Intestinal permeability to macromolecules in piglets infected with transmissible gastroenteritis virus

The permeability of the intestine of specific pathogen free piglets was investigated by measuring the concentration of 125-I in the blood after oral administration of 125-I polyvinylpyrrolidone (125-I PVP, MW=40 000 Da) and the concentration of 131-I in the faeces after intravenous administration of 131-I porcine albumin (131-I PA, MW=68 000 Da). The tests were performed one day before and up to two days after the piglets were infected with the Miller strain of transmissible gastroenteritis (TGE) virus. Biopsies of the jejunum were taken at the end of the experiment and blood samples were taken six-hourly. The piglets became anorexic and had diarrhoea 12 hours after infection; the packed cell volume decreased and the concentrations of urea and total serum proteins increased slightly after infection. However, the marked villous atrophy was not accompanied by an increased permeability of the intestine to PVP or PA.     

Transmission of Actinobacillus pleuropneumoniae among weaned piglets on endemically infected farms

Clinical outbreaks due to Actinobacillus pleuropneumoniae occur recurrently, despite the wide-scale use of antimicrobials or vaccination. Therefore, new approaches for the prevention and control of these outbreaks are necessary. For the development of alternative measures, more insight into the transmission of the bacterium on farms is necessary. The aim of this cohort study was to quantify transmission of A. pleuropneumoniae amongst weaned piglets on farms. We investigated three possible transmission routes: (i) indirect transmission by infected piglets within the same compartment, (ii) transmission by infected pigs in adjacent pens and (iii) transmission by direct contact within pens. Additionally, we evaluated the effect of independent litter characteristics on the probability of infection. Two farms participated in our study. Serum and tonsil brush samples were collected from sows pre-farrowing. Serum was analysed for antibodies against Apx toxins and Omp. Subsequently, tonsil brush samples were collected from all piglets from these dams (N = 542) in three cohorts, 3 days before weaning and 6 weeks later. Tonsil samples were analysed by qPCR for the presence of the apxIVA gene of A. pleuropneumoniae. Before weaning, 25% of the piglets tested positive; 6 weeks later 47% tested positive. Regression and stochastic transmission models were used to assess the contribution of each of the three transmission routes and to estimate transmission rates. Transmission between piglets in adjacent pens did not differ significantly from that between non-adjacent pens. The transmission rate across pens was estimated to be 0.0058 day⁻¹ (95% CI: 0.0030–0.010), whereas the transmission rate within pens was ten times higher 0.059 day⁻¹ (95% CI: 0.048–0.072). Subsequently, the effects of parity and serological response of the dam and litter age at weaning on the probability of infection of pigs were evaluated by including these into the regression model. A higher dam ApxII antibody level was associated with a lower probability of infection of the pig after weaning; age at weaning was associated with a higher probability of infection of the pig after weaning. Finally, transmission rate estimates were used in a scenario study in which the litters within a compartment were mixed across pens at weaning instead of raising litter mates together in a pen. The results showed that the proportion of infected piglets increased to 69% if litters were mixed at weaning, indicating that farm management measures may affect spread of A. pleuropneumoniae.     

Influence of Trypanosoma evansi in blood, plasma, and brain cholinesterase of experimentally infected cats

Changes in blood, plasma and brain cholinesterase activities in Trypanosoma evansi-infected cats were investigated. Seven animals were infected with 10⁸ trypomastigote forms each and six were used as control. Animals were monitored for 56 days by examining daily blood smears. Blood samples were collected at days 28 and 56 post-inoculation to determine the activity of acetylcholinesterase (AChE) in blood and the activity of butyrylcholinesterase (BChE) in plasma. AChE was also evaluated in total brain. The activity of AChE in blood and brain, and the activity of BChE in plasma significantly reduced in the infected cats. Therefore, the infection by T. evansi influenced cholinesterases of felines indicating changes in the responses of the cholinergic system.     

Intestinal permeability to polyethylene glycol 4000 and porcine albumin in piglets infected with transmissible gastroenteritis virus

The intestinal permeability of specific pathogen free piglets has been studied by measuring the concentration of ¹⁴C in the blood after oral administration of ¹⁴C polyethylene glycol (¹⁴C PEG, MW=4000) and the concentration of ¹³¹I in the faeces after intraperitoneal administration of ¹³¹I porcine albumin (¹³¹I PA, MW=68 000). The tests were performed one day before and up to two days after the piglets were infected with transmissible gastroenteritis (TGE) virus.Jejunal biopsies were taken from two piglets before the experimental infection, from two piglets 12 h after the experimental infection and from five piglets at the end of the experiment, 46 h after infection. Blood samples were taken six-hourly and faecal samples several times.Some piglets vomited before diarrhoea and loss of appetite started at 14 h after infection; the packed cell volume decreased before but increased after infection. Morphological examination showed hyperregenerative villous atrophy at 46 h after infection.There was no increase in the permeation of ¹⁴C PEG but there was a significant increase in the flux of ¹³¹I PA from the blood to the gut lumen.     

Intestinal and serum antibody response in gnotobiotic piglets to oral immunization with Escherichia coli

The local and systemic immune response to a formolized E. coli oral vaccine was investigated in 13 gnotobiotic piglets. Beginning at ten days of age animals received a daily dose of 10¹⁰ or 10¹¹ bacteria, on ten consecutive days. Intestinal loop tests with one animal of each group on day 26 showed protection which was more pronounced in the animal dosed 10¹⁰ bacteria compared with the other immunized piglet. Immunoglobulin class-specific antibodies to O and K antigens were determined by ELISA technique. In serum no IgG or IgA antibodies were found, whereas IgM-anti O149 antibodies in both immunized groups reached their highest level at day 4 of dosing and decreased thereafter. IgM-anti K88 antibodies were first detected at day 10 of dosing. Both immunized groups had comparable serum levels at days 20 and 30. Also in gut secretion the IgM antibody response was predominant, and higher levels were found in the 10¹⁰ group than in the 10¹¹ group. IgG and IgA antibody response were also detected in secretion.     

Intestinal absorption and structure in iron deficient piglets

The pattern of faecal egg counts after infection with 10,000 Haemonchus contortus larvae was similar within but not between, four pairs of monozygous twin sheep. Transfer of whole lymph or washed lymph cells from three immune donor sheep to their identical co-twin recipients reduced the susceptibility of the recipients to challenge with 10,000 larvae as measured by faecal egg counts. Cells from a nonimmune donor did not have this effect. In a final experiment, washed cells from an immune triplet sheep, which was actively responding to a repeated challenge infection, transferred a secondary local IgA response to a second recipient triplet and resulted in a marked reduction in worm count when compared with that of a third infectivity control triplet.     

高致病性猪繁殖与呼吸综合征病毒感染仔猪外周血细胞的动态变化

目的是通过检测HP-PRRS仔猪外周血细胞数量,探讨HP-PRRSV致病机制。方法是以HuN4株感染60日龄长白仔猪,应用分子生物学技术、全自动血液分析仪,对感染PRRSV仔猪外周血病毒载量、血细胞数量进行检测。结果显示PRRSV感染仔猪外周血病毒载量超过103copies/mL,WBC显著下降(P<0.05),RBC、HGB、HCT表现出周期性减少和增多(P<0.05),PLT显著下降(P<0.05);相关性分析表明,PRRSV载量对数值与WBC、PLT呈现中度负相关(0.40相似文献   

Evaluation of spray dried animal plasma and calcium formate as alternatives to colistin in piglets experimentally infected with Escherichia coli K99

Two trials were conducted to evaluate spray dried animal plasma and calcium formate as alternatives to preventive medication with colistin in piglets experimentally challenged with Escherichia coli K99. Two groups of newly weaned pigs were offered four treatments consisting of: Negative Control (NC); spray dried animal plasma (SDAP); calcium formate (CF) and colistin (COL). All animals were experimentally challenged with a single oral dose of E. coli K99. Their performance was recorded and, in the second trial, 6 piglets from each treatment were killed to obtain samples of jejunal mucosa for histological measurements and digesta from the ileum and the caecum for microbiological determinations. SDAP improved weight gain (P < 0.05) and feed intake (P < 0.06) in the first two weeks after weaning of trial 1, and a similar response, although not statistically significant, was found in trial 2. Colistin also resulted in a numerical improvement in performance, but calcium formate did not. No clear effects on mucosal histology were observed and only colistin had a significant effect on the microbiological composition of digesta.     

Effects of synbiotic-based Bifidobacterium animalis in female rats experimentally infected with Toxoplasma gondii

The aim of this study was to assess the effects of a synbiotic composed of Bifidobacterium animalis and fructooligosaccharides on female rats infected with Toxoplasma gondii. Female Wistar rats, treated or not with dexamethasone, were daily supplemented with synbiotics for 21 days. After 15 days of supplementation, the rats were orally infected with 10⁴T. gondii bradyzoites. Blood samples were collected to measure the levels of IFN-γ, IL-10 and T. gondii antibodies. All synbiotic-supplemented rats survived until the end of the experiment; however, non-supplemented dexamethasone-treated rats died between the fifth and the eighth days after T. gondii infection. Dexamethasone-treated rats supplemented with synbiotics (P < 0.05) were capable of synthesizing IFN-γ, and this immunological response was essential to ensure their survival. In addition, brain cysts were found in one rat not supplemented with synbiotics. Results suggest that the synbiotic composed of B. animalis and fructooligosaccharides may be beneficial to toxoplasmosis control.     

Immunological and pathological reactions in piglets experimentally infected with Mycoplasma hyopneumoniae and/or Mycoplasma flocculare.

The aim of this work was to examine in vivo whether infection with Mycoplasma hyopneumoniae (M. hyop) and/or Mycoplasma flocculare (M. floc) would interact and influence the severity of enzootic pneumonia in piglets. Specific pathogen-free, hysterectomy-derived piglets were allocated to six groups and experimentally inoculated with M. hyop. and/or M. floc at the age of 2 or 8 weeks. Clinical symptoms, frequency of coughing and temperature measurement were noted daily. Lung lesions were recorded by post-mortem examination and histological observations. The cross-inoculation with both mycoplasmas did not influence the clinical or the pathological picture of the disease. Evolution of specific and crossreacting antibodies was analyzed by ELISA and immunoblotting. Animals inoculated with M. floc did not develop any lesions but showed a weak antibody response 6-8 weeks post-infection (p.i.). No cross-reacting antibodies against M. hyop proteins were detected. In animals inoculated with M. hyop, the first antibody response was detectable 4-5 weeks p.i. and was stronger in piglets infected at the age of 2 weeks than at the age of 8 weeks. Three cross-reacting antibodies against M. floc proteins with molecular weights of 110, 47 and 33 kDa were detected by antibodies to M. hyop. Experimental infections with both mycoplasmas did not show differences in the pattern of species-specific proteins.     

仔猪肠道免疫与肠道健康

肠道黏膜免疫系统是仔猪体内最大的黏膜免疫器官,在识别和清除有害物质的过程中发挥着重要作用,同时能够对营养物质和肠道益生菌形成免疫耐受,与仔猪的健康关系最为密切。随着养殖业进入全面减抗、限抗的时代,养猪业面临巨大的挑战。仔猪肠道健康决定了猪场的生产效益,正确认识仔猪肠道免疫系统,科学调节肠道免疫,提高仔猪抗病能力,是决定养猪生产能否成功的重要因素。     

Depression of productivity in sheep infected with Fasciola hepatica

The productivity of 24 Corriedale weaner wethers in eight groups of 3, artificially infected with a range of fluke burdens, was studied by measuring body weight change, midside patch wool growth, fleece weights and feed digestibility over a period of 24 weeks.Data from bodyweight and patch wool measurement and feed digestibility were analysed by regression procedures. All parasitised groups exhibited a reduction in growth rate, patch wool growth and fleece weight, when compared with the control groups. Reduction in feed conversion efficiency was detected in groups having mean burdens of 45, 67 and 117 flukes. Because groups with mean burdens of 230 or more flukes had reduced feed intake, and sheep in these groups died, the feed conversion information from these groups cannot be considered unequivocal.The group mean liveweight changes, patch wool growth and fleece weights were closely related to the mean number of flukes in the respective group. Prediction equations for wool growth rate and body weight gain in fluke infected sheep are presented.     

Life cycle of Isospora suis in gnotobiotic and conventionalized piglets

Isospora suis had 3 asexual and 1 sexual intra-intestinal conventional life cycle. The first asexual generation was most prominent at 2 days p.i. (post inoculation) and produced 2–7 merozoites. The second-generation meronts were prevalent at 3–4 days p.i. and produced 2–12 large merozoites. At 4–5 days p.i. the third generation meronts were prominent and produced 4–24 small crescent shaped merozoites. Mature sexual stages were most prominent at 5–6 days p.i. The stages were most numeroous in the distal half of the small intestine. At 8–9 days p.i. stages morphologically similar to the second generation of meronts reappeared, followed by the further development into third generation merozoites and sexual stages. This was reflected in a prepatent period of 5 days and a biphasic patent period of 5–8 or 9, and 11–14 days p.i.Intraperitoneal injection of liver/spleen and intestinal lymph node homogenates, respectively, from piglets infected 24 and 48 h, previously with high doses of oocysts, resulted in a patent infection 10–12 days post inoculation of the donor piglets. No differences in the life cycle of I. suis were observed between conventionalized and germ-free piglets. An extra-intestinal life cycle of I. suis related to the second patent period was postulated.     

Preferential infection sites of Cysticercus bovis in cattle experimentally infected with Taenia saginata eggs

The preferential sites of infection of Cysticercus bovis were evaluated in the skeletal muscle and entrails of 25 cattle that were experimentally infected with Taenia saginata (2 × 10⁴ eggs). Two other animals were not inoculated (control). Ninety days after inoculation, all the cattle were euthanized. The carcasses were deboned and dissected into 26 anatomical sections (masseter muscles, brain, tongue, esophagus, heart, diaphragm, lungs, liver, kidneys, spleen, top sirloin butt, bottom sirloin butt, outside round, top (inside) round, transversus abdominus, top sirloin cap, strip loin, full tenderloin, eye of round, knuckle, shoulder clod, foreshank, shank, chuck, back ribs, and tail muscles). The dissected tissues were sliced into 5 mm sections. From the 25 cattle, 9258 C. bovis (cysticerci) were recovered; 75.02% (6946) of these were recovered from skeletal muscles and 24.98% (2312) from the entrails. A high parasitism level was found in the shoulder clod (12.55%), heart (11.02%), liver (9.48%), masseter muscles (8.51%), chuck (8.25%), strip loin and full tenderloin (7.26%), knuckle (6.63%), and back ribs (5.53%), totaling 69.23% (5738) of all of the detected cysticerci. On the other hand, there was a low C. bovis parasitism level in the brain, spleen, tail muscles, kidneys, esophagus, and diaphragm, representing just 3.9% of the total number of cysticerci. Given these results, we conclude that specific skeletal musculature regions, such as the shoulder blade, chuck, strip loin and full tenderloin, knuckle, back ribs and top round, which are not officially examined in many countries, are effective sites to efficiently screen C. bovis infection. To date, these regions have not been considered as preferential sites of C. bovis infection. Based on our work, however, these regions deserve greater attention from health inspectors because they contained a greater number of Cysticercus than the other regions of carcasses that are parasitized by T. saginata larvae.     

Intestinal permeability to macromolecules during colibacillosis in piglets

Intestinnal macromolecular permeability to macromolecules was determined in a group of specific pathogen free piglets before and after they were infected experimentally with Escherichia coli. Six hours after the infection all piglets developed a profuse diarrhoea. The urea and total protein concentrations in the serum increased markedly after the onset of diarrhoea. Haemoglobin concentration and PCV decreased steadily during the experiment but blood glucose concentration and lipid composition of the faeces did not change. No structural abnormalities in the jejunal and ileal mucosa were seen. No uptake of macromolecules (40 000 KDa) was found suggesting that molecules with a molecular weight of 40 000 or more do not play a role in the persistent diarrhoea sometimes seen in piglets after colibacillosis.     

断奶仔猪肠道健康与免疫调控

断奶应激一直是困扰现代养猪业的难题,由于幼龄仔猪消化系统和免疫系统都尚未发育成熟,早期断奶容易造成仔猪胃肠道功能紊乱,诱发仔猪断奶综合征。肠道是断奶仔猪消化食物、吸收营养的主要场所,也是体内最大的免疫器官之一。因此,通过研究仔猪肠道健康,阐明仔猪肠道生理结构及功能的发育规律,分析仔猪断奶前后肠道免疫调控特点,为不同日龄断奶仔猪确定合理的营养对策具有十分重要的意义,文章就近年来国内外仔猪肠道生理及免疫调控的研究进展进行综述。     

仔猪实验性感染新疆猪瘟病毒野毒株的病理学观察

猪瘟 ( Hog cholera,HC)是由猪瘟病毒 ( HCV)引起猪的一种急性、热性、败血性、高度接触性传染病。猪是惟一在自然条件下对 HCV易感的动物 ,该病流行广泛、发病率和病死率高、危害极大 ,因而在国际兽疫局制定的《国际动物卫生法典》中 ,将它列为 A类 1 6种法定传染病之一 ,我国     

Antibody response of swine experimentally infected with Mycoplasma hyosynoviae

Antibody responses of swine inoculated intranasally with M. hyosynoviae were determined using complement-fixation, latex-agglutination, metabolic-inhibition, and mycoplasmacidal tests. The infected swine developed latex-agglutinating antibodies by 6 days postinoculation, complement-fixing and metabolic-inhibiting antibodies by 9–12 days, and mycoplasmacidal antibodies which were first detected from 12 days to 8 weeks postinoculation. Antibody titers persisted for as long as 6 months postinoculation. Complement-fixing and mycoplasmacidal antibodies were mainly IgG, and latex-agglutinating antibodies were IgM. Early metabolic-inhibiting antibodies were IgM while later antibodies were mainly IgG. None of the pigs had detectable complement-fixing antibodiies to Mycoplasma hyorhinis.