Pathogenesis of canine parvovirus-2 in dogs: histopathology and antigen identification in tissues

The pathogenesis of canine parvovirus-2 was studied in orally inoculated conventional dogs using histopathological and peroxidase anti-peroxidase staining techniques. Lymphoid necrosis and depletion of lymphocytes from lymphoid tissues were most notable on days 5 and 6 after exposure. Lymphocyte hyperplasia occurred following day 7. Epithelial cell changes in segments of the small intestine were more severe on days 6 to 9 after exposure in areas associated with Peyer's patches and in the upper segments of the small intestine. The lymphocyte was the primary infected cell. Virus infected cryptal epithelial cells were not detected until 24 hours after the identification of infected cells in lymphoid tissues on day 4 after exposure. The majority of virus infected epithelial cells were found in crypts intimately associated with or adjacent to Peyer's patches in the upper segments of the small intestine.     

Light and electron microscopic findings in the intestine of spontaneous and experimentally-produced African swine fever]

Light and electron microscopical studies were carried out after experimental induced and spontaneous infection with African swine fever virus. The experimental infection was performed in 18 pigs divided into two groups consisting of 9 animals. The pigs of group I were inoculated with virulent isolate E 70, those of group II with attenuated isolate E 75. Two infected pigs of group I and one control animal were killed on days 3, 5 or 7 p.i., two pigs of group II and one control animal were killed on days 9, 11 or 13 p.i. Additionally 19 spontaneous infected and seropositive animals and two seronegative pigs without clinical signs were examined. Infection with African swine fever virus resulted in slight morphological alterations of the intestine. The pathological findings showed a more intense involvement of the large intestine, especially the caecum and colon, than the small intestine, where the ileum was mostly affected. In all three groups edema and vacuolisation could be observed in endothelial cells. In spite of beginning degenerative signs, especially after spontaneous infection, the fenestrated structure of the endothelium was conserved in most of the cases. In animals infected with virulent isolate the vascular lumina contained aggregations of fibrin, which was severe pronounced in the pigs of the other groups. In the area of these alterations disturbance of permeability with extravasation could be found. In all groups single virions or virus aggregates could be identified in concave depressions of the erythrocyte membrane or free within the blood plasma, in some cases enveloped by a plasma-like material.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electron microscopic studies of the morphogenesis of duck enteritis virus

The morphogenesis of duck enteritis virus (DEV) and distribution in vivo were observed by electron microscopy after ducks were infected experimentally with DEV virulent strain. The investigation showed that a few typical herpesvirus virions and nucleocapsids were first observed in the spleen, thymus, and bursa of Fabricius (BF), and many nucleocapsids, mature viruses, and viral inclusion bodies could be found in the nucleus and cytoplasm of infected liver, small intestine, spleen, thymus, and BF when the ducks died. Nucleocapsids assembled both in nucleus and cytoplasm and could be divided into four different types according to their structures. Typical herpesvirus, light particles (L-particles), and virions without tegument could be observed at the same time. With the replication, assembly, and maturation of the viruses, intracytoplasmic and intranuclear inclusion bodies, electron-density particles, microtubules, hollow tubes, and coated electron-density bodies were observed in infected cells.     

复方中药口服液抗腹泻作用机理研究

目的：研究复方中药口服液抗腹泻的作用机理。方法：以发病仔猪病料（小肠及内容物）、蓖麻油和番泻叶分别对小鼠灌胃,后灌服复方中药口服液,研究复方中药口服液对小鼠攻毒后的保护作用。结果：病料攻毒后小鼠的主要病理变化在肝、胆及小肠,复方中药口服液对病料和蓖麻油灌胃致小鼠腹泻具有明显的治疗作用。结论：复方中药口服液抗腹泻作用主要表现在对小肠的保护作用。     

猪德尔塔冠状病毒感染对初生仔猪小肠杯状细胞数量及Hes1和MUC2表达的影响

旨在探讨猪德尔塔冠状病毒(PDCoV)感染仔猪对小肠杯状细胞(goblet cell,GC)的影响,将6头未吃初乳的初生仔猪静养2 d后随机分为感染组(n = 3)和对照组(n=3),感染组仔猪口服接种5 mL 1×105 TCID50·mL-1 PDCoV-CHN-HG-2017毒株,对照组仔猪口服5 mL DMEM...     

Follicle associated epithelium of the gut associated lymphoid tissue of cattle

The morphology of the gut-associated lymphoid tissue of the small and large intestine in three gnotobiotic calves was examined by scanning and transmission electron microscopy, and the distribution of specialized membranous cells present in the follicle associated epithelium was defined. Isolated follicles remaining in the ileum of a cow after involution of the continuous Peyer's patch were examined by scanning electron microscopy. The presence of membrane-bound particles, reported to be exclusively associated with the continuous Peyer's patch, was investigated in other gut-associated tissue of the small and large intestine of the calf. The presence of two types of follicle associated epithelium in the small intestine of the calf was confirmed, and the follicle associated epithelium of the large intestine proved to be a homogeneous population of specialized membranous cells, similar to that of the continuous Peyer's patch of the small intestine. In the discrete Peyer's patches, some specialized membranous cells were completely hidden by adjacent enterocytes and could only be identified by cytoplasmic extensions into the intestinal lumen. In the proximal part of the continuous Peyer's patch, a transitional zone was detected where the follicle associated epithelium of some doomed villi was composed of a homogeneous population of specialized membranous cells, while the epithelium covering other doomed villi consisted of a mixture of absorptive and specialized membranous cells, usually only found in the discrete Peyer's patches. Membrane-bound particles were observed associated with gut-associated lymphoid tissue in the small and large intestine.     

Enteropathogenicity of Dutch and German avian reoviruses in SPF white leghorn chickens and broilers

The enteropathogenicity of avian reoviruses (ARVs), isolated from chickens affected with malabsorption syndrome (MAS) from The Netherlands and Germany was studied. In the first trial seven different ARVs isolated from MAS cases were inoculated in 1-day-old specific pathogenic free (SPF) white leghorns. The pathogenicity was compared with 2 ARVs isolated from cases of tenosynovitis, namely reference strain S1133 and a Dutch strain. Although a difference in the severity of the clinical disease was observed, all reoviruses could induce vacuolar degeneration and sloughing of the epithelium of the small intestine at day 2 post inoculation (PI) till day 7 PI. Two Dutch and one German ARV derived from MAS causing the most severe intestinal lesions at day 2 PI, were further studied in the second trial using SPF broilers. These reoviruses did not cause weight gain depression in the broilers although lesions in the small intestine were present from day 1 up to day 4 PI and were more severe than in the white leghorn chickens. In one of the inoculated groups apical denuded villi were already present at day 1 PI. At day 7 PI the small intestine of the infected broilers appeared to be normal. Reovirus antigen was detected in the cytoplasm of the enterocytes at the tip and middle section of the affected villi both in layers and in broilers. To study the role of intestinal CD4+ and CD8+ T-cells and macrophages/monocytes in the pathogenesis of ARV, the numbers of these cells of the jejunal villi of one infected and the control broiler groups were compared. CD4+ T-cells were detected in low numbers and only in the infected broiler group at day 14 PI. The numbers of CD8+ T-cells and macrophages/monocytes were significantly higher in the infected broiler group than in the control broiler group at day 7 and 14 PI and at day 7 PI respectively. Our study indicates that the reovirus alone cannot induce intestinal lesions as found in MAS chickens. Moreover, CD8+ T-cells may play a major role in the pathogenesis and or reovirus clearance in the small intestine.     

Demonstration of IgA-containing cells in the small intestine of lambs infected with Nematodirus battus

A peroxidase anti-peroxidase immunohistochemical technique was used to demonstrate IgA-containing cells in the small intestine of lambs infected with Nematodirus battus. These cells were more numerous in the infected lambs than in the uninfected animals. The difference was greatest for the first three sites, 1 to 3 m distal to the pylorus, where the preponderance of the N battus infection is found. It is suggested that future immunohistochemical studies on the relationships between IgA and resistance to N battus should be directed to this area.     

人工感染堆型艾美耳球虫的雏鸡小肠病理学观察

本试验利用常规病理学方法,对人工感染5×104个堆型艾美耳球虫卵囊的雏鸡,在感染该球虫后7 d,即在堆型艾美耳球虫的一个生理周期内,对雏鸡的病理变化进行观察。眼观所见主要病理变化为小肠前段充血,肠壁变薄,苍白色,内容物含浆液量增多。病理组织学变化主要为小肠前段黏膜层有脱落,绒毛上皮细胞有变性、坏死、脱落,不同时期细胞内含有多量不同发育阶段的虫体。     

实验性流行性腹泻仔猪小肠粘膜上皮细胞及肠系膜淋巴结的超微结构

给8头生后3d的哺乳仔猪经口感染猪流行性腹泻病毒(PEDV)“吉”毒株,于感染后18、30、45和96h各扑杀2头,以透射电镜和扫描电镜观察了小肠粘膜上皮细胞及肠系膜淋巴结的超微结构。结果表明,小肠上皮细胞的病变因感染时间不同而有明显差异。上皮细胞的脱落和残留上皮细胞超微结构的破坏,以感染后30h最严重,病毒在这些上皮细胞内的增殖最显著。感染后45h,见有大量新生上皮细胞修补损伤的肠绒毛。感染后96h,小肠绒毛短缩、粗大乃至发生融合。实验仔猪肠系膜淋巴结内巨噬细胞和淋巴细胞的超微结构均遭到破坏,在巨噬细胞内见有PED冠状病毒粒子。     

Feline panleukopenia. II. The relationship of intestinal mucosal cell proliferation rates to viral infection and development of lesions.

Proliferation rates of small intestinal mucosal cells of noninfected germfree and specific pathogen-free kittens were compared to the incidence of infected cells and microscopic lesions in kittens experimentally infected with panleukopenia virus. Mucosal crypt length, cells per crypt, mitotic index and villous length were greater in specific pathogen-free kittens than in germfree kittens. Crypt cells per unit length and villous length per crypt length ratio were greater in germfree kittens. The cryptal cell proliferation rate of specific pathogen-free kittens was 2.24 times that of germfree kittens. Mucosal crypt length, cell per crypt and villous length were greater in the proximal jejunum than in the midjejunum of kittens within groups. Cell proliferation rates per crypt did not differ between areas of the intestine in kittens within groups. There were more virus-infected cells and lesions in specific pathogen-free kittens than in germfree kittens. The incidence of virus-infected cells and lesions was greater in the proximal jejumum and decreased along the small intestine.     

猪A群轮状病毒SCJY-13株的分离鉴定及致病性分析

【目的】 在从腹泻仔猪粪便中分离鉴定猪A群轮状病毒(Rotavirus group A, RVA)并了解其致病性。【方法】 应用MA-104细胞从仔猪腹泻粪便中分离鉴定RVA, 将其经口感染健康初生仔猪, 观察其临床症状, 并利用实时荧光定量PCR检测排毒、HE染色观察病理变化、免疫组织化学(immunohistochemistry, IHC)试验了解病毒分布。【结果】 分离到1株可引起MA-104细胞明显细胞病变的G9P[23] RVA, 命名为RVA/Pig-tc/CHN/SCJY-13/2017/G9P[23](简称SCJY-13株), 病毒滴度为10^5.5 TCID₅₀/100 μL。经口感染SCJY-13株的仔猪在感染后11 h出现腹泻, 持续到感染后165 h完全恢复, 其发病率为100%(7/7), 病死率为28.57%(2/7)。感染后8 h可从仔猪肛拭子检测到病毒核酸, 直至感染后192 h, 峰值出现在感染后24 h。感染后54 h各段小肠病毒载量达到最高, 其中回肠中病毒载量最高, 显著高于十二指肠、空肠(P<0.05);HE染色和IHC检测结果显示, SCJY-13在感染仔猪小肠的绒毛及隐窝中大量聚集, 尤其是回肠段; SCJY-13株感染引起十二指肠、空肠和回肠绒毛固有层大量淋巴细胞浸润、黏膜上皮细胞和肠绒毛尖端空泡变性、柱状细胞增多、绒毛断裂脱落等, 以回肠段较严重。【结论】 SCJY-13株能引起新生仔猪100%发病, 其主要靶位区在回肠, 感染后排毒时间长。本试验结果为猪RVA的致病性研究提供了一定的参考依据。     

A histopathologic,immunohistochemical, and ultrastructural study of the intestine in pigs inoculated with classical swine fever virus

The aim of this study was to report on the lesions occurring in the intestine during experimental classical swine fever (CSF) and to clarify the nature of infected cells and the distribution of viral antigen. Thirty-two pigs were inoculated with the virulent CSF virus (CSFV) isolate Alfort 187 and slaughtered from 2 to 15 postinoculation days; four animals of similar background served as a control group. Immunohistochemistry, electron microscopy, and the transferase-mediated deoxyuridine triphosphate nick-end labeling method were used to detect viral antigens and apoptosis. The results showed progressive lymphoid depletion and mucosal necrosis. The lymphoid depletion could have been caused by apoptosis of lymphocytes but could not be directly attributed to the effect of CSFV on these cells. Vascular changes, pathogenic bacteria, and viral infection of epithelial cells were ruled out as causes of necrotic lesions. However, large virally infected monocytes-macrophages with ultrastructural changes indicative of activation were observed in the intestine. This suggests that monocytes-macrophages play an important role in the pathogenesis of intestinal lesions. An understanding of the function of these cells will require additional study.     

Dehydrogenase activity in small intestine mucosa in experimental coccidiosis in suckling pigs]

The activities of 3-beta-hydroxybutyrate dehydrogenase (EC. 1.1.1.30.; HBD) and isocitrate dehydrogenase (EC. 1.1.1.41; ICD) were evaluated microdensitometrically in the mucosa of duodenum, jejunum and ileum of 19 conventional piglets infected on the first day after parturition (DAP) with oocysts of Eimeria debliecki coccidium (infection dose of 200,000 oocysts). The two investigated enzymes are deposited in mitochondria which are dispersed in the supra-, para- and infranuclear region of absorption cells (Fig. 1). The synthesis of the two dehydrogenases was investigated in the small intestine mucosa in the period of 1st to 10th day after infection (DAI). The HBD and ICD activities were also followed in the small intestine of four control conventional piglets at the age of 2-5 days (Tab. I). The two dehydrogenases could be characterized by a topographic gradient; it means that their activity was increasing in the small intestine mucosa through duodenum in an aboral direction. The ICD activity is higher in the intestinal mucosa of healthy piglets (Figs. 2 and 3), where its topic concentration was more marked while the HBD activity is dispersed in enterocytes (Fig. 4). In infected piglets the density of the two enzymes was demonstrated to decrease already in the starting period of experimental infection, and it reaches the lowest values for the first time on DAI 5-6 (Fig. 5, Tab. II), then on DAIs 9 (HBD; Fig. 6, graph 11)) or 8 (ICD, Fig. 7 and 10). In the period of experimental infection no statistically significant predisposition to the hypoactivity of target dehydrogenases nor its marked shift were observed. Somewhat rapid resumption of synthesis was demonstrated as soon as on DAI 8 in ICD (Fig. 8); its activity on DAI 10 in the intestinal mucosa corresponded to the 93% activity of this dehydrogenase recorded in the small intestine of control piglets. The density of HBD to the same day (DAI 10) reached in the intestinal mucosa of infected piglets the values making only 44.7% of those demonstrated in the intestinal mucosa of the control group of animals.     

A Case of Viral Neonatal Calf Diarrhea in a Québec Dairy Herd

This report is concerned with a consistent problem of neonatal calf diarrhea (NCD) in a dairy herd in which, for nearly two years, the morbidity had approached 100% and the mortality had varied from 20% to 45%. Generally, diarrhea appeared at three days of age. By the fluorescent antibody tissue section technique the two Nebraska NCD viruses (reo-like and corona-like) were detected in the cytoplasm of many absorptive cells of the small intestine from a calf submitted for necropsy. Reo-like virus antigen was not detected in the absorptive and crypt cells of the colon but coronavirus-like antigen was. An adenovirus was also isolated from the small intestine of this calf. The disease was reproduced experimentally in a two day old colostrum deprived calf with a bacteria free intestinal homogenate obtained from the naturally infected calf. Both Nebraska NCD viruses were demonstrated in this experimental animal. However, the adenovirus was not re-isolated. Histological lesions observed in the small and large intestines of the naturally and experimentally infected calves were similar and because of their good correlation with the immunofluorescent findings, a combination of the two Nebraska NCD viruses was thought to be a major cause of the neonatal calf diarrhea problem afflicting this dairy herd.     

Lesions of gnotobiotic calves experimentally infected with a calicivirus-like (Newbury) agent

Fourteen gnotobiotic calves were killed 0.5 to ten days after infection with Newbury agent SRV-1 and the changes in small intestinal structure and function were assessed, qualitatively and quantitatively, by light microscopy, scanning and transmission electron microscopy, enzymology and xylose absorption. The first enterocytes detected as infected by immunoperoxidase were those on the sides of villi at the base. Subsequently exfoliation of degenerate enterocytes resulted in stunted villi; mucosal beta-galactosidase activity fell and there was xylose malabsorption. Small intestinal damage, first detected at 12 hours after infection but almost repaired by ten days, was restricted to the anterior half of the small intestine. In the distal small intestine, where no virus-induced damage occurred, villi lengthened--possibly due to increased mitosis of crypt cells stimulated by enteroglucagon release.     

Enteric campylobacter infection in gnotobiotic calves and lambs

Gnotobiotic calves and lambs were infected orally with Campylobacter jejuni, C coli or C hyointestinalis to assess pathogenicity. All animals were successfully colonised and excreted mucoid faeces but showed no other clinical signs. Campylobacters colonised the large intestine better than the small intestine, in which bacterial numbers decreased with time after infection. Campylobacters were found occasionally in the lumen of crypts in close proximity to epithelial cells and included in a mucus-like material. Lesions were mostly in the large intestine in calves whereas in lambs they were present in the ileum. In animals inoculated with C jejuni or C coli scattered crypt abscesses, focal inflammatory infiltrates in the lamina propria and goblet cell discharge were found. In lambs inoculated with C hyointestinalis only minor changes were found in the small intestine. Serum antibody response was either absent or present at a low level only from the 19th day after infection.     

Immunohistochemical detection of porcine rotavirus using immunogold silver staining (IGSS).

Immunogold silver staining (IGSS) was applied for the detection of porcine group A rotavirus in formalin-fixed paraffin-embedded tissue sections of small intestine. Prior to the application of IGSS, the reactivity of protein A-gold as a marker was tested with group-specific antiserum in immunogold electron microscopy. Immune aggregates were intensely and specifically labeled with the gold complex. Application of IGSS to tissue sections resulted in specific dark staining of villous enterocytes infected by group A rotavirus. This method also proved effective for the detection of rotaviral antigen in infected cultured cells. The IGSS method may be suitable for routine diagnostic detection of rotaviral infections and may have application for detection of other viral pathogens of veterinary importance.     

贝氏莫尼茨绦虫感染绵羊对小肠局部黏膜淋巴组织的影响

为了研究贝氏莫尼茨绦虫自然感染绵羊对小肠黏膜免疫组织的影响,分别从宏观、微观及亚微观水平对自然感染贝氏莫尼茨绦虫的成年绵羊(感染组)肠道进行了细致地观察,并与正常成年绵羊(正常组)进行了比较.结果显示,感染组肠道所见虫体平均长度为1.5m,头节主要吸附在空肠淋巴集结分布丰富的部位,一般寄生数量为1～2条.眼观,虫体寄生部位黏膜增厚,表面有大量灰白色黏液附着,其间可见点状出血.镜下,局部黏膜上皮脱落,而在完整的黏膜上皮处,其上皮细胞、上皮内淋巴细胞、杯状细胞的数量都明显增多;固有层内毛细血管充血,淋巴细胞、浆细胞、弥散淋巴组织以及肠腺杯状细胞均有不同程度的增生,头节寄生处部分肠腺坏死;黏膜下层淋巴小结、淋巴集结显著增生,部分增生凸入固有层形成新的圆顶区;固有层与黏膜下层以及黏膜肌层可见大量嗜酸性粒细胞浸润.扫描电镜下,感染组肠黏膜上皮脱落;贝氏莫尼茨绦虫头节呈椭球状,有4个吸盘,无顶突,小沟,表面覆盖一层致密的微绒毛.研究结果表明,肠黏膜增厚,主要是局部黏膜免疫相关细胞在寄生虫虫体表面覆盖的微绒毛的不断刺激下,机体抗感染自身组织增生所致.成年绵羊对抗贝氏莫尼茨绦虫的感染可能是通过黏膜免疫相关组织增生来加强局部免疫力而实现的.     

Detection of Echinococcus multilocularis in foxes: evaluation of a protocol of the intestinal scraping technique

The intestinal scraping technique (IST) is widely used for the detection of definitive hosts infected with Echinococcus multilocularis. The sensitivity of the method has been questioned in recent years. Several variations of the technique are used that may differ in their performance. We therefore estimated the diagnostic sensitivity and specificity of the IST protocol used in our lab by examining the small intestines of 210 E. multilocularis-infected foxes and 294 foxes that had tested negative for this parasite. To this end, IST was first performed on 48 and 294 intestines from infected and uninfected foxes respectively, followed by an examination of the entire remaining mucosa of the small intestine to discover any infections with E. multilocularis that had not been detected by IST. The point estimate for diagnostic sensitivity was 100%. Five different classes of infection intensities were formed. The lower limits of the 95% confidence intervals ranged between 76.8% and 92.6% depending on the number of samples analysed per class. When the small intestines of another 162 infected foxes were examined by IST and the results recorded separately for the anterior, middle and posterior third of the small intestine, a strong preference of E. multilocularis for the posterior third was observed. For epidemiological purposes, it may thus be possible to restrict routine investigations to the posterior portion of the small intestine. By contrast, a reduction of the number of slides examined per infected animal may lead to a considerable loss in sensitivity in animals with a low intensity of infection.