Post-hatching developmental changes in the ultrastructure of the duodenal absorptive epithelial cells in 1, 10 and 60-d-old chickens, with special reference to mitochondria.

1. Post-hatching developmental changes in the ultrastructure, cell area and histological RNA content of duodenal absorptive epithelial cells were observed in 1, 10 and 60-d-old White Leghorn (WL) and broiler (BR) chickens, with special reference to the mitochondria (Mt). 2. Epithelial cells in 1-d-old WL and BR had a well-developed Golgi area and a dense cluster of rod type Mt near the cell surface and at the infranuclear region. In BR, cells included well developed profiles of endoplasmic reticulum but fewer supranuclear vacuoles than those of WL, in which numerous free ribosomes were also found. Some Mt in BR showed a bud-like protrusion from the main body (tadpole type Mt). These suggest that the fine structural maturation of the epithelial cells in WL is involved in the process of cell maturation but epithelial cells of BR have almost matured at hatching. 3. In 10-d-old WL and BR, supranuclear vacuoles had disappeared and Mt increased in number. In WL, in addition to a decrease in free ribosomes, Mt developed to the tadpole type and further to dumbbell type ones. In BR, Mt also aggregated at the perinuclear region and some of them had developed from dumbbell shapes to a thick doughnut type. These findings indicate that epithelial cells in both breeds are more developed ultrastructurally than those in 1-d-old and that epithelial cells in BR are more activated for digestive and absorptive functions than those in WL. 4. In 60-d-old WL and BR, Mt showed various types with thinner matrices than 10-d-old, suggesting that the cell structure and function had reached a stable state. 5. BR revealed higher values for cell area and RNA content than WL at every age and RNA content of both breeds were maximal at 10 d, followed by 60 d. 6. Mt changed their shapes from rod type to tadpole type. The latter then developed to doughnut type via dumbbell type, related to an increase of epithelial cell functions. 7. Epithelial cells of BR are thus more highly activated than WL cells at each age and reach morphological and physiological maturation around 10 d.     

Early epithelial invasion by Salmonella enterica serovar Typhimurium DT104 in the swine ileum

Salmonella enterica serovar Typhimurium is an important intestinal pathogen in swine. This study was performed to document the early cellular invasion of Salmonella serovar Typhimurium in swine ileum. Ileal gut-loops were surgically prepared in ten 4- to 5-week-old mixed-breed pigs and inoculated for 0-60 minutes. Loops were harvested and prepared for both scanning and transmission electron microscopy (SEM and TEM, respectively). Preferential bacterial adherence to microfold cells (M cells) was seen within 5 minutes, and by 10 minutes bacterial invasion of the apical membrane was seen in M cells, goblet cells, and enterocytes. This multicellular invasion was observed throughout the course of infection. In addition, SEM revealed a specific affinity of Salmonella serovar Typhimurium to sites of cell extrusion. Using TEM, bacteria in these areas were focused in the crevices formed by the extruding cell and the adjacent cells and in the cytoplasm immediately beneath the extruding cell. Our results suggest that early cellular invasion by Salmonella serovar Typhimurium is nonspecific and rapid in swine. Furthermore, the combination of SEM and TEM data suggests that Salmonella serovar Typhimurium may use sites of cell extrusion as an additional mechanism for early invasion.     

Ultrastructural study on the epithelial responses against attachment of indigenous bacteria to epithelial membranes in peyer's patches of rat small intestine

The ultrastructure of epithelial responses against the membrane adhesion of indigenous bacteria was investigated in the follicle-associated epithelium (FAE) of rat small intestine. The most frequent adherence of the various morphological types of bacteria to the epithelial membranes was found at the apex of the FAE. The attachment sites were deeply invaginated, and their bottoms were deformed into a sharp cone shape. Four layers with different electron densities were formed just beneath the apical membranes by microfilaments which surrounded the invaginations. The electron density of each layer was gradually decreased as being apart from the invaginations. The extremities of some bacteria in the invaginations were deformed into sharpened shapes. The cell walls of the extremities of the bacteria were occasionally dissolved in the invaginations, and their cytoplasms were slightly swollen with low electron densities. In some invaginations, the attached bacteria were eliminated to leave their fragments such as filamentous debris and a part of cell walls. Finally these remnants disappeared completely. When the bacterial colonies existed in the middle region of the FAE, the attachment of bacteria resulted in the engulfment of bacteria by M cells. The degenerated bacteria whose cytoplasmic matrices were separated into high electron dense materials and cleared materials were occasionally engulfed by ordinary microvillous columnar epithelial cells or goblet cells throughout the FAE. These findings suggest that the epithelial cells reject the attachment of live indigenous bacteria and that the M cells absorb indigenous bacteria in rat Peyer's patches.     

Attachment of different Escherichia coli strains to cultured rumen epithelial cells

The attachment to fully characterized primary rumen epithelial cell cultures of Escherichia coli strains isolated from different animal species and expressing F1–F4 or F17 fimbriae was examined. As the cell cultures contained stratified (keratinized) and non-stratified (non-keratinized) cells which grew either confluently or non-confluently, the strength of attachment of the different bacterial strains was assessed in relation to the differentiation state of the cells. Thus, strains having F1 fimbriae attached to all types of cultured cells, while strains with F2 and F3 fimbriae did not bind at all. E. coli strains having F4 or F17 fimbrae attached only to non-keratinized cells, particularly to confluent areas. As membrane glycosylation is known to change with differentiation (keratinization), our results suggest that the attachment of fimbriated E. coli strains which were capable of binding to rumen cells was more likely to be dependent on differentiation than the host specificity of the bacteria.     

Scanning electron microscopic observations on the intestinal villi in growing White Leghorn and broiler chickens from 1 to 30 days of age

1. To obtain intestinal morphological data demonstrating the faster growth rate in broiler (BR) than in White Leghorn (WL) chickens, villi of the duodenum, jejunum and ileum were examined from 1 to 30 d of age by scanning electron microscopy. 2. At the first day after hatching, villi of each intestinal segment showed a finger-like shape in both breeds. Villi developed to a plate-like shape in the duodenum, a wave-like shape in the jejunum and a tongue-like shape in the ileum at 30 d of age via the common plate-like villi at 10 d of age. The fundamental villous shape and arrangement seem to be accomplished by 10 d of age; two types of obliquely elongated plate-like villi showed a zigzag arrangement, adjoining at an angle of 40 degrees to 60 degrees like an oblique T-shape. It is suggested that such a villous arrangement would be more effective for nutrient absorption by inducing a long zigzag flow of ingesta. 3. Compared with WL, even at the first day after hatching BR had many more developed epithelial cell protrusions over the whole apical surface of the duodenal villi. In WL the protrusions were not so apparent and located only in the central area of the villous tip. Furthermore, at 10 d of age BR showed more developed and larger villi, many wider microvilli at the apical portion of villi and more active extrusions of epithelial cells from the tip of the duodenal and jejunal villi. 4. These morphological characteristics of villi in early life in BR suggest a greater absorptive surface area and a more active intestinal function, permitting the faster growth rate of BR immediately after hatching.     

Effect of hypothalamic electrolytic lesions in White Leghorn and broiler male cockerels

1. This study compared the effect of bilateral electrolytic lesions of the basomedial hypothalamus (HL) in broiler and White Leghorn (WL) males. 2. Hypothalamic lesions were placed in WL at 10 weeks of age (body weight 1.1 kg) and in broilers, either at 6 weeks (body weight 1.5kg) or at 10 weeks of age (body weight 3.4kg). They were fed ad libitum until autopsy at 16 and 17 weeks of age for broilers and WL, respectively. 3. Hypothalamic lesions caused obesity (high percentage weight of abdominal adipose tissue) in both strains. Obese fowls with unimpaired reproductive systems were classified as OB and those with functional castration as FC (functionally castrated) or FCLC (functionally castrated with large comb). 4. All post-HL syndromes-OB, FC and FCLC-were present in WL, whereas all obese broilers (which are immature at this age) were classified as OB. 5. The percentage weight of abdominal adipose tissue in OB broilers was lower than in OB WL (3% vs 5%, respectively). 6. Daily food intake of OB broilers was higher than control at 12 to 15 weeks of age, regardless of time of placement of HL, whereas daily food intake of OB WL was significantly higher than that of control WL only during the first 2 weeks following HL. 7. Body weight of OB broilers at autopsy was 20% higher than control broilers, whereas body weight of OB WL was not significantly affected. 8. An additional group of broilers was reared to sexual maturity under food restriction until 28 weeks of age. HL were placed at 10 weeks of age (body weight 1.7 kg). Autopsy was performed after a 4-week period of ad libitum feeding. 9. There were OB as well as FC and FCLC among the HL, food-restricted broilers. Percentage weight of testes and spleen were reduced in OB fowls of both strains, but more so in OB WL. 10. Hyperphagia and weight gain were not observed during the ad libitum feeding period of those obese broilers after HL, indicating that hyperphagia and weight gain are secondary to obesity.     

单色光对肉鸡免疫功能的影响

选用260只刚出壳AA肉鸡公雏,随机分为红（660 nm）、绿（560 nm）、蓝（480 nm）和白（400-700 nm）4个光色处理组,分别用4种发光二级管作为光源进行处理。每个处理设5个重复,每个重复13只鸡,人工光照光强度均为15 lx,光照时间为23 h,试验期为7周。49日龄测定肉鸡脾脏的质量,21和49日龄测定外周血T淋巴细胞转化率和血清皮质醇水平,14、28、42和49日龄测定新城疫（NDV）抗体滴度。结果表明：与红光组比较,蓝光组49日龄肉鸡脾脏的质量提高42.2%（P〈0.05）,而白光、绿光和蓝光各组间差异不显著（P〉0.05）。与白光组相比,蓝光组21和49日龄皮质醇水平分别降低25.2%和26.2%（P〈0.05）。与红光组比较,28日龄时绿光组的新城疫抗体水平显著高32.9%（P〈0.05）,而白光、红光和蓝光各组间差异不显著（P〉0.05）;49日龄时蓝光组NDV的抗体水平显著高62.8%（P〈0.05）,但蓝光、绿光和白光组间差异不显著（P〉0.05）。与红光组比较,21日龄时白光和绿光组肉鸡外周血T淋巴细胞的转化率均显著提高（分别为107.1%和80.8%,P〈0.05）,49日龄时白光和蓝光组分别显著提高41.5%和26.9%（P〈0.05）。上述结果表明,在15 lx光强度下,肉鸡生长前期选用绿光照明,后期改为蓝光照明,可以提高肉鸡免疫功能,而且在一定程度上蓝光还有缓解免疫应激的作用。     

甘露寡糖对肉鸡生长性能及肠黏膜形态的影响

选择120只1日龄肉鸡随机分为2组,试验组添加0.3%的甘露寡糖。每组6个重复,每个重复10只。每组基础日粮相同。试验结果表明:试验后期(4~5周龄)和整个试验期(0~5周龄)的增重,添加0.3%甘露寡糖组显著高于对照组(P<0.05),试验前期(0~3周龄)未见明显效果。试验前期的料肉比,添加0.3%甘露寡糖组显著低于对照组(P<0.05),试验后期和整个试验期处理组虽然均低于对照组,但无显著差异。添加0.3%甘露寡糖组回肠绒毛长度以及绒毛长度与隐窝深度之间的比值均显著高于对照组(P<0.05)。添加0.3%甘露寡糖可显著提高肉鸡的生长性能,并可以改善肠黏膜的形态,增大小肠吸收面积。     

Scanning and transmission electron microscopic observations on the host-parasite relationship in intestinal cryptosporidiosis of neonatal calves

The association of cryptosporidia with the intestinal epithelium of three neonatal calves was studied by scanning (SEM) and transmission (TEM) electron microscopy. Trophozoites and schizonts were observed embedded in the microvillous brush border of epithelial cells. Merozoites, released from schizonts, were seen free in the lumen and penetrating epithelial cells by SEM and TEM. Incorporation of microvilli into the parasitophorous envelope of trophozoites was seen by TEM. These findings indicate that cryptosporidia develop at an intracellular position in the apex of the epithelial cells following merozoite penetration.     

1～21日龄雌性肉仔鸡表观回肠可消化色氨酸需要量评定

本试验旨在研究1～21日龄雌性肉仔鸡表观回肠可消化色氨酸需要量及饲粮色氨酸水平对肉仔鸡肉品质、抗氧化指标和免疫指标的影响。试验选取480只1日龄雌性商品代肉雏鸡,随机分成5个处理,每个处理8个重复,每个重复12只鸡。采用含0.170%色氨酸的玉米-豆粕-玉米蛋白粉型基础饲粮,分别在其中添加0、0.021%、0.042%、0.063%和0.084%晶体L-色氨酸,使饲粮色氨酸水平分别为0.170%、0.191%、0.213%、0.234%和0.248%。测定1～21日龄肉仔鸡生产性能、胸肌品质、抗氧化指标、免疫指标和21～25日龄肉仔鸡氨基酸表观消化率和表观回肠消化率。结果表明:饲粮色氨酸水平显著影响1～21日龄肉仔鸡采食量及增重(P<0.05),采食量及增重与饲粮表观回肠可消化色氨酸水平呈现二次曲线关系(P<0.05)。1～21日龄肉仔鸡获得最大增重的饲粮表观回肠可消化色氨酸水平为0.176%,表观回肠可消化色氨酸摄入量为68.15 mg/d。与饲粮色氨酸水平0.170%相比,饲粮色氨酸水平0.213%及0.248%可显著降低肉仔鸡胸肌丙二醛含量、肝脏总超氧化物歧化酶活性和血清谷丙转氨酶活性(P<0.05),饲粮色氨酸水平0.248%可显著提高肉仔鸡屠宰后45 min胸肌pH、肠道总分泌型免疫球蛋白A浓度及血清总免疫球蛋白A浓度(P<0.05)。由此可知,1～21日龄雌性肉仔鸡获得最大增重的表观回肠可消化色氨酸需要量为0.176%(68.15 mg/d)。提高饲粮色氨酸水平可减轻肉仔鸡组织细胞脂质过氧化损伤,降低屠宰后肉仔鸡胸肌酸度,改善肉仔鸡肠道黏膜免疫和体液免疫能力。     

Polysaccharidase preparations added to a wheat-based diet: effects on performance and digestive parameters of broiler chickens held at three different locations

1. Three experiments of 39 d were simultaneously conducted to assess the efficacy of three carbohydrase combinations on performance, apparent nutrient digestibility, intestinal morphology and digestive organ relative weights of chickens fed on a wheat-based diet. 2. Experiment 1 was performed under laboratory conditions, with the birds housed in cages. In experiment 2, the birds were placed in floor pens built in a commercial farm, and raised with their contemporaries at the farm. In experiment 3, broilers were reared under industrial management circumstances in commercial farms. A two-phase feeding programme was used: starter from 1 to 21 d of age and finisher from 22 to 39 d. The basal diet without supplementation (BD) and three enzyme preparations (BDF, BDP and BDR) were evaluated. 3. No differences in growth traits were observed among treatments in experiments 1 and 2. 4. When overall growing period was evaluated, all enzyme combinations improved apparent DM ileal digestibility of feed in the three experiments, but significant differences were only found in experiments 2 and 3. For this same period, an increase in apparent CP ileal digestibility of broiler chickens fed supplemented diets against the control group was found in experiment 3. Moreover, a significant greater apparent ileal fat digestibility in the enzyme treatments compared with the control group was shown when broilers were raised under industrial conditions (experiment 3). 5. Enzyme combinations had no effect on villus heights and crypt depths of broilers in experiment 1, whereas, in experiment 2, a greater villus height was found in BDF and BDP treatments than in control birds. 6. There were no differences in digestive organ relative weights among dietary treatments except for pancreas in experiment 1.     

The Use of Specific Antibodies to Demonstrate the Glycocalyx and Spatial Relationships of a K99-, F41- Enterotoxigenic Strain of Escherichia coli Colonizing the Ileum of Colostrum-deprived Calves

Electron microscopy was used to study the interaction between the glycocalyx of enterotoxigenic Escherichia coli strain 210 (09:K30+;K99-;F41-:H-) and the glycocalyx of epithelial cells in then ileum of experimentally infected newborn colostrum-deprived calves. Fixation of tissues in anti-K30 antibody and ruthenium red was used to stabilize the bacterial glycocalyx so that the spatial relationship between the bacteria and the intestinal epithelial cells could be characterized.

When strain 210 was grown in vitro and reacted with anti-K30 antibody prior to staining with ruthenium red, the extensive glycocalyx could be clearly visualized surrounding the bacterial cells. By negative staining, an unidentified pilus was also seen. Sections of ileum from infected calves, which were not fixed in antibody nor stained with ruthenium red, revealed attached bacteria which were surrounded by an electron-translucent zone and no visible bacterial glycocalyx. When ruthenium red staining was used, the bacterial glycocalyx partially collapsed during the dehydration steps of fixation, but could be seen as either a fibrous capsule or an electron-dense accretion on the bacterial cell surface. When ileal tissue was reacted for one hour in anti-K30 antibody before staining with ruthenium red, the bacterial glycocalyx was seen as a discrete electron-dense structure up to 1.0µm thick which was in intimate contact with the glycocalyx of the epithelial cells. The importance of the bacterial exopolysaccharide to microcolony formation on the villi could be clearly visualized.

     

Leukocyte responses in two breeds of layer chicken that differ in susceptibility to induced amyloid arthropathy

Amyloid arthropathy in chicken can be induced by intravenous inoculation of an arthropathic and amyloidogenic Enterococcus faecalis in susceptible breeds. The commercial brown layer hybrids (BL) are more susceptible to the disease compared to their white counterparts (WL). The precursor of amyloid-A protein, which is serum amyloid-A (SAA), is identical in WL and BL. To investigate the factors involved in the breed-restricted susceptibility to amyloid arthropathy, we studied the type of leukocyte response and inflammatory reactions in E. faecalis-induced disease. In the BL, a significant dose dependent peripheral leukocytosis mainly by heterophils, and plasma cell infiltration in arthritic joints was found. In contrast, secondary lymphoid nodular aggregates in the synovial membrane were prominent in the WL. The aggregates consisted mainly of CD8+ T cells. The high number of circulating leukocyte and prolific plasma cell responses in the BL predict extensive humoral and acute phase reactions. This is in agreement with literature data on suppressed T-cell function in casein-induced amyloid-susceptible mice strains. The difference in leukocyte response and type of inflammation between WL and BL, when arthropathic and amyloidogenic bacteria induce infection, in conjunction with susceptibility to amyloid arthropathy, is discussed in view of the murine T-helper responses.     

Alteration in the apoptosis process of rat esophageal epithelium with hyperproliferation of indigenous bacteria under a physiological condition

The apoptosis process in rat esophageal epithelium was investigated using enzyme-immunohistochemistry and transmission electron microscopy. As a result, Fas and Fas-L were expressed in the epithelial cell membrane and cytoplasm from the stratum spinosum (SS) to the stratum granulosum (SG). No TNF-R1 show immunopositivity in the cell membranes. TNF-α and caspase-8 were not observed in any layer. Caspase-10, cleaved caspase-3, XIAP and DNase-1 were found in the epithelial cytoplasm from the SS to the SG, whereas Bid, Apaf-1 and cleaved caspase-9 were detected only in the SG. Cytochrome c was observed as cytoplasmic granular positivity from the stratum basale (SB) and altered into homogeneous immunopositivity in the SG. Bcl-2 and Bcl-X immunopositivity was detected in cytoplasm from the SB to the SG. Immunoreactions of Bak in the cytoplasm and Bax beneath the cell membrane were observed from the upper portion of the SS with increasing intensity toward the SG. In the sites with the hyperproliferation of indigenous bacteria, TNF-R1, TNF-α and caspase-8 were detected in the SG and the immunopositive intensities of Bid, Apaf-1 and cleaved caspase-9 were altered to be strong. Prominently swollen cells and decreased mitochondria were ultrastructurally confirmed in the uppermost layers of stratum corneum. These findings suggest that the Fas-Fas-L-interaction initially induces apoptosis through a mitochondria-independent pathway and secondarily through a mitochondria-dependent pathway, leading to eventual epithelial cell death in the rat esophageal epithelium. The bacterial stimuli probably enhance the mitochondria-dependent pathway through the TNF-R1-TNF-α interaction.     

鸡肾型IBV引起病理形态学的电镜观察

本试验通过扫描电镜与透电镜，观察了鸡肾型传生支气管炎病毒（ＩＢＶ）在气管、肺、肾人的分布以及对器官组织的损伤作用，观察结果表明，肾型ＩＢＶ主要分布于气管粘膜上皮、肺呼吸毛细管上皮和肾上管上皮细胞浆内，还分布于毛细血管周围。肾型ＩＢＶ对器官组织的损伤作用主要表现为：气管粘膜纤毛上皮细胞的纤毛脱落，有的缠结成簇，甚至严重倒伏。肺呼吸滤过膜增厚，并发生纤维化。肾小管质液化，线粒体变萎缩，有的线粒体溶解呈     

Adherence of Escherichia coli O157:H7 to epithelial cells in vitro and in pig gut loops is affected by bacterial culture conditions

The objectives of this study were to determine the effect of bacterial culture conditions on adherence of enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain 86-24 in vivo to pig enterocytes and to compare the results with adherence in vitro to cultured HEp-2 and IPEC-J2 cells. Growth of O157:H7 in MacConkey broth (MB) resulted in almost no adherence to both HEp-2 and IPEC-J2 cells; prior exposure of the bacteria to pH 2.5 reduced adherence. There was greater adherence by bacteria from static cultures than by those from shaken cultures and by bacteria cultured in brain-heart infusion (BHI) plus NaHCO? (BHIN) than by bacteria cultured in BHI. In contrast, in pig ileal loops, bacteria cultured in MB adhered well to enterocytes, and prior exposure to pH 2.5 had no effect on adherence. Among several media tested for their effect on bacterial adherence in the pig intestine, MB and BHIN proved to be the best. Bacterial adherence was dose-dependent and was more extensive in the ileum than in the colon. This study demonstrated that there are remarkable differences between culture conditions that promote adherence of an EHEC O157:H7 strain in vitro and in vivo, that culture conditions profoundly affect adherence to epithelial cells in vitro and in vivo, and that pig ileal loops are better suited to adherence studies than are colon loops.     

Direct fed microbial supplementation repartitions host energy to the immune system

Direct fed microbials and probiotics are used to promote health in livestock and poultry; however, their mechanism of action is still poorly understood. We previously reported that direct fed microbial supplementation in young broilers reduced ileal respiration without changing whole-body energy expenditure. The current studies were conducted to further investigate the effects of a direct fed microbial on energy metabolism in different tissues of broilers. One hundred ninety-two 1-d-old broiler chicks (16 chicks/pen) were randomly assigned to 2 dietary groups: standard control starter diet (CSD) and CSD plus direct fed microbial (DFMD; 0.3%) with 6 pens/treatment. Body weight, feed consumption, whole-body energy expenditure, organ mass, tissue respiration rates, and peripheral blood mononuclear cell (PBMC) ATP concentrations were measured to estimate changes in energy metabolism. No differences in whole body energy expenditure or BW gain were observed; however, decreased ileal O(2) respiration (P < 0.05) was measured in DFMD fed broilers. In contrast, the respiration rate of the thymus in those broilers was increased (P < 0.05). The PBMC from DFMD fed broilers had increased ATP concentrations and exhibited increased ATP turnover (P < 0.01). To determine if the increased energy consumption by PBMC corresponded with an altered immune response, broilers were immunized with sheep red blood cells (SRBC) and assayed for differences in their humoral response. The DFMD-fed broilers had a faster rate of antigen specific IgG production (P < 0.05) and an increase in total IgA (P < 0.05). Collectively, these data indicate that supplementation with the direct fed microbial used in this study resulted in energy re-partitioning to the immune system and an increase in antibody production independent of changes in whole body metabolism or growth performance.     

Interaction with pig ileal explants of Escherichia coli O45 isolates from swine with postweaning diarrhea.

We have previously observed that Escherichia coli O45 isolates from swine postweaning diarrhea (PWD) induced attaching-effacing (A/E) lesions in experimentally inoculated gnotobiotic piglets. In the present work, ileal explant culture has been used as an in vitro model for the study of the development of A/E lesions due to these isolates. The characteristic intimate bacterial attachment and microvilli effacement with cupping and pedestal formation, identical to that observed in gnotobiotic piglets, was demonstrated in pig ileal explants inoculated with O45 E. coli isolates. The initial attachment of bacteria to the enterocytes was observed from 2 to 4 h postinoculation (PI) and full development of A/E lesions was observed within 8 h PI. In this model, we observed that 22 of 25 eaeA-positive O45 isolates induced A/E lesions. However, A/E lesions were not observed for any of 7 eaeA-negative O45 isolates. Thus, we describe a useful in vitro model for the study of A/E capacity of porcine E. coli. Use of this model has enabled us to demonstrate the relatedness of the eaeA gene to A/E capability among porcine O45 E. coli from PWD.     

Quantity of virulent fowl adenovirus serotype 1 correlates with clinical signs,macroscopical and pathohistological lesions in gizzards following experimental induction of gizzard erosion in broilers

In the present study day-old specific-pathogen-free (SPF) and commercial broilers with maternally derived fowl adenovirus serotype 1 (FAdV-1) antibodies were orally infected with a European “pathogenic” FAdV-1, isolated from broilers showing signs of gizzard erosion. During the experiment, broilers were observed and weighed daily up to 17 days post infection (dpi). Clinically, both infected groups showed significant decrease of weight compared to respective negative control groups. Birds were examined by necropsy at 3, 7, 10, 14 and 17 dpi. Pathological changes in the gizzards were noticed in both experimentally infected groups from 7 dpi onwards. Macroscopically, erosion of the koilin layer and inflammation or ulceration of the gizzard mucosa were observed. Histologically, presence of FAdV-1 in intranuclear inclusion bodies of degenerated glandular epithelial cells was demonstrated by in-situ hybridization and inflammatory cell infiltration of the lamina propria, submucosa and muscle layer was detected. Tissue samples were investigated by a recently developed real-time PCR and the viral DNA load was calculated from gizzard, liver, spleen and cloacal swabs with the highest amounts of FAdV-1 DNA found in the gizzard. For the first time, successful reproduction of clinical signs in broilers as well as pathological lesions in the gizzard were achieved with a European FAdV-1 isolate displaying some genetic differences to so far reported virulent FAdV-1 from Japan. Furthermore, highest viral load in gizzards could be linked with macroscopical and histological lesions. Therefore, the conducted analyses provide important insights into the pathogenesis of adenoviral gizzard erosion.     

Bovine cryptosporidiosis: a transmission and scanning electron microscopic study of some stages in the life cycle and of the host-parasite relationship.

Transmission and scanning electron microscopy of the ileal mucosae from 12 calves infected with Cryptosporidium sp. showed cryptosporidia free in the lumen and attached to epithelium. The attached parasites were interpreted to be extracellular and adherent to the microvillous border of epithelial cells. Stages of the organism included crescentic-free merozoites, trophozoites, schizonts, gametes and oocysts. Attached parasites were detected chiefly at villous tips and all stages were present on a single villus. Attachment sites were characterized by absence or disintegration of microvilli, disorganization of the terminal web and development of a specialized attachment zone. There were increased numbers of lysosomes and irregularities in the nuclear membrane of parasitized epithelial cells. It was concluded that cryptosporidia exist in bovine intestine as extracellular parasites and cause epithelial changes that in turn probably cause or contribute to diarrheal disease.