Development of a hamster model of Chlamydophila pneumoniae infection

The aim of this study was to develop a new experimental model of Chlamydophila pneumoniae infection in the hamster. Intraperitoneal injection of C. pneumoniae purified elementary bodies (EBs) in the hamsters caused a systemic infection, since it was possible to isolate viable chlamydiae from several organs up to 14 days after infection. In particular, spleen infection was detectable up to 7 days post infection in 100% of animals. In contrast, cultures of the organs obtained from intranasally infected animals were far less frequently positive. Systemic infection probably occurred via macrophages, as demonstrated by the presence of intracellular chlamydial inclusions in peritoneal macrophages of peritoneally inoculated animals four days after infection. Furthermore, by infecting LLC-MK2 cells with supernatant preparations obtained from these macrophages, it was possible to observe the development of chlamydial intra-cytoplasmic inclusions after 96 h. Immunization of 18 hamsters with heat-inactivated purified EBs completely protected 16 animals and substantially reduced infection levels in the remaining two. Sera obtained from immunized hamsters prior to challenge reacted mainly against two C. pneumoniae proteins of about 60 kDa, when tested by immunoblot.     

Retrospective study on the outcomes and risk factors of right paramedian abomasopexy for right abomasal disorders in 47 dairy cows

Very few epidemiologic studies have verified the utility of the right paramedian abomasopexy (RPA) technique in cows with right abomasal disorders. This study aimed to investigate the outcomes and risk factors for non-survival in the herd within 30 days of surgery in cows with right abomasal disorders who underwent the RPA technique. Forty-seven Holstein cows with right abomasal disorders (25 with right abomasal displacement [RDA] and 22 with right abomasal volvulus [RAV]) were included. Twenty-two cows with RDA (22/25, 88.0%) and 10 cows with RAV (10/22, 45.5%) survived at 30 days post-surgery. Multivariate logistic regression analysis indicated that hyponatremia, hypokalemia, and the presence of abomasal volvulus were the major risk factors associated with non-survival.     

Reduced Activity of Lecithin:Cholesterol Acyltransferase in the Serum of Cows with Ketosis and Left Displacement of the Abomasum

Lecithin:cholesterol acyltransferase (LCAT) activity was evaluated in sera from cows with ketosis and in some with left displacement of the abomasum (LDA) that occurred during early lactation. The enzyme activities of 652±214 U (mean±SD) in cows with ketosis (n = 6) and 683±110 U in those with LDA (n = 5) were significantly (p<0.01) decreased compared to those in healthy normal cows (994±65 U, n = 8). Serum concentrations of free cholesterol, cholesteryl esters (CE) and phospholipids were similarly decreased in the two diseases. Cows whose LCAT activity and CE concentration were lower than the normal values were detected while in the non-lactating stage, and some of these cows had ketosis after parturition. It is suggested that evaluation of the LCAT activity and of the CE concentration during the non-lactating stage would be useful in detecting cows that are susceptible to postparturient disorders such as ketosis.     

奶牛真胃变位发病原因研究进展

奶牛真胃变位的发病原因可能与真胃壁中肠道神经元功能性紊乱有关,这对揭示奶牛真胃变位的发病机制有重要意义.真胃变位奶牛肠道神经元的一氧化氮合酶活性升高,乙酰胆碱敏感性降低,真胃的运动力减弱和排空机能受损可能与这种异常关系有关,即抑制肠道神经元的增强活性,皱胃肌肉的胆碱能神经敏感性降低.流行病学调查和试验研究已证实真胃迟缓和真胃扩张是奶牛真胃变位的主要原因,同时,品种、遗传背景、双胎、泌乳早期阶段(特别是第1周)富含高精料日粮而缺乏优质粗饲料、代谢紊乱性疾病(酮病、脂肪动员增加、胰岛素抗药性)和其他并发疾病(子宫内膜炎、乳房炎、蹄病)等都是真胃变位发生的诱发因素.     

Chlamydophila abortus infection in the mouse: a useful model of the ovine disease

Chlamydophila (C.) abortus is an obligate intracellular bacterium able to colonize the placenta of several species of mammals, which may induce abortion in the last third of pregnancy. The infection affects mainly small ruminants resulting in major economic losses in farming industries worldwide. Furthermore, its zoonotic risk has been reported in pregnant farmers or abattoir workers. Mouse models have been widely used to study both the pathology of the disease and the role of immune cells in controlling infection. Moreover, this animal experimental model has been considered a useful tool to evaluate new vaccine candidates and adjuvants that could prevent abortion and reduce fetal death. Future studies using these models will provide and reveal information about the precise mechanisms in the immune response against C. abortus and will increase the knowledge about poorly understood issues such as chlamydial persistence.     

Detection of Chlamydophila pneumoniae in cats with conjunctivitis

Objective To determine the presence of chlamydial species including recently described chlamydial agents as well as the human pathogen Chlamydophila pneumoniae in feline conjunctivitis. Animal studied Twenty five cats without and 49 cats with conjunctivitis were tested for chlamydia using a Chlamydiaceae real time (RT) PCR (targeting the 23S rRNA gene sequence), a Chlamydiales PCR (targeting the 16S rRNA gene sequence), and cell culture. The PCR products of all positive samples were sequenced and subsequently analyzed using a basic local alignment search tool search. Results Chlamydiaceae RT PCR and subsequent sequence analyses identified C. pneumoniae in five cats in the conjunctivitis group. The presence of Chlamydophila felis was shown in two cats with conjunctivitis. Chlamydiae related to uncultured members of Chlamydiales were detected in three conjunctivitis cases and in one cat without clinical symptoms. Conclusion This study detects for the first time, the known human pathogen C. pneumoniae in feline conjunctivitis cases using Chlamydiaceae RT PCR and sequence analyses.     

奶牛皱胃变位病因及发病机制研究进展

奶牛皱胃变位是指皱胃的正常解剖位置发生改变,导致消化机能障碍的内科疾病。此病多发于高产奶牛,造成了巨大的经济损失。论文通过对遗传、品种、胎次及生产水平、发病时期、营养和新陈代谢及环境等来综述奶牛皱胃变位的病因,从皱胃弛缓学说和机械因素学说两方面综述其发病机制研究进展,为该病的有效预防和控制提供理论基础。     

Alterations in Coagulation Profiles and Biochemical and Haematological Parameters in Cattle with Traumatic Reticuloperitonitis

This study was designed to investigate alterations in coagulation, and in biochemical and haematological parameters in cattle with traumatic reticuloperitonitis (TRP). In the study, 28 dairy cattle with TRP and 10 clinically healthy cattle (control) of different ages and breeds were used. Cattle with TRP had prolonged prothrombin time (PT), thrombin time (TT) and activated partial thromboplastin time (APTT). Erythrocytopenia, thrombocytopenia and hyperfibrinogenaemia were detected in animals with TRP. Furthermore, the serum concentrations of total protein, globulin and total bilirubin, and the activities of alkaline phosphatase (ALP) and aspartate aminotransferase (AST) were also high in cattle with TRP compared to those of the control group. The serum concentrations of calcium were significantly low in the TRP group. The results of this study, therefore, indicate that TRP causes significant coagulation abnormalities and biochemical and haematological alterations in dairy cattle.     

肺炎支原体感染大鼠实验模型的建立

本试验旨在建立肺炎支原体感染的Wistar大鼠模型 ,为研究肺炎支原体的发病机制及药物治疗理论提供基础。采用滴鼻法对实验大鼠进行肺炎支原体感染 ,利用PCR法进行咽拭子检测 ,并以透射电镜和光学显微镜进行肺部病理组织学检查。结果发现 ,实验大鼠在感染肺炎支原体 1 0d时 ,咽拭子PCR检测结果为阳性 ;透射电镜观察到肺脏细胞膜破裂 ,线粒体变性 ,嵴断裂 ;光镜下可见到支气管及肺血管周围有明显的淋巴细胞浸润 ,形成斑片状间质性支气管肺炎。结果表明了Wistar大鼠对肺炎支原体较易感 ,并产生以间质性肺炎为主要特征的肺部和呼吸道感染 ,也说明本次造模试验成功     

Macromineral status of dairy cows with concurrent left abomasal displacement and fatty liver

Abstract

AIM: To evaluate the macromineral status of field cases of dairy cows surgically treated for left abomasal displacement (LDA), with concurrent fatty liver of different severity, and compare this for animals that died or recovered.

METHODS: Sixty-eight Holstein dairy cows with LDA and 110 control cows, from 28 farms, were used in the study. Blood samples and liver biopsies were obtained during standing surgery for correction of LDA, and from control cows. The concentration of macrominerals in serum, and of total lipids (tLPD) and triglycerides (TG) in liver were determined. Liver was examined histologically, and classified for its severity of fatty liver. Cows with LDA were grouped according to severity of fatty liver. Cows in Groups 1 to 3 recovered, whereas those in Group 4 died within 4 weeks of surgery. Group 1=mild (n=4) or moderate (n=6 cows, n=4 heifers) fatty liver, Group 2 = moderate to severe fatty liver (n=13), Group 3=severe fatty liver (n=15 cows, n=5 heifers), Group 4 = severe fatty liver (n=17 cows, n=4 heifers).

RESULTS: The concentration of macrominerals in serum was affected by the concurrence of fatty liver and LDA; Ca, K and Mg were significantly (p<0.05) lower in animals that died than those that survived. For cows with severe fatty liver, concentrations of tLD and TG were higher in the animals that died compared with those that recovered (p<0.01). Cows with LDA and severe fatty liver that died were earlier in lactation (median days in milk (DIM) 13 days) compared with the other cows with LDA (median DIM 21–26 days) (p<0.05); they were also significantly older (median 6 years old) than cows in the other groups (median 4 or 5 years old) (p–0.05).

CONCLUSIONS AND CLINICAL RELEVANCE: Concentrations of macrominerals in serum were influenced by the concurrence of LDA and fatty liver. Animals with low concentrations of Ca, K and Mg had a guarded prognosis. The concentration of K should always be evaluated in cows with LDA and concurrent fatty liver when providing a prognosis. Most cows with severe fatty liver were detected in the first 4 weeks of lactation, but older animals and those that had more recently calved had a worse prognosis.     

Development of a Chlamydophila psittaci species-specific and genotype-specific real-time PCR

A Chlamydophila psittaci species-specific real-time PCR targeting the rDNA ribosomal spacer was developed as well as a genotype-specific real-time PCR targeting the Cp. psittaci outer membrane protein A (ompA) gene. The SYBR Green-based species-specific real-time PCR detected Cp. psittaci genotypes A to F, and the recently discovered E/B genotype. The genotype-specific real-time PCR could easily distinguish genotypes C, D, F by use of TaqMan probes. Genotypes A, B and E could not be distinguished from each other by simply using TaqMan probes. For this purpose, non-fluorescent competitor oligonucleotides, had to be used next to the TaqMan probes. Genotype E/B could only be detected by use of a minor groove binder (MGB) probe. Both real-time PCR assays allowed reproducible, sensitive (10 rDNA or ompA copies/microL DNA extract) and specific detection of Cp. psittaci DNA. The genotype-specific real-time PCR was compared to ompA sequencing and ompA restriction fragment length polymorphism (RFLP) analysis using five Cp. psittaci field isolates (99, 61/8, 7344/2, 8615/1 and 7778B15) each consisting of two different genotypes. The currently developed real-time PCR assays were used in a case study on a veterinary school and a turkey farm. In the veterinary school, Cp. psittaci genotypes D, E/B and F infection were detected in all five groups of turkeys, and one veterinarian who was taking care of all these turkeys. On the turkey farm, the presence of two Cp. psittaci genotype B infection waves was demonstrated in one randomly selected turkey, the first wave at the age of 6 weeks, and the second at the age of 12 weeks.     

Immunopathology of Chlamydophila abortus infection in sheep and mice

Chlamydophila abortus targets the placenta, causing tissue damage, inflammation and abortion (enzootic abortion of ewes). It is one of the main infectious causes of abortion in ewes, resulting in major economic losses to agricultural industries worldwide. Although ruminants and pigs are the principal hosts, humans are also susceptible to infection. Control of disease requires a host inflammatory response, which is likely to contribute to pathology and abortion. Mouse models have been widely used to provide insight into the role of specific immune cells in controlling infection and disease. The use of such model systems for investigating the mechanisms of abortion, latency, persistence, and immunity to reinfection will result in the identification of novel vaccine control strategies for sheep.     

The detection of Chlamydophila psittaci genotype C infection in dogs

Reports of canine chlamydiosis are infrequent, possibly because the pathogen is rarely considered to be a cause of disease in dogs. This report presents details of Chlamydophila psittaci infection in four bitches with recurrent keratoconjunctivitis, severe respiratory distress and reduced litter size (up to 50% stillborn or non-viable puppies) in a small dog-breeding facility in Germany. Cell culture and immunofluorescence examination of conjunctival, nasal and pharyngeal swabs revealed chlamydial inclusions. PCR and sequencing of ompA amplification products confirmed the presence of Cp. psittaci genotype C. The zoonotic potential of the pathogen was illustrated by evidence of disease in two children that lived on the premises with the infected dogs. There was circumstantial evidence to suggest infection of dogs and humans may have followed the introduction of two canaries and a parrot to the household. The persistent nature of the chlamydial infection suggests that dogs may be reservoirs of Cp. psittaci, but this putative role and whether or not dogs shed the pathogen require further investigation.     

Metabolic signature of spent culture media shows lipid metabolism as a determinant of pregnancy outcomes

In the present study, we investigated the spent culture media of in vitro produced (IVP) bovine embryos which did (group Pregnant) or did not (group Non-pregnant) establish pregnancy after transfer. For that purpose, IVP embryos on D5 were transferred to individual droplets for the last 48 h of culture. Embryos at the blastocyst stage were then transferred to synchronized recipients, while respective culture media drops were collected and evaluated individually. The list of metabolites present in spent culture media was obtained by electrospray ionization mass spectrometry (ESI-MS) and analysed with Metaboanalyst® to characterize the metabolic profile of each group. The spectrometric analysis showed that pathways related to lipid metabolism, particularly fatty acids degradation via beta-oxidation, were more present in the Pregnant group whereas no significant pathway was identified in the group Non-pregnant. By using this method, we were able to identify a metabolic signature in culture media that allows for a better comprehension of preferential metabolic routes taken by the most viable embryos. These findings offer great insights into the biochemistry of embryo development and reveal a potential target for the development of better-quality IVP systems, as well as tools to identify bovine embryos with greater chances to establish and maintain pregnancy.     

Development of a model for the prediction of feed intake by dairy cows: 1. Prediction of feed intake

A study was undertaken to develop a model for the prediction of dry matter intake by lactating Holstein Friesian dairy cows. To estimate the model parameters, a calibration dataset was compiled with the data from 32 feeding experiments conducted at 9 different sites. The database contained weekly information on 1507 lactating Holstein Friesian dairy cows regarding their diet composition and feed analysis, together with their individual voluntary feed intake, milk yield (MY), milk composition, parity, days in lactation and days pregnant.Dry matter intake was predicted from feed and animal characteristics. The feed chemical composition and digestibility can be related to feed degradation, bulk volume, intake rate, palatability and other factors influencing feed intake. Therefore, the data of standard feed analysis were used to estimate the satiety value of numerous commonly used feeds and forages. The satiety value is the measure of the extent to which a feed limits intake. The cows' ability to process the intake-limiting satiety value-units is expressed as the feed intake capacity, which is predicted from parity, days in milk and days of pregnancy which are indicators of the size and physiological state of the cow. This study shows that feed intake can be predicted using a limited number of easy-to-measure inputs that are available on commercial farms, yet reasonably biologically sound. Because the model inputs are not related to animal output (milk yield or body weight), future extension of the intake model with models for the prediction of animal performance is possible.     

Protection in a hamster model of congenital toxoplasmosis

Almost uniform protection against congenital toxoplasmosis initiated by inoculations with cysts and oocysts of the parasite was seen in the hamster model, among strains of different genotypes. Because the RH immunization prior to pregnancy has to be controlled with medication for most of the hamsters to survive, and also some congenital transmission of Toxoplasma was observed during the chronic stage of the infection, the hamster is considered less practical than the rat and the BALB/c mouse models. It is concluded that the hamster model closely resembles protection against congenital infection in nature, where most of the pregnant women and ewes that experienced a toxoplasma infection previously, protect their fetuses against an infection with the parasite during pregnancy.     

Experimental infection of sheep with Brucella abortus

A case of brodifacoum poisoning is described in a six-year-old male Kelpie cross working dog. The clinical features were severe exercise intolerance, haemorrhage from the oral and nasal cavities, dyspnoea and pale mucous membranes. Diagnosis was confirmed by demonstrating an abnormally long whole blood clotting time. The dog was treated successfully by administering 1 litre of whole blood intravenously, intramuscular vitamin K₁ and a three week course of oral vitamin K₃.

Experience at the Massey University Small Animal Clinic and Hospital has indicated that poisoning of dogs with the newer long acting anticoagulant rodenticides is becoming more common.     

Development of a model to predict dietary metabolizable energy from digestible energy in beef cattle

Understanding the utilization of feed energy is essential for precision feeding in beef cattle production. We aimed to assess whether predicting the metabolizable energy (ME) to digestible energy (DE) ratio (MDR), rather than a prediction of ME with DE, is feasible and to develop a model equation to predict MDR in beef cattle. We constructed a literature database based on published data. A meta-analysis was conducted with 306 means from 69 studies containing both dietary DE and ME concentrations measured by calorimetry to test whether exclusion of the y-intercept is adequate in the linear relationship between DE and ME. A random coefficient model with study as the random variable was used to develop equations to predict MDR in growing and finishing beef cattle. Routinely measured or calculated variables in the field (body weight, age, daily gain, intake, and dietary nutrient components) were chosen as explanatory variables. The developed equations were evaluated with other published equations. The no-intercept linear equation was found to represent the relationship between DE and ME more appropriately than the equation with a y-intercept. The y-intercept (−0.025 ± 0.0525) was not different from 0 (P = 0.638), and Akaike and Bayesian information criteria of the no-intercept model were smaller than those with the y-intercept. Within our growing and finishing cattle data, the animal’s physiological stage was not a significant variable affecting MDR after accounting for the study effect (P = 0.213). The mean (±SE) of MDR was 0.849 (±0.0063). The best equation for predicting MDR (n = 106 from 28 studies) was 0.9410 ( ± 0.02160) +0.0042 ( ± 0.00186) × DMI (kg) – 0.0017 ( ± 0.00024) × NDF(% DM) – 0.0022 ( ± 0.00084) × CP(% DM). We also presented a model with a positive coefficient for the ether extract (n = 80 from 22 studies). When using these equations, the observed ME was predicted with high precision (R² = 0.92). The model accuracy was also high, as shown by the high concordance correlation coefficient (>0.95) and small root mean square error of prediction (RMSEP), <5% of the observed mean. Moreover, a significant portion of the RMSEP was due to random bias (> 93%), without mean or slope bias (P > 0.05). We concluded that dietary ME in beef cattle could be accurately estimated from dietary DE and its conversion factor, MDR, predicted by the dry matter intake and concentration of several dietary nutrients, using the 2 equations developed in this study.