded in the spleen. These results suggest an immunomodulatory effect of bovine colostrum on the GALT, which responded by producing at different levels both Th1 pro-inflammatory cytokines (IL-2, IFN-γ and IL-12) and Th2 anti-inflammatory cytokines (IL-4 and IL-10). This Th1/Th2 bipolar response protects the weaned piglets from both allergic (food) and infectious (pathogens) diseases.     

Apoptosis in normal lymphoid organs from healthy normal, conventional pigs at different ages detected by TUNEL and cleaved caspase-3 immunohistochemistry in paraffin-embedded tissues

The frequency and the distribution of apoptotic cells were investigated in formalin-fixed paraffin-embedded lymphoid tissues from healthy conventional pigs at four different ages (6 days, 2 months, 3.5 months and 5 months). Samples of tonsil, mesenteric lymph node, spleen, thymus and Peyer's patches were histologically processed and apoptosis evaluated with the TUNEL reaction and cleaved caspase-3 immunohistochemistry. In each technique, quantification of positive labelling was done for each particular lymphoid tissue area. The labelling pattern and distribution were similar for TUNEL and cleaved caspase-3. TUNEL stained mainly apoptotic bodies inside macrophages, but signal was also seen in free apoptotic bodies and in the nuclei of lymphocyte-like cells. The anti-cleaved caspase-3 antibody labelled mainly nuclei of lymphocyte-like cells. All tissues presented a similar distribution pattern of apoptosis, except for the 6-day-old group. In this group, a scattered distribution of positive cells was detected in tonsil, lymph node and spleen. In the tonsil and mesenteric lymph nodes from the older pigs, follicular areas presented higher amounts of positive cells than interfollicular areas. Moreover, the splenic white pulp showed more positive reaction than the red pulp, especially when they included germinal centres. In all groups, the follicular areas of ileal Peyer's patches presented more labelled cells than the dome and the lamina propria. In the thymus, the higher apoptotic rates were found in the cortex. In general, TUNEL yielded higher rates of positive cells than cleaved caspase-3 immunolabelling. A good correlation between the two techniques was found for thymus, tonsil and mesenteric lymph node, but not for Peyer's patches and spleen. This study describes a detailed histochemical characterization of apoptosis in pig lymphoid tissues using TUNEL and a cleaved caspase-3 immunolabelling at different ages. Moreover, our results indicate that TUNEL and cleaved caspase-3 techniques can be equivalent only when tissues have a high or low levels of apoptosis, since a considerable discrepancy was found in intermediate situations. Data from this study should be useful for future comparative studies under disease conditions.     

PRRSV SC-1株在人工感染仔猪体内的分布

为研究猪繁殖与呼吸综合征病毒(PRRSV)在感染猪体内各器官组织的分布,用PRRSV SC-1株人工感染健康断奶仔猪,接毒后23 d,无菌采集试验猪器官组织,用RT-PCR检测其中病毒核酸分布情况。结果显示,心脏、脾脏、肺脏、肾脏、支气管淋巴结、肠系膜淋巴结、腹股沟淋巴结、髂内淋巴结内有病毒核酸,在所有试验猪的肺脏、腹股沟淋巴结都检测到了病毒核酸。本研究结果为PRRS诊断及病毒分离鉴定提供了一定参考依据。     

复合植物精油对脂多糖诱导的断奶仔猪免疫应激的影响

试验旨在研究复合植物精油（OCT）对脂多糖（LPS）诱导的断奶仔猪的免疫应激的影响。试验选取28日龄左右的杜×长×大三元杂交仔猪，随机分成3个处理组：对照组（基础日粮，注射生理盐水），LPS组（基础日粮，注射LPS），OCT组（基础日粮+50 mg/kg OCT，注射LPS）。每组8个重复，每个重复1头猪。于试验第21天注射LPS（100 μg/kg体重）或等体积的生理盐水，注射3 h后前腔静脉采血进行白细胞分类计数；6 h后屠宰，取胸腺、脾脏，-80℃保存，用于测量胸腺、脾脏免疫相关基因白介素-4（IL-4）、白介素-6（IL-6）、白介素-10（IL-10）、肿瘤坏死因子（TNF-α）、核因子（NF-κB）以及转录相关基因转录激活因子3（STAT3）的基因相对表达量。结果表明：①与对照组相比，LPS刺激降低了仔猪血液中白细胞、中性粒细胞、淋巴细胞、单核细胞及嗜酸性粒细胞数量（P<0.05）；与LPS组相比，日粮中添加OCT提高了白细胞的数量（P<0.05）；②与对照组相比，LPS刺激上调了脾脏、胸腺IL-6、STAT3 mRNA水平（P<0.05），下调了脾脏IL-4、TNF-α及胸腺IL-4、TNF-α、NF-κB mRNA水平（P<0.05）；与LPS组相比，添加OCT下调了脾脏、胸腺IL-6、STAT3 mRNA水平（P<0.05）；上调了胸腺IL-4、IL-10、TNF-α、NF-κB的mRNA水平（P<0.05）。综合上述结果，LPS诱导发生了仔猪免疫应激，OCT在一定程度具有缓解作用。     

Apoptosis in the lymphatic organs of piglets inoculated with classical swine fever virus

The involvement of apoptosis in the lymphatic organs of piglets infected with classical swine fever (CSF) virus was investigated. Piglets were inoculated with CSF virus and 3, 5, 7 and 10 days post inoculation (DPI), the thymus, spleen and lymph node were examined. In the thymus cortex, macrophages phagocytizing the nuclear remnants or apoptotic bodies increased after 3 DPI. Thymus atrophy due to the loss of the cortex increased markedly during the observation period. Compact and shrunken nuclei indicating apoptosis were observed in the spleen and lymph node. DNA fragmentation was detected in the nuclei of lymphocytes in the thymus, spleen and lymph nodes, as well as at sites of focal necrosis. Using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling method, ultrastructural characteristics of apoptosis, i.e. margination of condensed nuclear chromatin, were observed in the lymphatic organs from 2 DPI onward. These results suggest that apoptosis is involved in the pathology of CSF.     

Increased expression of the peroxisome proliferator-activated receptor gamma in the immune system of weaned pigs after Escherichia coli lipopolysaccharide injection

Peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the nuclear hormone receptor superfamily, has been implicated in regulation of immunity and inflammation in rodents and humans. The objective of the current study was to investigate whether the expression of PPARgamma was altered in the immune system of weaned pigs after Escherichia coli lipopolysaccharide (LPS) injection. PPARgamma expression was investigated in the thymus, spleen, mesenteric lymph node and peripheral white blood cells of weaned pigs (8.54+/-0.24 kg BW) after LPS injection (100 microg/kg BW, n=6) and controls (sterile saline, n=6), by using real-time polymerase chain reaction, Western blot analysis, and immunohistochemistry. Plasma pro-inflammatory cytokines and hormones were also assessed. LPS triggered PPARgamma mRNA and protein expression in the thymus (P<0.05, 4.24-fold; P<0.10, 1.46-fold), spleen (P<0.10, 2.75-fold; P<0.05, 1.84-fold), mesenteric lymph node (P<0.05, 4.32-fold; P<0.05, 1.96-fold) and peripheral white blood cells (P<0.001, 24.44-fold; P<0.001, 1.58-fold). The LPS-injected pigs showed an increase in PPARgamma staining in splenic corpuscle and periarterial lymphatic sheath of white pulp (P<0.05) and red pulp (P<0.001) of spleen, and in medullas of thymus lobule of thymus (P<0.05), and in thymus-dependent area of mesenteric lymph node (P<0.05) compared to the control pigs. Concurrent with up-regulation of PPARgamma expression, LPS induced increases in plasma interleukin-6 (P<0.001), tumor necrosis factor-alpha (P<0.001), cortisol (P<0.001), prostaglandin E(2) (P<0.01) and 15-deoxy-Delta(12,14)-prostaglandin J(2) (15 d-PGJ(2)) (P<0.05), and decreases in plasma insulin (P<0.10) and insulin-like growth factor-1 (P<0.001). These results suggest that induction of PPARgamma expression in immune system may be associated with the release of the natural PPARgamma activating ligand 15 d-PGJ(2), and play an important role in host response to immunological stress. Additionally, it is possible that PPARgamma would be a new therapeutic target in treatment of immunological stress of livestock.     

Oral transmission of transmissible gastroenteritis virus by muscle and lymph node from slaughtered pigs

A study was conducted in the USA to determine whether transmissible gastroenteritis (TGE) virus could be transmitted from carcases of slaughtered pigs. Transmissible gastroenteritis virus was transmitted to 6-day-old piglets by dosing with homogenates of muscle and lymph node collected from 500 clinically normal pigs at the time of slaughter. All piglets in 2 separately housed litters showed clinical signs of TGE with 5 piglets dying within 10 d of oral dosing with homogenates. Transmissible gastroenteritis virus was isolated from 2 of these piglets and all piglets developed TGE antibody. Transmissible gastroenteritis virus was not isolated in tissue culture from muscle and lymph node homogenates, but was isolated from 4 (0.8%) of 500 tonsil samples collected from the same pigs. A survey of 250 serum samples provided an estimate of the prevalence of slaughtered pigs with TGE antibody of 34.8% in the sample population. The results indicate that carcases of some pigs from TGE endemic areas contain viable TGE virus, and that there would be a substantial risk of introducing TGE virus into Australia by the importation of uncooked pig meat from these areas.     

Molecular Mechanism of the Inflammatory Response Induced by Enterotrxigenic E. coli K88 in Piglets

To investigate the molecular mechanism of the inflammatory response in the piglets infected with enterotoxigenic E. coli (ETEC) K88, piglets were infected with ETEC K88,the IL-8 content in serum of piglets were assayed by ELISA,and the mRNA relative expression levels of TLR2/4 and its signal transduction pathway related genes (MyD88,Tollip and Bcl3) in mesenteric lymph nodes were detected by quantitative Real-time PCR. The results showed that compared with control group,the content of IL-8 in serum and the expressions of TLR2/4 in lymph nodes were all extremely significantly or significantly increased at 6 and 24 h after infection (P<0.01;P<0.05),and the IL-8 content and TLR2/4 mRNA expression at 24 h after infection were all significantly lower than those at 6 h after infection (P<0.05).In addition,the expressions of MyD88,Tollip and Bcl3 in lymph nodes were all extremely significantly increased at 24 h after infection compared with control group (P<0.01), but there was no significant difference between experimental group and control group at 6 h after infection (P>0.05). In conclusion,ETEC K88 infected piglets might produce inflammatory cytokines IL-8 through the TLR2/4-MyD88 signaling pathway,which could promote the inflammatory reaction in piglets. This inflammatory response might be regulated by Tollip and Bcl3,which could weak the inflammatory intensity in piglets.     

产肠毒素大肠杆菌K88诱导仔猪炎症反应的分子机制

为探讨产肠毒素大肠杆菌（ETEC） K88感染仔猪发生炎症反应的分子机制,试验用ETEC K88灌服断奶仔猪,ELISA法检测攻毒后仔猪血清中白细胞介素8（IL-8）含量,实时荧光定量PCR方法检测淋巴结中Toll样受体2（TLR2）、Toll样受体4（TLR4）及其信号通路相关基因（髓样分化因子88（MyD88）、Toll相互作用蛋白（Tollip）、B细胞淋巴瘤因子3（Bcl3））的mRNA相对表达水平。结果发现,仔猪攻毒ETEC K88后6和24 h血清IL-8含量和淋巴结TLR2/4的表达水平均极显著或显著高于对照组（P<0.01;P<0.05）,且感染后24 h显著低于感染后6 h（P<0.05）;仔猪感染ETEC K88后24 h淋巴结中MyD88、Tollip和Bcl3的表达水平均极显著高于对照组（P<0.01）,但是感染后6 h时与对照组相比均无显著差异（P>0.05）。综上所述,ETEC K88感染仔猪可能是通过TLR2/4-MyD88信号通路产生炎症因子IL-8,促使仔猪出现炎症反应,且该炎症反应可能受Tollip和Bcl3蛋白的调控而被减弱。     

Expression of inflammatory cytokine mRNA in lymphoid tissue from swine experimentally infected with Mycobacterium avium serovar 2

OBJECTIVE: To evaluate in situ expression of inflammatory cytokine mRNA in lymphoid tissue of swine experimentally infected with Mycobacterium avium serovar 2. ANIMALS: 7 noninfected pigs and 7 pigs infected with M. avium serovar 2. PROCEDURE: Expression of mRNA of inflammatory cytokines such as tumor necrosis factor alpha (TNFalpha), interleukin (IL)-1beta IL-6, and IL-8 in formalin-fixed paraffin-embedded blocks of lymphoid tissue (lymph nodes and tonsil) of swine experimentally infected with M. avium serovar 2 was compared with that of noninfected pigs. Tissues were evaluated by use of morphologic localization of cytokine mRNA, using in situ hybridization at 160 days after inoculation. RESULTS: A noticeable increase in mRNA expression for TNFalpha and mild increases in mRNA expression of IL-8 and IL-1beta were detected in mandibular lymph nodes from infected swine, compared with noninfected swine. Mild increase in mRNA expression for 1L-6 also was observed in tonsils from infected swine. Cytokine mRNA was detected in macrophages and lymphocytes, primarily within cortical follicles and adjacent mantle zones. CONCLUSIONS AND CLINICAL RELEVANCE: Expression of mRNA for inflammatory cytokines was increased in lymphoid tissue of infected swine, possibly resulting from local factors on, or secreted by, M. avium. These results suggest that alterations in cytokine mRNA expression are important in the pathogenesis and clinical course of mycobacteriosis in swine. Modulation of the immune response by vaccines that selectively target cytokine expression and secretion in response to mycobacterial challenge may be effective in prevention of mycobacteriosis in swine.     

Influence of bestatin, an inhibitor of aminopeptidases, on T and B lymphocyte subsets in mice

Bestatin, a low-molecular weight dipeptide, is a potent inhibitor of aminopeptidase N which has been demonstrated to have antitumor and immunomodulatory effects. The effects of bestatin (10, 1 and 0.1 mg/kg) administered intraperitoneally once, five or ten times to mice on the total number of lymphocytes in the thymus, spleen and mesenteric lymph nodes and the percentage and the absolute number of T cell subsets (CD4+CD8+, CD4-CD8-, CD4+, CD8+) in the thymus and T (CD3+, CD4+, CD8+) and B (CD19+) lymphocytes in the spleen and mesenteric lymph nodes were studied. It has been found that bestatin administered ten times at doses of 10, 1 and 0.1 mg/kg increased the total number of thymocytes, splenocytes and lymphocytes of mesenteric lymph nodes. Bestatin also changed the percentage and the absolute number of T cell subsets in the thymus and T and B lymphocytes in the peripheral lymphatic organs. Five and ten exposures to bestatin (10, 1 and 0.1 mg/kg) increased the absolute count of both immature CD4+CD8+ and CD4-CD8- thymic cells. Moreover, both a single and multiple administration of bestatin (1 and 0.1 mg/kg) decreased the percentage and absolute count of CD3+ splenocytes and mesenteric lymph node cells with corresponding decreases in the percentage and absolute count of CD4+ and CD8+ cells. Both a single and multiple administration of bestatin at all the doses under investigation augmented the percentage and the absolute count of CD19+ (B lymphocytes) in the peripheral lymphatic organs. The results of the study show that there is a relationship between the effect induced by bestatin and the dose of the drug as well as the number of doses applied. The strongest effect on the T and B lymphocyte subsets was noted after five injections of bestatin at doses of 1 and 0.1 mg/kg.     

Analysis of constitutive cytokine expression by pigs infected in-utero with porcine reproductive and respiratory syndrome virus

To investigate cytokine alterations in pigs infected in-utero with porcine reproductive and respiratory syndrome virus (PRRSV), constitutive mRNA expression by peripheral blood mononuclear cells (PBMCs) was measured. PBMC from in-utero PRRSV-infected pigs displayed significantly increased IL-6, IL-10, and IFN-gamma mRNA expression at 0 and 14 days of age compared with age-matched control pigs. There were no significant differences in IL-2, IL-4, and IL-12 mRNA expression between in-utero PRRSV-infected and control pigs. However, the IL-10/IL-12 ratio was significantly increased in in-utero PRRSV-infected pigs at 0 and 14 days of age, suggesting the imbalance of IL-10 and IL-12 mRNA production. The abnormal mRNA expression of cytokines in in-utero PRRSV-infected pigs occurred concurrently with a significant decrease in the CD4(+)/CD8(+) T-cell ratio in peripheral blood. PRRSV was not isolated from the sera of pigs at 9 weeks of age that had been viremic at 0 and 14 days old. Delayed type hypersensitivity (DTH) responses to Tuberculin and analysis of cytokine mRNA expression by PBMC showed that cell-mediated immune response and cytokine message profiles in pigs infected in-utero with PRRSV had returned to levels similar to those of control pigs by 9 weeks of age. We conclude that in-utero infection with PRRSV results in significant alteration of cytokine mRNA expression that may cause transient immunomodulation. However, at 10 weeks of age the pigs' immune responses seemed to recover. This may help to understand the immunopathogenesis of in-utero PRRSV infection and the increased susceptibility to secondary bacterial pathogens in neonatal piglets.     

Effects of weaning on somatotrophic gene expression and circulating levels of insulin-like growth factor-1 (IGF-1) and IGF-2 in pigs

The present study evaluated somatotrophic gene expression in liver, muscle and adipose tissue 4 d after weaning, a time point corresponding to greatly reduced serum concentrations of insulin-like growth factor (IGF)-1 and IGF-2 in pigs. Two-week-old barrows were either cross-fostered to a sow (SOW, N = 8) or weaned and fed a phase 1 diet containing either 0 or 7% spray-dried plasma (NP, N = 8 and SDP, N = 8; respectively). Piglets were allocated such that two size groups were equivalently represented in each experimental group (small, 3.5–4.3 kg and large, 4.6–5.7 kg). Animals were weighed daily and sacrificed 4 d after weaning for blood and tissue collection. Daily gains of the SOW piglets were significantly greater than those of the weaned pigs for the first 3 d of the experiment (P < 0.0001). Weight gains in the SOW and SDP pigs between d 3 and 4 were equivalently elevated relative to the NP pigs (P < 0.0001). Serum IGF-1 and IGF-2 concentrations were decreased in both NP and SDP compared to SOW (P < 0.0001). Serum IGF-2 levels were significantly lower in small piglets (P = 0.006). A Weaning Group X Size interaction was noted for liver IGF-2 mRNA (P < 0.03), reflecting a higher level of expression in large SOW piglets relative to small SOW piglets. Weaning did not affect IGF-1, IGF-2, or growth hormone (GH) receptor mRNA levels in liver, muscle, or fat (P > 0.05). Liver IGF-binding protein (IGFBP)-3 and acid-labile subunit (ALS) mRNA levels also were unaffected by weaning. Small pigs had lower levels of liver ALS (P = 0.0003), muscle IGF-2 (P = 0.02), and muscle GH receptor (P = 0.006) mRNAs. In contrast, adipose tissue IGF-1 and IGF-2 mRNA levels were greatest in the small piglets (P = 0.001 and 0.029, respectively).     

The combination of deoxynivalenol and zearalenone at permitted feed concentrations causes serious physiological effects in young pigs

This study was to investigate the effects of the combination of deoxynivalenol (DON) and zearalenone (ZON) on pigs. Twenty-four weaning piglets were divided into a control group fed a diet free of mycotoxins and a toxin group fed a diet containing 1 mg/kg DON and 250 µg/kg ZON. The results showed that supplementation of DON and ZON in diets had extensive effects on pigs. More specifically, DON and ZON caused levels of total protein, albumin, and globulin in sera to decrease (p < 0.05) by 14.5%, 6.5% and 11.3%, respectively, and at the same time increased (p < 0.05) the serum enzyme activities of γ-glutamyltransferase, aspartate aminotransferase and alanine aminotransferase by 72.0%, 32.6% and 36.6%, respectively. In addition, DON and ZON decreased (p < 0.05) the level of anti-classical swine fever antibody titers by 14.8%. Real-time PCR showed that DON and ZON caused the mRNA expression levels of IFN-γ, TNF-α, IL-2, to decrease (p < 0.05) by 36.0%, 29.0% and 35.4%, respectively. Histopathological studies demonstrated that DON and ZON caused abnormalities in the liver, spleen, lymph nodes, uterus, and kidney. The concentrations of DON and ZON used in this study are in line with the published critical values permitted by BML. Our study clearly put the standard and adequacy of safety measures for these toxins into question. The authors suggest that with the increasing availability of cellular and molecular technologies, it is time to revisit the safety standards for toxins in feeds so as to make feeds safer, providing consumers with safer products.     

日粮中添加铁对绵羊免疫器官组织结构和铁含量的影响

为研究日粮中不同铁水平对绵羊免疫功能的影响，探究绵羊饲养过程中铁过量的风险，试验在绵羊基础日粮中分别添加铁500、1 000、1 500 mg/kg（硫酸亚铁形式），饲养75 d后宰杀，采取绵羊免疫器官（脾脏、胸腺、肝门淋巴结、十二指肠淋巴结及腭扁桃体），应用传统病理学方法观察以上器官的组织结构变化、含铁血黄素分布，并测定组织铁含量的变化情况。结果显示，绵羊饲喂过量铁后，脾脏白髓占比减小，淋巴细胞数量减少、排列疏松，伴有肿大、空泡化现象，红髓内有大量含铁血黄素沉积；胸腺皮质区变薄，髓质区变厚且融合，胸腺小体数量减少、结构模糊；肝门淋巴结、十二指肠淋巴结皮质与髓质区变薄、界限模糊，皮质淋巴窦与髓窦间隙增大，淋巴小结结构模糊；腭扁桃体实质内淋巴小结数量减少，毛细血管后微静脉有充血现象。饲喂过量铁后，各免疫器官组织铁含量均升高，其中脾脏内铁含量最多，腭扁桃体内最少，铁低、中、高剂量组脾脏铁含量极显著高于对照组（P<0.01）。结果表明，饲喂过量铁后，绵羊免疫器官组织结构均遭到不同程度破坏，且随着铁添加量越多，组织结构破坏程度越明显；各免疫器官中铁蓄积量与日粮中铁添加水平呈正相关，摄入过量铁严重影响绵羊免疫功能，因此在绵羊饲养过程中，要严格遵守美国NRC（1985）饲料标准，日粮中铁水平不要超过500 mg/kg。     

鸡IL—15基因的分子克隆及其有关特性的研究

实验应用聚合酶链式反应技术从鸡脾淋巴细胞中克隆得到了白细胞介素-15基因，序列分析表明与已发表的鸡白细胞介素-15基因完全一致，核苷酸序列和推导的氨基酸序列与牛的最接近，同源性分别为46%和31%，与哺乳动物白细胞介素-15序列类似，有4个高度保守的半胱氨酸残基，同时本研究也用此方法对鸡脾脏、法氏囊、胸腺、哈德氏腺和盲肠扁桃体等淋巴器官的淋巴细胞中鸡白细胞介素-15mRNA的表达进行了研究，结果表明这些器官的淋巴细胞均表达mRNA。在实验还用有丝分裂原ConA对鸡脾淋巴细胞进行活化，观察活化的淋巴细胞表达白细胞介素-15mRNA的情况，结果发现白细胞介素-15mRNA在活化的脾淋巴细胞中表达量升高。     

Spray-dried porcine plasma affects intestinal morphology and immune cell subsets of weaned pigs

The aim of this study was to evaluate the effects of dietary spray-dried porcine plasma (SDPP) on the productive performance, intestinal morphology and leukocyte cell subsets of piglets. Sixteen early-weaned piglets (20 ± 2 d) were distributed into two dietary treatments: 1) free access to control diet or 2) 6% SDPP in the control diet instead of soy-protein concentrate. Intestinal morphometry of the small and large intestine, haematology and immune cell flow cytometric analysis of blood, ileo-colic lymph node and ileal Peyer's patches were performed in all pigs. Although SDPP treatment did not increase growth performance, it improved feed efficiency. We observed that SDPP diminishes blood monocytes, and macrophages (SWC3+), B lymphocytes (CD21+) and γδ T cells (γδTCR+) in gut lymphoid tissues. SDPP-treated piglets also showed lower intraepithelial lymphocyte numbers and lamina propria cell density in the small and large intestine. All these results suggest lower activation of the immune system of the SDPP-piglets during the post-weaning period. Moreover, the use of SDPP can be considered a valid alternative to antibiotic growth promoters.