Virus and virus-like particles in the faeces of cats with and without diarrhoea

Negative staining electron microscopy was used to identify viruses in 166 normal and 62 diarrhoeal faecal samples from 208 cats admitted to an animal shelter during a 16-month period (March 1984 to June 1985). On the basis of size and shape 7 distinct viral types were detected: 24 nm parvovirus-like particles, 30 nm astrovirus, 30 nm picornavirus-like particles, reovirus, rotavirus, coronavirus and a 75 nm "togavirus-like" particle. The incidence of these particles in the 208 cats was 11%, 7%, 6%, 0.4%, 5%, 1% and 1% respectively. Virus isolation studies using 40 of the faecal samples succeeded in isolating reovirus 1 in 2 cases. Immune electron microscope studies demonstrated the presence of antibody in a human serum to cat astrovirus, but failed to clarify the identity of the parvovirus-like particles and picornavirus-like particles, other than showing that some of the parvovirus-like particles were not related to feline panleukopenia virus. It was found that parvovirus-like particles, astrovirus, picornavirus-like particles, reovirus and rotavirus could be excreted by cats with normal faeces as well as cats with diarrhoeal faeces. Parvovirus-like particles, astrovirus, picornavirus-like particles and rotavirus could be excreted in high concentration in normal faeces. There was no simple relationship between age and diarrhoea in the population of cats studied. Age was not a critical factor in the excretion of parvovirus-like particles, astrovirus, picornavirus-like particles and rotavirus. The incidence of diarrhoea was not clearly associated with the seasons.     

H9N2亚型流感病毒光动力失活的超微结构

使用H9N2亚型流感病毒作为系统模型,用不同浓度(2,4 μmol/L)的光敏剂经激光照射(12 J/cm2,20 min),使病毒颗粒失活后,使用透射电子显微镜(TEM)观察病毒粒子形态,并对病毒的感染性进行测定.结果显示,低浓度光敏剂处理组的病毒粒子膜结构虽然保持完整性,但表面糖蛋白缺失,同时丧失了对MDCK细胞的...     

双环缝喷射共沉积SiC颗粒的捕获与分布研究

采用坩埚移动式喷射共沉积装置及其双环缝复合雾化器制备了SiC颗粒增强铝基复合材料坯件,研究了过程中增强颗粒的捕获机制及特点.实验结果表明,双环缝复合雾化器所引入的SiC颗粒捕获率较高,分布均匀;增强颗粒主要在雾化初时阶段被雾化液滴所捕获,而沉积坯表面因基本呈固相且温度较低,对SiC颗粒的直接捕获效果不明显;沉积坯快冷凝固界面前沿捕获对SiC颗粒的分布影响不大,SiC颗粒在沉积坯中的最终分布主要取决于由雾化液滴对增强颗粒的捕获,特别决定于SiC颗粒在单个雾化颗粒内部及空间雾化颗粒群中的分布.     

The ultrastructure of bull sperm membranes prepared by freeze etching

Intramembraneous particles represent protein components of the membrane. It is assumed that their number and distribution are in correlation with the level of the metabolic activity of membranes. In the cytoplasmic membrane in the postacrosomal region (PF) near the posterior ring the particles are arranged in form of palisade rows. In the remaining membranes of the head, irregularly distributed particles were observed. Their number at individual places varied. Their size was not equal either. The areas without particles were also found out. The particles in the cytoplasmic membrane of the flagellum (PF) formed clusters and they had circumferential orientation in the direction of mitochondria. At the place of the annulus the number of particles increased. The distribution of particles was irregular in the cytoplasmic membrane of the main section.     

Feline panleucopenia--in vivo infectivity studies

Feline panleucopenia virus was separated into "full" and "empty" particles by banding in caesium chloride ultracentrifugation. Field cats free of serum neutralising antibodies were separately infected with "full", "empty" and "mixed" particles of the virus. No clinical disease was produced. However, cats infected with "full" particles developed antibody more rapidly than cats infected with the other particles.     

Detection and Localization of Aleutian Disease Virus and its Antigens in vivo by Immunoferritin Technique

Tissues from mink infected with aleutian disease virus were examined by the electron microscope for the presence of virus particles. Virus-like particles, measuring 22 nm in diameter, were observed in macrophages of spleen, mesenteric lymph node and in Kupffer cells in liver of mink ten to 13 days after infection. The virus-like particles were usually present in vacuoles inside the cytoplasm of macrophages and Kupffer cells and, occasionally, similar particles were observed inside the nucleus. Cells from uninfected mink did not contain such patricles. To correlate the existence of these virus-like particles with the presence of aleutian disease virus antigen in infected cells, tissues were processed for immunoferritin technique. It was found that aleutian disease virus antigen was present in vacuoles inside the cytoplasm of cells from the infected spleen, lymph node and liver, and that the location was similar to that of the 22 nm virus-like particles. In addition, some viral antigen was also detected as cytoplasmic granular material. The nuclei of some cells also contained aleutian disease virus antigen. The pattern of aleutian disease virus antigen was similar to the distribution of virus-like particles in cells of infected tissue. It is suggested that virus replication occurs inside the nucleus with subsequent accumulation of virus in the vacuoles of the cytoplasm.     

Inhibition and enhancement of avian adenovirus plaque production by heavy and light avian adenovirus-associated viral particles.

The effect of heavy and light avian adenovirus-associated viral (A-AV) particles on the replication of several adenovirus serotypes was studied in chicken embryo kidney cells. There was a significant decrease (P less than 0.05) in the number and size of adenovirus-induced plaques at A-AV multiplicities of infection greater than 40. Enhancement of plaque production was observed when A-AV multiplicities of infection were 1 to 40. There was a significant increase in the number and size of infective centers. Analysis of cellular yields indicated an increase in the number of adenoviruses produced per cell. Heavy A-AV particles of buoyant density 1.42 g/cm3 in CsCl were found to enhance plaque production more than light particles (1.38 g/cm3). Conversely, light particles showed greater inhibition of plaque production. Adenovirus serotypes varied in their response to enhancement or inhibition by A-AV particles of different density.     

Digestive processes of dairy cows fed silages harvested at four stages of grass maturity

The objective of this experiment was to quantify ruminal digestive processes that could help to identify factors limiting DMI when silages differing in grass maturity were fed to dairy cows. Four silages were harvested at 1-wk intervals from a primary growth of a timothy-meadow fescue sward, resulting in feeds with digestible OM content in DM (D-value) of 739, 730, 707, and 639 g/kg in the order of succeeding harvest date. Four ruminally cannulated dairy cows were given ad libitum access to these silages supplemented with 7 kg concentrate per day in a 4 x 4 Latin square design. Rumen function was clearly affected by decreasing digestibility of silage fed. Passage rate of digestible NDF (DNDF) and indigestible NDF (INDF) increased, but it could not prevent the accumulation of DM, NDF, DNDF, and INDF into the rumen when silages of progressing grass maturity were fed. The greatest proportional increases in rumen pool were found in INDF and in medium particles (separated by wet sieving and measuring 315 to 2,500 microm). The passage of medium INDF particles decreased (P < 0.01) linearly (from 0.0365/h to 0.0281/h) with increasing maturity of grass ensiled, and it was slower than passage of small (80 to 315 microm) particles (on average 0.0524/h). Particle size reduction of large INDF particles to medium INDF particles was slower (P < 0.001) in the early cut silages (0.0216/h to 0.0484/h) but reduction of medium INDF particles to small INDF particles was faster (P < 0.001) in early cut silages (0.0436 to 0.0305). Passage of medium size particles and(or) rate of medium particle breakdown to small particles were potential intake-constraining properties of low digestibility forages, whereas large particle reduction to medium particles seemed not to be limiting. The increased feed intake of the early-cut silages was accompanied by decreased rumen fill, suggesting that rumen fill was not at least solely responsible for feed intake control.     

Physical, chemical, and serological characterization of avian rotaviruses

Physical, chemical, and serological characterization of rotavirus isolates from turkeys was done. Cesium chloride (CsCl)-gradient isopycnic centrifugation of infected cell cultures revealed the presence of rotavirus particles of three different densities. They were double-shelled, single-shelled, and core particles. The double-shelled particles had a buoyant density (in CsCl) of 1.34 g/cml3, and that of single-shelled particles in CsCl was 1.36 g/cm3. The buoyant density of core particles in CsCl was greater than 1.40 g/cm3. These rotavirus isolates were not inactivated by chloroform and were relatively stable at pH 3.0. Their replication was not affected by 5-bromo-2'-deoxyuridine. Avian rotaviruses were not completely inactivated by heat treatment of 56 C for 8 hr. All six avian rotavirus isolates examined were antigenically related to each other. However, there was no antigenic relationship between mammalian rotaviruses and the avian rotavirus isolates examined.     

Diagnosis of avian viral diseass by electron microscopy.

Clinical material from avian species was examined directly by electron microscopy for the presence of viruses. Mycoplasma-like and coronavirus-like particles were found in chicken feces. These particles did not appear to be associated with disease and were not propagated in the laboratory. Infectious bursal disease virus was readily detected in impression smears of bursas from experimentally infected birds. Poxviruses were demonstrated in smears made from canarypox lesions. Difficulty in distinguishing intact particles of Newcastle disease virus from mycoplasmas and orthomyxoviruses was resolved by treating viral preparations with deoxycholate. After treatment, Newcastle disease virus was lysed, rendering the nucleocapsid visible, whereas influenza virus was mainly unaffected. Viral particles that were recognized only with difficulty by direct elecron microscopic examination were more easily identified using immunoelectron microscopy.     

A highly virulent togavirus-like agent associated with the fulminating disease of guinea fowl.

During a 1986 natural lethal outbreak of fulminating disease in guinea poult flocks in southwestern France, enveloped virus particles were consistently observed in the gut contents of infected birds. For the present study, a protocol was developed for the purification of these particles. Sucrose-banded virus obtained from birds infected experimentally with virus from the outbreak was found to have a buoyant density of 1.18 g/ml. The purified virus showed hemagglutinating activity, was shown by electron microscopy to have a togavirus-like morphology, and also was shown to be transmissible and pathogenic through oral ingestion. In addition, other enveloped particles have been occasionally detected in gut contents of both infected and uninfected birds; the improbability of the viral nature of these interfering particles is discussed.     

Large particle breakdown by cattle eating ryegrass and alfalfa

The proportion of large particles (LP) broken down to small, insoluble particles by primary mastication (eating), rumination, digestion and detrition (rubbing) was determined for separated leaf and stem fractions of perennial ryegrass (Lolium perenne) and alfalfa (Medicago sativa) fed to cattle cannulated at the esophagus. Large particles were defined as those particles retained during wet sieving on a screen with an aperture of 1.18 mm. Reduction in weight of particles caused by solubilizing or digestion was not considered to be particle breakdown per se, and particles were corrected for this loss in weight. The proportion of LP in the forage broken down by primary mastication was 25 +/- 1.9% (means +/- SE). Breakdown of LP by rumination was calculated from the weight of total particles regurgitated and the proportion of LP in the regurgitated and swallowed remasticated material. The weight of LP regurgitated was corrected for the dry matter lost by digestion using lignin ratio in the LP entering the rumen and of the regurgitated digesta. Rumination accounted for 50 +/- 1.5% of LP breakdown. Fecal loss accounted for 8 +/- .8% of the LP in forage. Breakdown of LP by digestion and detrition was calculated as 17 +/- 1.3% from the difference between the LP eaten and those broken down by primary mastication, rumination and passing out in the feces. The significance of these results for predicting voluntary intake from laboratory analysis is considered.     

Dietary concentrate level affects the feed sorting behaviour of lambs

The objective of this study was to evaluate the effect of forage concentration on sorting, nutrient intake and feeding behaviour of growing lambs. Twelve weaned lambs were exposed, in a crossover design with 7‐day periods, to each of two treatment diets: (i) lower‐concentrate diet (LC; 40.0% concentrate) and (ii) a higher‐concentrate diet (HC; 60.0% concentrate). Alfalfa hay was used as forage source. Sorting was determined by subjecting fresh feed and ort samples to particle separation and expressing the actual intake of each particle fraction as a percentage of the predicted intake of that fraction. Lambs sorted against long particles (>19 mm) on both treatments. On the LC diet, lambs sorted for medium particles, whereas animals fed the HC diet did not sort for or against medium particles. Lambs sorted for fine particles (<1.18 mm) on both treatments (p < .05). The extent of sorting for the fine particles was greater on the LC diet compared with the HC diet (p < .05). Dry matter intake was increased by increasing the concentrate content of the diet. Intake per visit and eating rate increased, and total chewing time was decreased in lambs fed HC diet. In conclusion, lambs sorted most against the longest particles and for the fine particles. Furthermore, feed sorting behaviour is affected by the forage level, and lambs sorted more for the fine particles in the LC diet.     

Estimation of 140S particles in foot-and-mouth disease virus (FMDV) vaccine by using the computer analyzing system

The quantity of 140S particles in inactivated foot-and-mouth disease virus (FMDV) vaccine samples produced in Foot-and-Mouth Disease Vaccine Production Center (FMD Vaccine Production Center) in Thailand was estimated by the sucrose gradient ultracentrifugation and optical density analysis by using the computer applying system. The soft ware; Chromato Data System (CDS) (Nihon Chromato Works Co., Ltd. Japan) which is prepared for the analysis of chromatography, was applied for the estimation of 140S particles in FMDV vaccine. The quantity of 140S particles in each vaccine sample measured by CDS was mostly ranged from 2-4 micrograms/ml and this quantity was consistent with the results of the other reports. This method is considered to be the available method for estimation of 140S particles in FMDV vaccine as routine assay.     

Electron microscopic findings of cells with inclusion bodies in experimental hemorrhagic enteritis of turkeys.

The spleen, liver, bone marrow and intestines of two turkeys in which hemorrhagic enteritis of turkeys was experimentally reproduced were examined electron-microscopically. Intranuclear inclusion bodies as described in a previous report were found in all the tissues examined. These occupied most of the area in affected nuclei and were composed of viral particles with morphological characteristics of an adenovirus. The cells with the inclusions were divided into two types of cells, immature and reticular cells. There was some variety in the stage of differentiation of the former cells. As the viral particles developed the cells degenerated and disintegrated. A few particles had been released into the cytoplasm of the degenerated cells but no particles were present in intercellular spaces.     

含组氨酸蛋白标签的蓝舌病假病毒物质构建及定量分析

基于蓝舌病（bluetongue,BT）的危害及RNA阳性质控品研制的重要性,试验将pTrcHis-MS2质粒借助点突变技术在噬菌体外壳蛋白15和16氨基酸之间插入组氨酸（His）蛋白标签,构建了pTrcMS载体。将pMD19-T-BTV质粒与pTrcMS质粒分别进行KpnⅠ和Hind Ⅲ双酶切,然后连接构建pTrcMS-BTV重组质粒。将pTrcMS-BTV重组菌进行原核表达,产物借助偶联His蛋白标签的磁珠捕获技术获得纯化的蓝舌病假病毒颗粒,进行特性鉴定并定量。结果显示,研制的pTrcMS-BTV物质经PCR方法评价纯度高,无基因DNA污染;透射电镜观察形态为不规则的直径约为26 nm的多边形;RT-PCR方法检测稳定性表明该物质耐RNase A,易保存;应用荧光RT-PCR检测表明该物质溶液最低检测限可达到2.5×10²拷贝/mL。蓝舌病假病毒物质将为蓝舌病分子生物学检测提供阳性质控物质。     

Comparative selective retention of particle size classes in the gastrointestinal tract of ponies and goats

There is a discrepancy in the literature on potential digesta separation mechanisms in horses, with both a selective retention of fine and of large particles postulated in different publications. To assess the net effect of such mechanisms, we fed ponies on a hay‐only diet a pulse dose of whole (unchopped) marked hay together with a solute marker, collected faeces on a regular basis, measured marker concentrations in whole faeces and in their large (2.0–16 mm), medium (0.5–1.0 mm) and small (0.063–0.25 mm) particle fraction, and calculated the corresponding mean retention times (MRTs). For comparison, the same experiment was performed in goats. In goats, as expected, MRT_solute (35 hr) was significantly shorter than MRT_particle (51 hr); only a very small fraction of particle marker was excreted as large particles (2%); and the MRT of these large particles was significantly shorter than that of small particles (with a relevant difference of 8.6 hr), indicating that those few large particles that escape the rumen do so mostly soon after ingestion. In ponies, MRT_solute (24 hr) did not differ from MRT_particle (24 hr); a higher fraction of particle marker was excreted as large particles (5%); and the MRT of these large particles was longer than that of small particles (but with a non‐relevant difference of less than 1 hr). These results indicate that no relevant net separation of digesta phases occurs in horses and that selective particle retention mechanisms in the large intestine are unlikely to represent important characteristics of the horse's digestive physiology.     

Changes in ruminal and fecal particle weight distribution of steers fed coastal bermudagrass hay at four levels

Samples of digesta from the ruminal upper strata (RUS) and feces (F) were taken from four ruminally cannulated steers fed Coastal bermudagrass hay (78% NDF) in the long form to evaluate the effects of feeding level and time postfeeding on particle breakdown. The experimental design was a 4 x 4 Latin square with 18-d periods. Treatments based on previous intakes were set at 50, 70, 90 and 110% (3.1, 4.4, 5.5 and 6.7 kg/d, respectively) of feed consumed per animal and fed at 12-h intervals. Samples were taken at 2, 6 and 12h postfeeding and wet-sieved. Dry matter weight distribution of total recovered particles was used to partition RUS and F digesta among percentages of large (greater than 4.0 mm), medium (greater than 4.0 and less than or equal to 1.0 mm), small (less than 1.0 and greater than or eual to .125 mm) and fine (less than .125 and greater than or equal to .0027 mm) particles. With increasing feeding level, the percentage of medium RUS particles increased linearly (P less than .02), whereas the percentage of fine RUS particles decreased linearly (P less than .01). Increased time postfeeding resulted in a linear decrease in the percentage of large RUS particles (P less than .01), a linear increase in the percentage of small RUS particles (P less than .01) and in a quadratic increase in the percentage of fine RUS particles (P less than .01). Percentage of medium RUS particles remained unchanged. Increasing feeding level resulted in linear increases in mean RUS (P less than .01) and F (P less than .02) particle sizes. Percentages of RUS and F material passing through a 1.0-mm sieve averaged 52.8 and 88.8%, respectively. Animal-to-animal variation in proportions of RUS and mixed reticuloruminal particles was not entirely removed by rumination and was still reflected in the percentages of F particles. Factors such as particle entrapment in the fiber mat, reticular sedimentation, changes in specific gravity, swelling and hydration capacity, reticuloruminal motility and amount of digesta exiting per contraction appear to be more important than particle size reduction in the regulation of the passage of digesta from the reticulorumen.     

伪狂犬病病毒吉林分离株感染BHK-21细胞的超微结构变化

以猪伪狂犬病病毒(PRV)吉林分离株PRV-JL感染体外培养的BHK-21细胞为模型,通过透射电镜对PRV的形态发生学和宿主细胞超微结构的动态变化规律进行研究。结果显示,PRV能导致BHK-21细胞圆缩,并发生细胞融合,形成合胞体;电镜观察到的病毒粒子呈球形或椭圆形,成熟的病毒粒子直径大小为140~210 nm,未成熟病毒粒子直径为90~150 nm,多呈中空状,部分呈致密核芯。病毒吸附于细胞后以膜融合的方式进入细胞,在胞核内复制,装配好的病毒粒子以出芽的方式离开细胞核,获得最初的囊膜,进入胞浆;在胞浆内的病毒粒子又利用高尔基体的膜结构合成第2层囊膜,形成完整的病毒粒子;最后包裹有完整病毒粒子的高尔基囊泡与细胞膜发生融合,将病毒粒子释放到细胞外。感染细胞超微结构变化主要表现为:细胞胞浆空泡增多,内质网扩张,线粒体增生、嵴肿胀、脱落,最后空泡化,整个细胞裂解、破碎。     

Viruses and virus-like particles in the faeces of dogs with and without diarrhoea

Negative staining electron microscopy was used to identify viruses in 157 normal and 29 diarrhoeal faecal samples collected from 156 dogs admitted to an animal shelter during an 8 month period (March to October) in 1982. Seven distinct viral types were detected: 21-26 nm parvovirus-like particles, 28-31 nm astrovirus-like particles, a previously undescribed 34-35 nm "round" virus particle, coronavirus, coronavirus-like particles ( CVLP ), rotavirus and papova-like virus. Parvovirus-like particles alone were detected in 14 diarrhoeal and 50 normal faeces, astrovirus-like particles in 3 normal faeces, "round" viruses in 4 normal faeces, coronavirus in 2 diarrhoeal and 5 normal faeces, CVLP in one diarrhoeal and one normal faeces, rotavirus in 2 normal faeces, papova-like virus in one normal faeces, both parvovirus-like particles and coronavirus in 2 diarrhoeal and 2 normal faeces, parvovirus-like particles and rotavirus in one normal faeces and parvovirus-like and papova-like virus in one normal faeces. The significance of these findings in canine and human disease is discussed.